vim: runtime/doc/vim9class.txt annotate

annotate runtime/doc/vim9class.txt @ 33385:b5ad84fdc702 v9.0.1951

patch 9.0.1951: Vim9: hard to debug vim9_class errors from CI Commit: https://github.com/vim/vim/commit/b90e3bc491c02bd6e4db1a1c1849ce3d21811c43 Author: Yegappan Lakshmanan <yegappan@yahoo.com> Date: Thu Sep 28 23:06:48 2023 +0200 patch 9.0.1951: Vim9: hard to debug vim9_class errors from CI Problem: Vim9: hard to debug vim9_class errors from CI Solution: Include the line number in assert_xxx() calls. Include the entire error message in the tests. Fix the indentation in the test file. Add tags for new error codes. closes: #13206 Signed-off-by: Christian Brabandt <cb@256bit.org> Co-authored-by: Yegappan Lakshmanan <yegappan@yahoo.com>

author	Christian Brabandt <cb@256bit.org>
date	Thu, 28 Sep 2023 23:30:03 +0200
parents	5c12ca4dcd45
children	bb99820510ef

rev	line source
33286 0c3553cfe22e patch 9.0.1909: Vim9: problem calling class method from other class Christian Brabandt <cb@256bit.org> parents: 33217 diff changeset	1 vim9class.txt For Vim version 9.0. Last change: 2023 Sep 18
31335 5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	2
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	3
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	4 VIM REFERENCE MANUAL by Bram Moolenaar
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	5
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	6
31885 cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	7 NOTE - This is not finished yet, anything can still change! - NOTE
31335 5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	8
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	9
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	10 Vim9 classes, objects, interfaces, types and enums.
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	11
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	12 1. Overview \|Vim9-class-overview\|
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	13 2. A simple class \|Vim9-simple-class\|
33286 0c3553cfe22e patch 9.0.1909: Vim9: problem calling class method from other class Christian Brabandt <cb@256bit.org> parents: 33217 diff changeset	14 3. Class variables and methods \|Vim9-class-member\|
31885 cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	15 4. Using an abstract class \|Vim9-abstract-class\|
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	16 5. Using an interface \|Vim9-using-interface\|
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	17 6. More class details \|Vim9-class\|
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	18 7. Type definition \|Vim9-type\|
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	19 8. Enum \|Vim9-enum\|
31335 5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	20
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	21 9. Rationale
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	22 10. To be done later
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	23
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	24 ==============================================================================
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	25
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	26 1. Overview Vim9-class-overview
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	27
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	28 The fancy term is "object-oriented programming". You can find lots of study
31885 cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	29 material on this subject. Here we document what \|Vim9\| script provides,
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	30 assuming you know the basics already. Added are helpful hints about how to
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	31 use this functionality effectively.
31335 5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	32
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	33 The basic item is an object:
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	34 - An object stores state. It contains one or more variables that can each
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	35 have a value.
31885 cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	36 - An object provides functions that use and manipulate its state. These
31335 5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	37 functions are invoked "on the object", which is what sets it apart from the
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	38 traditional separation of data and code that manipulates the data.
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	39 - An object has a well defined interface, with typed member variables and
33351 a3bbd065fb87 runtime(doc): Vim9: Consistenly use class/object variable and class/object method in help (#13149) Christian Brabandt <cb@256bit.org> parents: 33286 diff changeset	40 methods.
31885 cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	41 - Objects are created from a class and all objects have the same interface.
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	42 This does not change at runtime, it is not dynamic.
31335 5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	43
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	44 An object can only be created by a class. A class provides:
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	45 - A new() method, the constructor, which returns an object for the class.
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	46 This method is invoked on the class name: MyClass.new().
31885 cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	47 - State shared by all objects of the class: class variables (class members).
31335 5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	48 - A hierarchy of classes, with super-classes and sub-classes, inheritance.
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	49
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	50 An interface is used to specify properties of an object:
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	51 - An object can declare several interfaces that it implements.
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	52 - Different objects implementing the same interface can be used the same way.
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	53
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	54 The class hierarchy allows for single inheritance. Otherwise interfaces are
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	55 to be used where needed.
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	56
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	57
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	58 Class modeling ~
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	59
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	60 You can model classes any way you like. Keep in mind what you are building,
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	61 don't try to model the real world. This can be confusing, especially because
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	62 teachers use real-world objects to explain class relations and you might think
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	63 your model should therefore reflect the real world. It doesn't! The model
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	64 should match your purpose.
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	65
31885 cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	66 Keep in mind that composition (an object contains other objects) is often
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	67 better than inheritance (an object extends another object). Don't waste time
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	68 trying to find the optimal class model. Or waste time discussing whether a
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	69 square is a rectangle or that a rectangle is a square. It doesn't matter.
31335 5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	70
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	71
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	72 ==============================================================================
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	73
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	74 2. A simple class Vim9-simple-class
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	75
31885 cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	76 Let's start with a simple example: a class that stores a text position (see
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	77 below for how to do this more efficiently): >
31335 5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	78
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	79 class TextPosition
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	80 this.lnum: number
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	81 this.col: number
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	82
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	83 def new(lnum: number, col: number)
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	84 this.lnum = lnum
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	85 this.col = col
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	86 enddef
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	87
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	88 def SetLnum(lnum: number)
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	89 this.lnum = lnum
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	90 enddef
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	91
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	92 def SetCol(col: number)
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	93 this.col = col
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	94 enddef
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	95
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	96 def SetPosition(lnum: number, col: number)
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	97 this.lnum = lnum
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	98 this.col = col
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	99 enddef
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	100 endclass
31430 e5e95e8c78a7 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31396 diff changeset	101 < object Object
31335 5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	102 You can create an object from this class with the new() method: >
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	103
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	104 var pos = TextPosition.new(1, 1)
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	105
33351 a3bbd065fb87 runtime(doc): Vim9: Consistenly use class/object variable and class/object method in help (#13149) Christian Brabandt <cb@256bit.org> parents: 33286 diff changeset	106 The object variables "lnum" and "col" can be accessed directly: >
31335 5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	107
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	108 echo $'The text position is ({pos.lnum}, {pos.col})'
31430 e5e95e8c78a7 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31396 diff changeset	109 < E1317 E1327
31335 5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	110 If you have been using other object-oriented languages you will notice that
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	111 in Vim the object members are consistently referred to with the "this."
31885 cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	112 prefix. This is different from languages like Java and TypeScript. The
31335 5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	113 naming convention makes the object members easy to spot. Also, when a
33351 a3bbd065fb87 runtime(doc): Vim9: Consistenly use class/object variable and class/object method in help (#13149) Christian Brabandt <cb@256bit.org> parents: 33286 diff changeset	114 variable does not have the "this." prefix you know it is not an object
a3bbd065fb87 runtime(doc): Vim9: Consistenly use class/object variable and class/object method in help (#13149) Christian Brabandt <cb@256bit.org> parents: 33286 diff changeset	115 variable.
31335 5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	116
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	117
33351 a3bbd065fb87 runtime(doc): Vim9: Consistenly use class/object variable and class/object method in help (#13149) Christian Brabandt <cb@256bit.org> parents: 33286 diff changeset	118 Object variable write access ~
31335 5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	119
33351 a3bbd065fb87 runtime(doc): Vim9: Consistenly use class/object variable and class/object method in help (#13149) Christian Brabandt <cb@256bit.org> parents: 33286 diff changeset	120 Now try to change an object variable directly: >
31335 5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	121
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	122 pos.lnum = 9
31885 cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	123 < E1335
33351 a3bbd065fb87 runtime(doc): Vim9: Consistenly use class/object variable and class/object method in help (#13149) Christian Brabandt <cb@256bit.org> parents: 33286 diff changeset	124 This will give you an error! That is because by default object variables can
a3bbd065fb87 runtime(doc): Vim9: Consistenly use class/object variable and class/object method in help (#13149) Christian Brabandt <cb@256bit.org> parents: 33286 diff changeset	125 be read but not set. That's why the TextPosition class provides a method for
a3bbd065fb87 runtime(doc): Vim9: Consistenly use class/object variable and class/object method in help (#13149) Christian Brabandt <cb@256bit.org> parents: 33286 diff changeset	126 it: >
31335 5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	127
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	128 pos.SetLnum(9)
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	129
33351 a3bbd065fb87 runtime(doc): Vim9: Consistenly use class/object variable and class/object method in help (#13149) Christian Brabandt <cb@256bit.org> parents: 33286 diff changeset	130 Allowing to read but not set an object variable is the most common and safest
31335 5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	131 way. Most often there is no problem using a value, while setting a value may
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	132 have side effects that need to be taken care of. In this case, the SetLnum()
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	133 method could check if the line number is valid and either give an error or use
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	134 the closest valid value.
31885 cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	135 :public E1331
33351 a3bbd065fb87 runtime(doc): Vim9: Consistenly use class/object variable and class/object method in help (#13149) Christian Brabandt <cb@256bit.org> parents: 33286 diff changeset	136 If you don't care about side effects and want to allow the object variable to
a3bbd065fb87 runtime(doc): Vim9: Consistenly use class/object variable and class/object method in help (#13149) Christian Brabandt <cb@256bit.org> parents: 33286 diff changeset	137 be changed at any time, you can make it public: >
31335 5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	138
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	139 public this.lnum: number
31885 cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	140 public this.col: number
31335 5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	141
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	142 Now you don't need the SetLnum(), SetCol() and SetPosition() methods, setting
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	143 "pos.lnum" directly above will no longer give an error.
33286 0c3553cfe22e patch 9.0.1909: Vim9: problem calling class method from other class Christian Brabandt <cb@256bit.org> parents: 33217 diff changeset	144 E1326
33351 a3bbd065fb87 runtime(doc): Vim9: Consistenly use class/object variable and class/object method in help (#13149) Christian Brabandt <cb@256bit.org> parents: 33286 diff changeset	145 If you try to set an object variable that doesn't exist you get an error: >
31579 7d68a90cbf5c Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31441 diff changeset	146 pos.other = 9
33286 0c3553cfe22e patch 9.0.1909: Vim9: problem calling class method from other class Christian Brabandt <cb@256bit.org> parents: 33217 diff changeset	147 < E1326: Member not found on object "TextPosition": other ~
31335 5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	148
33286 0c3553cfe22e patch 9.0.1909: Vim9: problem calling class method from other class Christian Brabandt <cb@256bit.org> parents: 33217 diff changeset	149 E1376
33351 a3bbd065fb87 runtime(doc): Vim9: Consistenly use class/object variable and class/object method in help (#13149) Christian Brabandt <cb@256bit.org> parents: 33286 diff changeset	150 A object variable cannot be accessed using the class name.
31335 5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	151
33351 a3bbd065fb87 runtime(doc): Vim9: Consistenly use class/object variable and class/object method in help (#13149) Christian Brabandt <cb@256bit.org> parents: 33286 diff changeset	152 Private variables ~
33383 5c12ca4dcd45 patch 9.0.1950: Vim9: error codes spread out Christian Brabandt <cb@256bit.org> parents: 33379 diff changeset	153 private-variable E1332 E1333
33351 a3bbd065fb87 runtime(doc): Vim9: Consistenly use class/object variable and class/object method in help (#13149) Christian Brabandt <cb@256bit.org> parents: 33286 diff changeset	154 On the other hand, if you do not want the object variables to be read directly,
31335 5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	155 you can make them private. This is done by prefixing an underscore to the
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	156 name: >
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	157
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	158 this._lnum: number
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	159 this._col number
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	160
33351 a3bbd065fb87 runtime(doc): Vim9: Consistenly use class/object variable and class/object method in help (#13149) Christian Brabandt <cb@256bit.org> parents: 33286 diff changeset	161 Now you need to provide methods to get the value of the private variables.
31885 cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	162 These are commonly called getters. We recommend using a name that starts with
31335 5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	163 "Get": >
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	164
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	165 def GetLnum(): number
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	166 return this._lnum
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	167 enddef
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	168
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	169 def GetCol() number
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	170 return this._col
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	171 enddef
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	172
33351 a3bbd065fb87 runtime(doc): Vim9: Consistenly use class/object variable and class/object method in help (#13149) Christian Brabandt <cb@256bit.org> parents: 33286 diff changeset	173 This example isn't very useful, the variables might as well have been public.
31335 5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	174 It does become useful if you check the value. For example, restrict the line
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	175 number to the total number of lines: >
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	176
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	177 def GetLnum(): number
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	178 if this._lnum > this._lineCount
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	179 return this._lineCount
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	180 endif
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	181 return this._lnum
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	182 enddef
33286 0c3553cfe22e patch 9.0.1909: Vim9: problem calling class method from other class Christian Brabandt <cb@256bit.org> parents: 33217 diff changeset	183 <
33025 1d18c7fe609f patch 9.0.1804: Vim9: no support for private object methods Christian Brabandt <cb@256bit.org> parents: 32960 diff changeset	184 Private methods ~
33383 5c12ca4dcd45 patch 9.0.1950: Vim9: error codes spread out Christian Brabandt <cb@256bit.org> parents: 33379 diff changeset	185 private-method E1366
33025 1d18c7fe609f patch 9.0.1804: Vim9: no support for private object methods Christian Brabandt <cb@256bit.org> parents: 32960 diff changeset	186 If you want object methods to be accessible only from other methods of the
1d18c7fe609f patch 9.0.1804: Vim9: no support for private object methods Christian Brabandt <cb@256bit.org> parents: 32960 diff changeset	187 same class and not used from outside the class, then you can make them
1d18c7fe609f patch 9.0.1804: Vim9: no support for private object methods Christian Brabandt <cb@256bit.org> parents: 32960 diff changeset	188 private. This is done by prefixing the method name with an underscore: >
1d18c7fe609f patch 9.0.1804: Vim9: no support for private object methods Christian Brabandt <cb@256bit.org> parents: 32960 diff changeset	189
1d18c7fe609f patch 9.0.1804: Vim9: no support for private object methods Christian Brabandt <cb@256bit.org> parents: 32960 diff changeset	190 class SomeClass
1d18c7fe609f patch 9.0.1804: Vim9: no support for private object methods Christian Brabandt <cb@256bit.org> parents: 32960 diff changeset	191 def _Foo(): number
1d18c7fe609f patch 9.0.1804: Vim9: no support for private object methods Christian Brabandt <cb@256bit.org> parents: 32960 diff changeset	192 return 10
1d18c7fe609f patch 9.0.1804: Vim9: no support for private object methods Christian Brabandt <cb@256bit.org> parents: 32960 diff changeset	193 enddef
1d18c7fe609f patch 9.0.1804: Vim9: no support for private object methods Christian Brabandt <cb@256bit.org> parents: 32960 diff changeset	194 def Bar(): number
1d18c7fe609f patch 9.0.1804: Vim9: no support for private object methods Christian Brabandt <cb@256bit.org> parents: 32960 diff changeset	195 return this._Foo()
1d18c7fe609f patch 9.0.1804: Vim9: no support for private object methods Christian Brabandt <cb@256bit.org> parents: 32960 diff changeset	196 enddef
1d18c7fe609f patch 9.0.1804: Vim9: no support for private object methods Christian Brabandt <cb@256bit.org> parents: 32960 diff changeset	197 endclass
1d18c7fe609f patch 9.0.1804: Vim9: no support for private object methods Christian Brabandt <cb@256bit.org> parents: 32960 diff changeset	198 <
1d18c7fe609f patch 9.0.1804: Vim9: no support for private object methods Christian Brabandt <cb@256bit.org> parents: 32960 diff changeset	199 Accessing a private method outside the class will result in an error (using
1d18c7fe609f patch 9.0.1804: Vim9: no support for private object methods Christian Brabandt <cb@256bit.org> parents: 32960 diff changeset	200 the above class): >
1d18c7fe609f patch 9.0.1804: Vim9: no support for private object methods Christian Brabandt <cb@256bit.org> parents: 32960 diff changeset	201
1d18c7fe609f patch 9.0.1804: Vim9: no support for private object methods Christian Brabandt <cb@256bit.org> parents: 32960 diff changeset	202 var a = SomeClass.new()
1d18c7fe609f patch 9.0.1804: Vim9: no support for private object methods Christian Brabandt <cb@256bit.org> parents: 32960 diff changeset	203 a._Foo()
1d18c7fe609f patch 9.0.1804: Vim9: no support for private object methods Christian Brabandt <cb@256bit.org> parents: 32960 diff changeset	204 <
31335 5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	205 Simplifying the new() method ~
33383 5c12ca4dcd45 patch 9.0.1950: Vim9: error codes spread out Christian Brabandt <cb@256bit.org> parents: 33379 diff changeset	206 new() constructor
33351 a3bbd065fb87 runtime(doc): Vim9: Consistenly use class/object variable and class/object method in help (#13149) Christian Brabandt <cb@256bit.org> parents: 33286 diff changeset	207 Many constructors take values for the object variables. Thus you very often
a3bbd065fb87 runtime(doc): Vim9: Consistenly use class/object variable and class/object method in help (#13149) Christian Brabandt <cb@256bit.org> parents: 33286 diff changeset	208 see this pattern: >
31335 5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	209
31885 cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	210 class SomeClass
31335 5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	211 this.lnum: number
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	212 this.col: number
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	213
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	214 def new(lnum: number, col: number)
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	215 this.lnum = lnum
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	216 this.col = col
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	217 enddef
31885 cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	218 endclass
33379 7c9124711f99 patch 9.0.1948: Vim9: object variable "this." should only be used in constructor Christian Brabandt <cb@256bit.org> parents: 33372 diff changeset	219 <
7c9124711f99 patch 9.0.1948: Vim9: object variable "this." should only be used in constructor Christian Brabandt <cb@256bit.org> parents: 33372 diff changeset	220 E1390
33351 a3bbd065fb87 runtime(doc): Vim9: Consistenly use class/object variable and class/object method in help (#13149) Christian Brabandt <cb@256bit.org> parents: 33286 diff changeset	221 Not only is this text you need to write, it also has the type of each
a3bbd065fb87 runtime(doc): Vim9: Consistenly use class/object variable and class/object method in help (#13149) Christian Brabandt <cb@256bit.org> parents: 33286 diff changeset	222 variables twice. Since this is so common a shorter way to write new() is
a3bbd065fb87 runtime(doc): Vim9: Consistenly use class/object variable and class/object method in help (#13149) Christian Brabandt <cb@256bit.org> parents: 33286 diff changeset	223 provided: >
31335 5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	224
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	225 def new(this.lnum, this.col)
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	226 enddef
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	227
33351 a3bbd065fb87 runtime(doc): Vim9: Consistenly use class/object variable and class/object method in help (#13149) Christian Brabandt <cb@256bit.org> parents: 33286 diff changeset	228 The semantics are easy to understand: Providing the object variable name,
31335 5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	229 including "this.", as the argument to new() means the value provided in the
33351 a3bbd065fb87 runtime(doc): Vim9: Consistenly use class/object variable and class/object method in help (#13149) Christian Brabandt <cb@256bit.org> parents: 33286 diff changeset	230 new() call is assigned to that object variable. This mechanism comes from the
31885 cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	231 Dart language.
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	232
33351 a3bbd065fb87 runtime(doc): Vim9: Consistenly use class/object variable and class/object method in help (#13149) Christian Brabandt <cb@256bit.org> parents: 33286 diff changeset	233 Putting together this way of using new() and making the variables public
a3bbd065fb87 runtime(doc): Vim9: Consistenly use class/object variable and class/object method in help (#13149) Christian Brabandt <cb@256bit.org> parents: 33286 diff changeset	234 results in a much shorter class definition than what we started with: >
31885 cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	235
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	236 class TextPosition
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	237 public this.lnum: number
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	238 public this.col: number
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	239
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	240 def new(this.lnum, this.col)
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	241 enddef
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	242
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	243 def SetPosition(lnum: number, col: number)
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	244 this.lnum = lnum
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	245 this.col = col
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	246 enddef
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	247 endclass
31335 5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	248
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	249 The sequence of constructing a new object is:
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	250 1. Memory is allocated and cleared. All values are zero/false/empty.
33351 a3bbd065fb87 runtime(doc): Vim9: Consistenly use class/object variable and class/object method in help (#13149) Christian Brabandt <cb@256bit.org> parents: 33286 diff changeset	251 2. For each declared object variable that has an initializer, the expression
a3bbd065fb87 runtime(doc): Vim9: Consistenly use class/object variable and class/object method in help (#13149) Christian Brabandt <cb@256bit.org> parents: 33286 diff changeset	252 is evaluated and assigned to the variable. This happens in the sequence
a3bbd065fb87 runtime(doc): Vim9: Consistenly use class/object variable and class/object method in help (#13149) Christian Brabandt <cb@256bit.org> parents: 33286 diff changeset	253 the variables are declared in the class.
31335 5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	254 3. Arguments in the new() method in the "this.name" form are assigned.
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	255 4. The body of the new() method is executed.
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	256
31885 cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	257 If the class extends a parent class, the same thing happens. In the second
33351 a3bbd065fb87 runtime(doc): Vim9: Consistenly use class/object variable and class/object method in help (#13149) Christian Brabandt <cb@256bit.org> parents: 33286 diff changeset	258 step the object variables of the parent class are initialized first. There is
a3bbd065fb87 runtime(doc): Vim9: Consistenly use class/object variable and class/object method in help (#13149) Christian Brabandt <cb@256bit.org> parents: 33286 diff changeset	259 no need to call "super()" or "new()" on the parent.
31335 5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	260
33385 b5ad84fdc702 patch 9.0.1951: Vim9: hard to debug vim9_class errors from CI Christian Brabandt <cb@256bit.org> parents: 33383 diff changeset	261 E1365
32903 54c01bb98b8e patch 9.0.1760: vim9 class problem with new() constructor Christian Brabandt <cb@256bit.org> parents: 32294 diff changeset	262 When defining the new() method the return type should not be specified. It
54c01bb98b8e patch 9.0.1760: vim9 class problem with new() constructor Christian Brabandt <cb@256bit.org> parents: 32294 diff changeset	263 always returns an object of the class.
54c01bb98b8e patch 9.0.1760: vim9 class problem with new() constructor Christian Brabandt <cb@256bit.org> parents: 32294 diff changeset	264
33385 b5ad84fdc702 patch 9.0.1951: Vim9: hard to debug vim9_class errors from CI Christian Brabandt <cb@256bit.org> parents: 33383 diff changeset	265 E1386
b5ad84fdc702 patch 9.0.1951: Vim9: hard to debug vim9_class errors from CI Christian Brabandt <cb@256bit.org> parents: 33383 diff changeset	266 When invoking an object method, the method name should be preceded by the
b5ad84fdc702 patch 9.0.1951: Vim9: hard to debug vim9_class errors from CI Christian Brabandt <cb@256bit.org> parents: 33383 diff changeset	267 object variable name. A object method cannot be invoked using the class
b5ad84fdc702 patch 9.0.1951: Vim9: hard to debug vim9_class errors from CI Christian Brabandt <cb@256bit.org> parents: 33383 diff changeset	268 name.
b5ad84fdc702 patch 9.0.1951: Vim9: hard to debug vim9_class errors from CI Christian Brabandt <cb@256bit.org> parents: 33383 diff changeset	269
31335 5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	270 ==============================================================================
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	271
33286 0c3553cfe22e patch 9.0.1909: Vim9: problem calling class method from other class Christian Brabandt <cb@256bit.org> parents: 33217 diff changeset	272 3. Class Variables and Methods Vim9-class-member
31885 cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	273
33286 0c3553cfe22e patch 9.0.1909: Vim9: problem calling class method from other class Christian Brabandt <cb@256bit.org> parents: 33217 diff changeset	274 :static E1337 E1338 E1368
31885 cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	275 Class members are declared with "static". They are used by the name without a
33286 0c3553cfe22e patch 9.0.1909: Vim9: problem calling class method from other class Christian Brabandt <cb@256bit.org> parents: 33217 diff changeset	276 prefix in the class where they are defined: >
31885 cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	277
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	278 class OtherThing
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	279 this.size: number
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	280 static totalSize: number
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	281
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	282 def new(this.size)
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	283 totalSize += this.size
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	284 enddef
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	285 endclass
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	286 < E1340 E1341
33351 a3bbd065fb87 runtime(doc): Vim9: Consistenly use class/object variable and class/object method in help (#13149) Christian Brabandt <cb@256bit.org> parents: 33286 diff changeset	287 Since the name is used as-is, shadowing the name by a method argument name
31885 cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	288 or local variable name is not allowed.
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	289
33385 b5ad84fdc702 patch 9.0.1951: Vim9: hard to debug vim9_class errors from CI Christian Brabandt <cb@256bit.org> parents: 33383 diff changeset	290 E1374 E1375 E1384 E1385
33286 0c3553cfe22e patch 9.0.1909: Vim9: problem calling class method from other class Christian Brabandt <cb@256bit.org> parents: 33217 diff changeset	291 To access a class member outside of the class where it is defined, the class
0c3553cfe22e patch 9.0.1909: Vim9: problem calling class method from other class Christian Brabandt <cb@256bit.org> parents: 33217 diff changeset	292 name prefix must be used. A class member cannot be accessed using an object.
0c3553cfe22e patch 9.0.1909: Vim9: problem calling class method from other class Christian Brabandt <cb@256bit.org> parents: 33217 diff changeset	293
31885 cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	294 Just like object members the access can be made private by using an underscore
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	295 as the first character in the name, and it can be made public by prefixing
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	296 "public": >
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	297
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	298 class OtherThing
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	299 static total: number # anybody can read, only class can write
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	300 static _sum: number # only class can read and write
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	301 public static result: number # anybody can read and write
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	302 endclass
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	303 <
33286 0c3553cfe22e patch 9.0.1909: Vim9: problem calling class method from other class Christian Brabandt <cb@256bit.org> parents: 33217 diff changeset	304 class-method
0c3553cfe22e patch 9.0.1909: Vim9: problem calling class method from other class Christian Brabandt <cb@256bit.org> parents: 33217 diff changeset	305 Class methods are also declared with "static". They can use the class
0c3553cfe22e patch 9.0.1909: Vim9: problem calling class method from other class Christian Brabandt <cb@256bit.org> parents: 33217 diff changeset	306 variables but they have no access to the object variables, they cannot use the
0c3553cfe22e patch 9.0.1909: Vim9: problem calling class method from other class Christian Brabandt <cb@256bit.org> parents: 33217 diff changeset	307 "this" keyword.
0c3553cfe22e patch 9.0.1909: Vim9: problem calling class method from other class Christian Brabandt <cb@256bit.org> parents: 33217 diff changeset	308 >
31885 cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	309 class OtherThing
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	310 this.size: number
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	311 static totalSize: number
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	312
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	313 # Clear the total size and return the value it had before.
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	314 static def ClearTotalSize(): number
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	315 var prev = totalSize
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	316 totalSize = 0
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	317 return prev
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	318 enddef
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	319 endclass
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	320
33286 0c3553cfe22e patch 9.0.1909: Vim9: problem calling class method from other class Christian Brabandt <cb@256bit.org> parents: 33217 diff changeset	321 Inside the class the class method can be called by name directly, outside the
0c3553cfe22e patch 9.0.1909: Vim9: problem calling class method from other class Christian Brabandt <cb@256bit.org> parents: 33217 diff changeset	322 class the class name must be prefixed: `OtherThing.ClearTotalSize()`. To use
0c3553cfe22e patch 9.0.1909: Vim9: problem calling class method from other class Christian Brabandt <cb@256bit.org> parents: 33217 diff changeset	323 a super class method in a child class, the class name must be prefixed.
31885 cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	324
33025 1d18c7fe609f patch 9.0.1804: Vim9: no support for private object methods Christian Brabandt <cb@256bit.org> parents: 32960 diff changeset	325 Just like object methods the access can be made private by using an underscore
1d18c7fe609f patch 9.0.1804: Vim9: no support for private object methods Christian Brabandt <cb@256bit.org> parents: 32960 diff changeset	326 as the first character in the method name: >
1d18c7fe609f patch 9.0.1804: Vim9: no support for private object methods Christian Brabandt <cb@256bit.org> parents: 32960 diff changeset	327
1d18c7fe609f patch 9.0.1804: Vim9: no support for private object methods Christian Brabandt <cb@256bit.org> parents: 32960 diff changeset	328 class OtherThing
1d18c7fe609f patch 9.0.1804: Vim9: no support for private object methods Christian Brabandt <cb@256bit.org> parents: 32960 diff changeset	329 static def _Foo()
1d18c7fe609f patch 9.0.1804: Vim9: no support for private object methods Christian Brabandt <cb@256bit.org> parents: 32960 diff changeset	330 echo "Foo"
1d18c7fe609f patch 9.0.1804: Vim9: no support for private object methods Christian Brabandt <cb@256bit.org> parents: 32960 diff changeset	331 enddef
1d18c7fe609f patch 9.0.1804: Vim9: no support for private object methods Christian Brabandt <cb@256bit.org> parents: 32960 diff changeset	332 def Bar()
33286 0c3553cfe22e patch 9.0.1909: Vim9: problem calling class method from other class Christian Brabandt <cb@256bit.org> parents: 33217 diff changeset	333 _Foo()
33025 1d18c7fe609f patch 9.0.1804: Vim9: no support for private object methods Christian Brabandt <cb@256bit.org> parents: 32960 diff changeset	334 enddef
1d18c7fe609f patch 9.0.1804: Vim9: no support for private object methods Christian Brabandt <cb@256bit.org> parents: 32960 diff changeset	335 endclass
33068 d42927c6e556 patch 9.0.1821: Vim9 constructors are always static Christian Brabandt <cb@256bit.org> parents: 33025 diff changeset	336 <
d42927c6e556 patch 9.0.1821: Vim9 constructors are always static Christian Brabandt <cb@256bit.org> parents: 33025 diff changeset	337 E1370
d42927c6e556 patch 9.0.1821: Vim9 constructors are always static Christian Brabandt <cb@256bit.org> parents: 33025 diff changeset	338 Note that constructors cannot be declared as "static", because they always
d42927c6e556 patch 9.0.1821: Vim9 constructors are always static Christian Brabandt <cb@256bit.org> parents: 33025 diff changeset	339 are.
33025 1d18c7fe609f patch 9.0.1804: Vim9: no support for private object methods Christian Brabandt <cb@256bit.org> parents: 32960 diff changeset	340
33286 0c3553cfe22e patch 9.0.1909: Vim9: problem calling class method from other class Christian Brabandt <cb@256bit.org> parents: 33217 diff changeset	341 To access the class methods and class variables of a super class in an
0c3553cfe22e patch 9.0.1909: Vim9: problem calling class method from other class Christian Brabandt <cb@256bit.org> parents: 33217 diff changeset	342 extended class, the class name prefix should be used just as from anywhere
0c3553cfe22e patch 9.0.1909: Vim9: problem calling class method from other class Christian Brabandt <cb@256bit.org> parents: 33217 diff changeset	343 outside of the defining class: >
0c3553cfe22e patch 9.0.1909: Vim9: problem calling class method from other class Christian Brabandt <cb@256bit.org> parents: 33217 diff changeset	344
0c3553cfe22e patch 9.0.1909: Vim9: problem calling class method from other class Christian Brabandt <cb@256bit.org> parents: 33217 diff changeset	345 vim9script
0c3553cfe22e patch 9.0.1909: Vim9: problem calling class method from other class Christian Brabandt <cb@256bit.org> parents: 33217 diff changeset	346 class Vehicle
0c3553cfe22e patch 9.0.1909: Vim9: problem calling class method from other class Christian Brabandt <cb@256bit.org> parents: 33217 diff changeset	347 static nextID: number = 1000
0c3553cfe22e patch 9.0.1909: Vim9: problem calling class method from other class Christian Brabandt <cb@256bit.org> parents: 33217 diff changeset	348 static def GetID(): number
0c3553cfe22e patch 9.0.1909: Vim9: problem calling class method from other class Christian Brabandt <cb@256bit.org> parents: 33217 diff changeset	349 nextID += 1
0c3553cfe22e patch 9.0.1909: Vim9: problem calling class method from other class Christian Brabandt <cb@256bit.org> parents: 33217 diff changeset	350 return nextID
0c3553cfe22e patch 9.0.1909: Vim9: problem calling class method from other class Christian Brabandt <cb@256bit.org> parents: 33217 diff changeset	351 enddef
0c3553cfe22e patch 9.0.1909: Vim9: problem calling class method from other class Christian Brabandt <cb@256bit.org> parents: 33217 diff changeset	352 endclass
0c3553cfe22e patch 9.0.1909: Vim9: problem calling class method from other class Christian Brabandt <cb@256bit.org> parents: 33217 diff changeset	353 class Car extends Vehicle
0c3553cfe22e patch 9.0.1909: Vim9: problem calling class method from other class Christian Brabandt <cb@256bit.org> parents: 33217 diff changeset	354 this.myID: number
0c3553cfe22e patch 9.0.1909: Vim9: problem calling class method from other class Christian Brabandt <cb@256bit.org> parents: 33217 diff changeset	355 def new()
0c3553cfe22e patch 9.0.1909: Vim9: problem calling class method from other class Christian Brabandt <cb@256bit.org> parents: 33217 diff changeset	356 this.myID = Vehicle.GetID()
0c3553cfe22e patch 9.0.1909: Vim9: problem calling class method from other class Christian Brabandt <cb@256bit.org> parents: 33217 diff changeset	357 enddef
0c3553cfe22e patch 9.0.1909: Vim9: problem calling class method from other class Christian Brabandt <cb@256bit.org> parents: 33217 diff changeset	358 endclass
0c3553cfe22e patch 9.0.1909: Vim9: problem calling class method from other class Christian Brabandt <cb@256bit.org> parents: 33217 diff changeset	359 <
0c3553cfe22e patch 9.0.1909: Vim9: problem calling class method from other class Christian Brabandt <cb@256bit.org> parents: 33217 diff changeset	360 Class variables and methods are not inherited by a child class. A child class
0c3553cfe22e patch 9.0.1909: Vim9: problem calling class method from other class Christian Brabandt <cb@256bit.org> parents: 33217 diff changeset	361 can declare a static variable or a method with the same name as the one in the
0c3553cfe22e patch 9.0.1909: Vim9: problem calling class method from other class Christian Brabandt <cb@256bit.org> parents: 33217 diff changeset	362 super class. Depending on the class where the member is used the
0c3553cfe22e patch 9.0.1909: Vim9: problem calling class method from other class Christian Brabandt <cb@256bit.org> parents: 33217 diff changeset	363 corresponding class member will be used. The type of the class member in a
0c3553cfe22e patch 9.0.1909: Vim9: problem calling class method from other class Christian Brabandt <cb@256bit.org> parents: 33217 diff changeset	364 child class can be different from that in the super class.
0c3553cfe22e patch 9.0.1909: Vim9: problem calling class method from other class Christian Brabandt <cb@256bit.org> parents: 33217 diff changeset	365
31885 cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	366 ==============================================================================
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	367
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	368 4. Using an abstract class Vim9-abstract-class
31335 5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	369
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	370 An abstract class forms the base for at least one sub-class. In the class
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	371 model one often finds that a few classes have the same properties that can be
31885 cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	372 shared, but a class with these properties does not have enough state to create
31335 5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	373 an object from. A sub-class must extend the abstract class and add the
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	374 missing state and/or methods before it can be used to create objects for.
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	375
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	376 For example, a Shape class could store a color and thickness. You cannot
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	377 create a Shape object, it is missing the information about what kind of shape
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	378 it is. The Shape class functions as the base for a Square and a Triangle
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	379 class, for which objects can be created. Example: >
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	380
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	381 abstract class Shape
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	382 this.color = Color.Black
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	383 this.thickness = 10
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	384 endclass
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	385
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	386 class Square extends Shape
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	387 this.size: number
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	388
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	389 def new(this.size)
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	390 enddef
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	391 endclass
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	392
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	393 class Triangle extends Shape
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	394 this.base: number
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	395 this.height: number
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	396
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	397 def new(this.base, this.height)
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	398 enddef
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	399 endclass
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	400 <
31885 cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	401 An abstract class is defined the same way as a normal class, except that it
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	402 does not have any new() method. E1359
31335 5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	403
33286 0c3553cfe22e patch 9.0.1909: Vim9: problem calling class method from other class Christian Brabandt <cb@256bit.org> parents: 33217 diff changeset	404 abstract-method E1371 E1372
33217 499ba27ba0f6 patch 9.0.1885: Vim9: no support for abstract methods Christian Brabandt <cb@256bit.org> parents: 33068 diff changeset	405 An abstract method can be defined in an abstract class by using the "abstract"
33351 a3bbd065fb87 runtime(doc): Vim9: Consistenly use class/object variable and class/object method in help (#13149) Christian Brabandt <cb@256bit.org> parents: 33286 diff changeset	406 prefix when defining the method: >
33217 499ba27ba0f6 patch 9.0.1885: Vim9: no support for abstract methods Christian Brabandt <cb@256bit.org> parents: 33068 diff changeset	407
499ba27ba0f6 patch 9.0.1885: Vim9: no support for abstract methods Christian Brabandt <cb@256bit.org> parents: 33068 diff changeset	408 abstract class Shape
499ba27ba0f6 patch 9.0.1885: Vim9: no support for abstract methods Christian Brabandt <cb@256bit.org> parents: 33068 diff changeset	409 abstract def Draw()
33286 0c3553cfe22e patch 9.0.1909: Vim9: problem calling class method from other class Christian Brabandt <cb@256bit.org> parents: 33217 diff changeset	410 abstract static def SetColor()
33217 499ba27ba0f6 patch 9.0.1885: Vim9: no support for abstract methods Christian Brabandt <cb@256bit.org> parents: 33068 diff changeset	411 endclass
33286 0c3553cfe22e patch 9.0.1909: Vim9: problem calling class method from other class Christian Brabandt <cb@256bit.org> parents: 33217 diff changeset	412 <
0c3553cfe22e patch 9.0.1909: Vim9: problem calling class method from other class Christian Brabandt <cb@256bit.org> parents: 33217 diff changeset	413 E1373
33217 499ba27ba0f6 patch 9.0.1885: Vim9: no support for abstract methods Christian Brabandt <cb@256bit.org> parents: 33068 diff changeset	414 A class extending the abstract class must implement all the abstract methods.
33286 0c3553cfe22e patch 9.0.1909: Vim9: problem calling class method from other class Christian Brabandt <cb@256bit.org> parents: 33217 diff changeset	415 The signature (arguments, argument types and return type) must be exactly the
0c3553cfe22e patch 9.0.1909: Vim9: problem calling class method from other class Christian Brabandt <cb@256bit.org> parents: 33217 diff changeset	416 same. Class methods in an abstract class can also be abstract methods.
31335 5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	417
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	418 ==============================================================================
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	419
31885 cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	420 5. Using an interface Vim9-using-interface
31335 5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	421
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	422 The example above with Shape, Square and Triangle can be made more useful if
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	423 we add a method to compute the surface of the object. For that we create the
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	424 interface called HasSurface, which specifies one method Surface() that returns
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	425 a number. This example extends the one above: >
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	426
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	427 abstract class Shape
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	428 this.color = Color.Black
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	429 this.thickness = 10
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	430 endclass
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	431
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	432 interface HasSurface
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	433 def Surface(): number
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	434 endinterface
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	435
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	436 class Square extends Shape implements HasSurface
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	437 this.size: number
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	438
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	439 def new(this.size)
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	440 enddef
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	441
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	442 def Surface(): number
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	443 return this.size * this.size
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	444 enddef
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	445 endclass
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	446
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	447 class Triangle extends Shape implements HasSurface
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	448 this.base: number
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	449 this.height: number
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	450
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	451 def new(this.base, this.height)
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	452 enddef
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	453
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	454 def Surface(): number
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	455 return this.base * this.height / 2
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	456 enddef
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	457 endclass
33286 0c3553cfe22e patch 9.0.1909: Vim9: problem calling class method from other class Christian Brabandt <cb@256bit.org> parents: 33217 diff changeset	458 <
0c3553cfe22e patch 9.0.1909: Vim9: problem calling class method from other class Christian Brabandt <cb@256bit.org> parents: 33217 diff changeset	459 E1348 E1349 E1367 E1382 E1383
31671 5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	460 If a class declares to implement an interface, all the items specified in the
33286 0c3553cfe22e patch 9.0.1909: Vim9: problem calling class method from other class Christian Brabandt <cb@256bit.org> parents: 33217 diff changeset	461 interface must appear in the class, with the same types.
31671 5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	462
31335 5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	463 The interface name can be used as a type: >
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	464
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	465 var shapes: list<HasSurface> = [
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	466 Square.new(12),
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	467 Triangle.new(8, 15),
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	468 ]
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	469 for shape in shapes
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	470 echo $'the surface is {shape.Surface()}'
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	471 endfor
33286 0c3553cfe22e patch 9.0.1909: Vim9: problem calling class method from other class Christian Brabandt <cb@256bit.org> parents: 33217 diff changeset	472 <
33372 3e9a91624b40 patch 9.0.1945: Vim9: missing support for ro-vars in interface Christian Brabandt <cb@256bit.org> parents: 33351 diff changeset	473 E1378 E1379 E1380 E1387
3e9a91624b40 patch 9.0.1945: Vim9: missing support for ro-vars in interface Christian Brabandt <cb@256bit.org> parents: 33351 diff changeset	474 An interface can contain only object methods and read-only object variables.
3e9a91624b40 patch 9.0.1945: Vim9: missing support for ro-vars in interface Christian Brabandt <cb@256bit.org> parents: 33351 diff changeset	475 An interface cannot contain read-write and private object variables, private
3e9a91624b40 patch 9.0.1945: Vim9: missing support for ro-vars in interface Christian Brabandt <cb@256bit.org> parents: 33351 diff changeset	476 object methods, class variables and class methods.
31335 5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	477
33286 0c3553cfe22e patch 9.0.1909: Vim9: problem calling class method from other class Christian Brabandt <cb@256bit.org> parents: 33217 diff changeset	478 An interface can extend another interface using "extends". The sub-interface
0c3553cfe22e patch 9.0.1909: Vim9: problem calling class method from other class Christian Brabandt <cb@256bit.org> parents: 33217 diff changeset	479 inherits all the instance variables and methods from the super interface.
31335 5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	480
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	481 ==============================================================================
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	482
31885 cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	483 6. More class details Vim9-class Class class
31335 5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	484
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	485 Defining a class ~
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	486 :class :endclass :abstract
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	487 A class is defined between `:class` and `:endclass`. The whole class is
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	488 defined in one script file. It is not possible to add to a class later.
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	489
31430 e5e95e8c78a7 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31396 diff changeset	490 A class can only be defined in a \|Vim9\| script file. E1316
31396 307f68a41b03 patch 9.0.1031: Vim9 class is not implemented yet Bram Moolenaar <Bram@vim.org> parents: 31335 diff changeset	491 A class cannot be defined inside a function.
307f68a41b03 patch 9.0.1031: Vim9 class is not implemented yet Bram Moolenaar <Bram@vim.org> parents: 31335 diff changeset	492
31335 5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	493 It is possible to define more than one class in a script file. Although it
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	494 usually is better to export only one main class. It can be useful to define
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	495 types, enums and helper classes though.
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	496
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	497 The `:abstract` keyword may be prefixed and `:export` may be used. That gives
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	498 these variants: >
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	499
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	500 class ClassName
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	501 endclass
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	502
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	503 export class ClassName
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	504 endclass
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	505
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	506 abstract class ClassName
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	507 endclass
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	508
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	509 export abstract class ClassName
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	510 endclass
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	511 <
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	512 E1314
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	513 The class name should be CamelCased. It must start with an uppercase letter.
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	514 That avoids clashing with builtin types.
31430 e5e95e8c78a7 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31396 diff changeset	515 E1315
31335 5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	516 After the class name these optional items can be used. Each can appear only
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	517 once. They can appear in any order, although this order is recommended: >
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	518 extends ClassName
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	519 implements InterfaceName, OtherInterface
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	520 specifies SomeInterface
33286 0c3553cfe22e patch 9.0.1909: Vim9: problem calling class method from other class Christian Brabandt <cb@256bit.org> parents: 33217 diff changeset	521 < E1355 E1369
33351 a3bbd065fb87 runtime(doc): Vim9: Consistenly use class/object variable and class/object method in help (#13149) Christian Brabandt <cb@256bit.org> parents: 33286 diff changeset	522 Each variable and method name can be used only once. It is not possible to
a3bbd065fb87 runtime(doc): Vim9: Consistenly use class/object variable and class/object method in help (#13149) Christian Brabandt <cb@256bit.org> parents: 33286 diff changeset	523 define a method with the same name and different type of arguments. It is not
a3bbd065fb87 runtime(doc): Vim9: Consistenly use class/object variable and class/object method in help (#13149) Christian Brabandt <cb@256bit.org> parents: 33286 diff changeset	524 possible to use a public and private member variable with the same name. A
a3bbd065fb87 runtime(doc): Vim9: Consistenly use class/object variable and class/object method in help (#13149) Christian Brabandt <cb@256bit.org> parents: 33286 diff changeset	525 object variable name used in a super class cannot be reused in a child class.
31885 cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	526
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	527
33351 a3bbd065fb87 runtime(doc): Vim9: Consistenly use class/object variable and class/object method in help (#13149) Christian Brabandt <cb@256bit.org> parents: 33286 diff changeset	528 Object Variable Initialization ~
a3bbd065fb87 runtime(doc): Vim9: Consistenly use class/object variable and class/object method in help (#13149) Christian Brabandt <cb@256bit.org> parents: 33286 diff changeset	529 If the type of a variable is not explicitly specified in a class, then it is
a3bbd065fb87 runtime(doc): Vim9: Consistenly use class/object variable and class/object method in help (#13149) Christian Brabandt <cb@256bit.org> parents: 33286 diff changeset	530 set to "any" during class definition. When an object is instantiated from the
a3bbd065fb87 runtime(doc): Vim9: Consistenly use class/object variable and class/object method in help (#13149) Christian Brabandt <cb@256bit.org> parents: 33286 diff changeset	531 class, then the type of the variable is set.
32960 d5c05e15cf81 patch 9.0.1780: Vim9 type not defined during object creation Christian Brabandt <cb@256bit.org> parents: 32903 diff changeset	532
d5c05e15cf81 patch 9.0.1780: Vim9 type not defined during object creation Christian Brabandt <cb@256bit.org> parents: 32903 diff changeset	533
31885 cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	534 Extending a class ~
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	535 extends
31671 5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	536 A class can extend one other class. E1352 E1353 E1354
31885 cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	537 The basic idea is to build on top of an existing class, add properties to it.
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	538
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	539 The extended class is called the "base class" or "super class". The new class
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	540 is called the "child class".
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	541
33351 a3bbd065fb87 runtime(doc): Vim9: Consistenly use class/object variable and class/object method in help (#13149) Christian Brabandt <cb@256bit.org> parents: 33286 diff changeset	542 Object variables from the base class are all taken over by the child class. It
31885 cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	543 is not possible to override them (unlike some other languages).
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	544
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	545 E1356 E1357 E1358
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	546 Object methods of the base class can be overruled. The signature (arguments,
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	547 argument types and return type) must be exactly the same. The method of the
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	548 base class can be called by prefixing "super.".
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	549
33286 0c3553cfe22e patch 9.0.1909: Vim9: problem calling class method from other class Christian Brabandt <cb@256bit.org> parents: 33217 diff changeset	550 E1377
0c3553cfe22e patch 9.0.1909: Vim9: problem calling class method from other class Christian Brabandt <cb@256bit.org> parents: 33217 diff changeset	551 The access level of a method (public or private) in a child class should be
0c3553cfe22e patch 9.0.1909: Vim9: problem calling class method from other class Christian Brabandt <cb@256bit.org> parents: 33217 diff changeset	552 the same as the super class.
0c3553cfe22e patch 9.0.1909: Vim9: problem calling class method from other class Christian Brabandt <cb@256bit.org> parents: 33217 diff changeset	553
31885 cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	554 Other object methods of the base class are taken over by the child class.
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	555
33351 a3bbd065fb87 runtime(doc): Vim9: Consistenly use class/object variable and class/object method in help (#13149) Christian Brabandt <cb@256bit.org> parents: 33286 diff changeset	556 Class methods, including methods starting with "new", can be overruled, like
a3bbd065fb87 runtime(doc): Vim9: Consistenly use class/object variable and class/object method in help (#13149) Christian Brabandt <cb@256bit.org> parents: 33286 diff changeset	557 with object methods. The method on the base class can be called by prefixing
a3bbd065fb87 runtime(doc): Vim9: Consistenly use class/object variable and class/object method in help (#13149) Christian Brabandt <cb@256bit.org> parents: 33286 diff changeset	558 the name of the class (for class methods) or "super.".
31885 cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	559
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	560 Unlike other languages, the constructor of the base class does not need to be
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	561 invoked. In fact, it cannot be invoked. If some initialization from the base
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	562 class also needs to be done in a child class, put it in an object method and
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	563 call that method from every constructor().
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	564
33351 a3bbd065fb87 runtime(doc): Vim9: Consistenly use class/object variable and class/object method in help (#13149) Christian Brabandt <cb@256bit.org> parents: 33286 diff changeset	565 If the base class did not specify a new() method then one was automatically
a3bbd065fb87 runtime(doc): Vim9: Consistenly use class/object variable and class/object method in help (#13149) Christian Brabandt <cb@256bit.org> parents: 33286 diff changeset	566 created. This method will not be taken over by the child class. The child
a3bbd065fb87 runtime(doc): Vim9: Consistenly use class/object variable and class/object method in help (#13149) Christian Brabandt <cb@256bit.org> parents: 33286 diff changeset	567 class can define its own new() method, or, if there isn't one, a new() method
a3bbd065fb87 runtime(doc): Vim9: Consistenly use class/object variable and class/object method in help (#13149) Christian Brabandt <cb@256bit.org> parents: 33286 diff changeset	568 will be added automatically.
31885 cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	569
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	570
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	571 A class implementing an interface ~
33372 3e9a91624b40 patch 9.0.1945: Vim9: missing support for ro-vars in interface Christian Brabandt <cb@256bit.org> parents: 33351 diff changeset	572 implements E1346 E1347 E1389
31671 5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	573 A class can implement one or more interfaces. The "implements" keyword can
5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	574 only appear once E1350 . Multiple interfaces can be specified, separated by
5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	575 commas. Each interface name can appear only once. E1351
31885 cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	576
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	577
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	578 A class defining an interface ~
31335 5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	579 specifies
33351 a3bbd065fb87 runtime(doc): Vim9: Consistenly use class/object variable and class/object method in help (#13149) Christian Brabandt <cb@256bit.org> parents: 33286 diff changeset	580 A class can declare its interface, the object variables and methods, with a
31335 5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	581 named interface. This avoids the need for separately specifying the
31396 307f68a41b03 patch 9.0.1031: Vim9 class is not implemented yet Bram Moolenaar <Bram@vim.org> parents: 31335 diff changeset	582 interface, which is often done in many languages, especially Java.
31335 5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	583
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	584
31430 e5e95e8c78a7 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31396 diff changeset	585 Items in a class ~
33372 3e9a91624b40 patch 9.0.1945: Vim9: missing support for ro-vars in interface Christian Brabandt <cb@256bit.org> parents: 33351 diff changeset	586 E1318 E1325 E1388
32061 b2412874362f Update runtime files Bram Moolenaar <Bram@vim.org> parents: 32004 diff changeset	587 Inside a class, in between `:class` and `:endclass`, these items can appear:
33351 a3bbd065fb87 runtime(doc): Vim9: Consistenly use class/object variable and class/object method in help (#13149) Christian Brabandt <cb@256bit.org> parents: 33286 diff changeset	588 - An object variable declaration: >
a3bbd065fb87 runtime(doc): Vim9: Consistenly use class/object variable and class/object method in help (#13149) Christian Brabandt <cb@256bit.org> parents: 33286 diff changeset	589 this._privateVariableName: memberType
a3bbd065fb87 runtime(doc): Vim9: Consistenly use class/object variable and class/object method in help (#13149) Christian Brabandt <cb@256bit.org> parents: 33286 diff changeset	590 this.readonlyVariableName: memberType
a3bbd065fb87 runtime(doc): Vim9: Consistenly use class/object variable and class/object method in help (#13149) Christian Brabandt <cb@256bit.org> parents: 33286 diff changeset	591 public this.readwriteVariableName: memberType
a3bbd065fb87 runtime(doc): Vim9: Consistenly use class/object variable and class/object method in help (#13149) Christian Brabandt <cb@256bit.org> parents: 33286 diff changeset	592 - A class variable declaration: >
a3bbd065fb87 runtime(doc): Vim9: Consistenly use class/object variable and class/object method in help (#13149) Christian Brabandt <cb@256bit.org> parents: 33286 diff changeset	593 static _privateClassVariableName: memberType
a3bbd065fb87 runtime(doc): Vim9: Consistenly use class/object variable and class/object method in help (#13149) Christian Brabandt <cb@256bit.org> parents: 33286 diff changeset	594 static readonlyClassVariableName: memberType
a3bbd065fb87 runtime(doc): Vim9: Consistenly use class/object variable and class/object method in help (#13149) Christian Brabandt <cb@256bit.org> parents: 33286 diff changeset	595 static public readwriteClassVariableName: memberType
31430 e5e95e8c78a7 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31396 diff changeset	596 - A constructor method: >
32004 a9b5ffbc0428 Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31885 diff changeset	597 def new(arguments)
a9b5ffbc0428 Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31885 diff changeset	598 def newName(arguments)
33286 0c3553cfe22e patch 9.0.1909: Vim9: problem calling class method from other class Christian Brabandt <cb@256bit.org> parents: 33217 diff changeset	599 - A class method: >
0c3553cfe22e patch 9.0.1909: Vim9: problem calling class method from other class Christian Brabandt <cb@256bit.org> parents: 33217 diff changeset	600 static def SomeMethod(arguments)
0c3553cfe22e patch 9.0.1909: Vim9: problem calling class method from other class Christian Brabandt <cb@256bit.org> parents: 33217 diff changeset	601 static def _PrivateMethod(arguments)
31430 e5e95e8c78a7 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31396 diff changeset	602 - An object method: >
32004 a9b5ffbc0428 Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31885 diff changeset	603 def SomeMethod(arguments)
33286 0c3553cfe22e patch 9.0.1909: Vim9: problem calling class method from other class Christian Brabandt <cb@256bit.org> parents: 33217 diff changeset	604 def _PrivateMethod(arguments)
0c3553cfe22e patch 9.0.1909: Vim9: problem calling class method from other class Christian Brabandt <cb@256bit.org> parents: 33217 diff changeset	605
33351 a3bbd065fb87 runtime(doc): Vim9: Consistenly use class/object variable and class/object method in help (#13149) Christian Brabandt <cb@256bit.org> parents: 33286 diff changeset	606 For the object variable the type must be specified. The best way is to do
a3bbd065fb87 runtime(doc): Vim9: Consistenly use class/object variable and class/object method in help (#13149) Christian Brabandt <cb@256bit.org> parents: 33286 diff changeset	607 this explicitly with ": {type}". For simple types you can also use an
a3bbd065fb87 runtime(doc): Vim9: Consistenly use class/object variable and class/object method in help (#13149) Christian Brabandt <cb@256bit.org> parents: 33286 diff changeset	608 initializer, such as "= 123", and Vim will see that the type is a number.
a3bbd065fb87 runtime(doc): Vim9: Consistenly use class/object variable and class/object method in help (#13149) Christian Brabandt <cb@256bit.org> parents: 33286 diff changeset	609 Avoid doing this for more complex types and when the type will be incomplete.
a3bbd065fb87 runtime(doc): Vim9: Consistenly use class/object variable and class/object method in help (#13149) Christian Brabandt <cb@256bit.org> parents: 33286 diff changeset	610 For example: >
31579 7d68a90cbf5c Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31441 diff changeset	611 this.nameList = []
7d68a90cbf5c Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31441 diff changeset	612 This specifies a list, but the item type is unknown. Better use: >
7d68a90cbf5c Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31441 diff changeset	613 this.nameList: list<string>
7d68a90cbf5c Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31441 diff changeset	614 The initialization isn't needed, the list is empty by default.
7d68a90cbf5c Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31441 diff changeset	615 E1330
7d68a90cbf5c Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31441 diff changeset	616 Some types cannot be used, such as "void", "null" and "v:none".
31430 e5e95e8c78a7 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31396 diff changeset	617
e5e95e8c78a7 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31396 diff changeset	618
31335 5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	619 Defining an interface ~
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	620 :interface :endinterface
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	621 An interface is defined between `:interface` and `:endinterface`. It may be
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	622 prefixed with `:export`: >
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	623
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	624 interface InterfaceName
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	625 endinterface
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	626
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	627 export interface InterfaceName
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	628 endinterface
31671 5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	629 < E1344
33351 a3bbd065fb87 runtime(doc): Vim9: Consistenly use class/object variable and class/object method in help (#13149) Christian Brabandt <cb@256bit.org> parents: 33286 diff changeset	630 An interface can declare object variables, just like in a class but without
a3bbd065fb87 runtime(doc): Vim9: Consistenly use class/object variable and class/object method in help (#13149) Christian Brabandt <cb@256bit.org> parents: 33286 diff changeset	631 any initializer.
31671 5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	632 E1345
31335 5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	633 An interface can declare methods with `:def`, including the arguments and
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	634 return type, but without the body and without `:enddef`. Example: >
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	635
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	636 interface HasSurface
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	637 this.size: number
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	638 def Surface(): number
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	639 endinterface
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	640
31671 5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	641 An interface name must start with an uppercase letter. E1343
31335 5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	642 The "Has" prefix can be used to make it easier to guess this is an interface
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	643 name, with a hint about what it provides.
31671 5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	644 An interface can only be defined in a \|Vim9\| script file. E1342
33286 0c3553cfe22e patch 9.0.1909: Vim9: problem calling class method from other class Christian Brabandt <cb@256bit.org> parents: 33217 diff changeset	645 An interface cannot "implement" another interface but it can "extend" another
0c3553cfe22e patch 9.0.1909: Vim9: problem calling class method from other class Christian Brabandt <cb@256bit.org> parents: 33217 diff changeset	646 interface. E1381
31335 5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	647
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	648
32004 a9b5ffbc0428 Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31885 diff changeset	649 null object ~
a9b5ffbc0428 Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31885 diff changeset	650
32061 b2412874362f Update runtime files Bram Moolenaar <Bram@vim.org> parents: 32004 diff changeset	651 When a variable is declared to have the type of an object, but it is not
32004 a9b5ffbc0428 Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31885 diff changeset	652 initialized, the value is null. When trying to use this null object Vim often
a9b5ffbc0428 Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31885 diff changeset	653 does not know what class was supposed to be used. Vim then cannot check if
33351 a3bbd065fb87 runtime(doc): Vim9: Consistenly use class/object variable and class/object method in help (#13149) Christian Brabandt <cb@256bit.org> parents: 33286 diff changeset	654 a variable name is correct and you will get an "Using a null object" error,
a3bbd065fb87 runtime(doc): Vim9: Consistenly use class/object variable and class/object method in help (#13149) Christian Brabandt <cb@256bit.org> parents: 33286 diff changeset	655 even when the variable name is invalid. E1360 E1362 E1363
32004 a9b5ffbc0428 Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31885 diff changeset	656
a9b5ffbc0428 Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31885 diff changeset	657
31335 5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	658 Default constructor ~
33383 5c12ca4dcd45 patch 9.0.1950: Vim9: error codes spread out Christian Brabandt <cb@256bit.org> parents: 33379 diff changeset	659 default-constructor
31335 5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	660 In case you define a class without a new() method, one will be automatically
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	661 defined. This default constructor will have arguments for all the object
33351 a3bbd065fb87 runtime(doc): Vim9: Consistenly use class/object variable and class/object method in help (#13149) Christian Brabandt <cb@256bit.org> parents: 33286 diff changeset	662 variables, in the order they were specified. Thus if your class looks like: >
31335 5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	663
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	664 class AutoNew
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	665 this.name: string
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	666 this.age: number
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	667 this.gender: Gender
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	668 endclass
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	669
33351 a3bbd065fb87 runtime(doc): Vim9: Consistenly use class/object variable and class/object method in help (#13149) Christian Brabandt <cb@256bit.org> parents: 33286 diff changeset	670 Then the default constructor will be: >
31335 5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	671
31441 e572ff386670 patch 9.0.1053: default constructor arguments are not optional Bram Moolenaar <Bram@vim.org> parents: 31430 diff changeset	672 def new(this.name = v:none, this.age = v:none, this.gender = v:none)
31335 5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	673 enddef
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	674
31441 e572ff386670 patch 9.0.1053: default constructor arguments are not optional Bram Moolenaar <Bram@vim.org> parents: 31430 diff changeset	675 The "= v:none" default values make the arguments optional. Thus you can also
e572ff386670 patch 9.0.1053: default constructor arguments are not optional Bram Moolenaar <Bram@vim.org> parents: 31430 diff changeset	676 call `new()` without any arguments. No assignment will happen and the default
33351 a3bbd065fb87 runtime(doc): Vim9: Consistenly use class/object variable and class/object method in help (#13149) Christian Brabandt <cb@256bit.org> parents: 33286 diff changeset	677 value for the object variables will be used. This is a more useful example,
31441 e572ff386670 patch 9.0.1053: default constructor arguments are not optional Bram Moolenaar <Bram@vim.org> parents: 31430 diff changeset	678 with default values: >
31430 e5e95e8c78a7 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31396 diff changeset	679
e5e95e8c78a7 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31396 diff changeset	680 class TextPosition
e5e95e8c78a7 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31396 diff changeset	681 this.lnum: number = 1
e5e95e8c78a7 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31396 diff changeset	682 this.col: number = 1
e5e95e8c78a7 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31396 diff changeset	683 endclass
e5e95e8c78a7 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31396 diff changeset	684
e5e95e8c78a7 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31396 diff changeset	685 If you want the constructor to have mandatory arguments, you need to write it
e5e95e8c78a7 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31396 diff changeset	686 yourself. For example, if for the AutoNew class above you insist on getting
e5e95e8c78a7 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31396 diff changeset	687 the name, you can define the constructor like this: >
e5e95e8c78a7 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31396 diff changeset	688
31441 e572ff386670 patch 9.0.1053: default constructor arguments are not optional Bram Moolenaar <Bram@vim.org> parents: 31430 diff changeset	689 def new(this.name, this.age = v:none, this.gender = v:none)
31430 e5e95e8c78a7 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31396 diff changeset	690 enddef
31441 e572ff386670 patch 9.0.1053: default constructor arguments are not optional Bram Moolenaar <Bram@vim.org> parents: 31430 diff changeset	691 < E1328
e572ff386670 patch 9.0.1053: default constructor arguments are not optional Bram Moolenaar <Bram@vim.org> parents: 31430 diff changeset	692 Note that you cannot use another default value than "v:none" here. If you
33351 a3bbd065fb87 runtime(doc): Vim9: Consistenly use class/object variable and class/object method in help (#13149) Christian Brabandt <cb@256bit.org> parents: 33286 diff changeset	693 want to initialize the object variables, do it where they are declared. This
31441 e572ff386670 patch 9.0.1053: default constructor arguments are not optional Bram Moolenaar <Bram@vim.org> parents: 31430 diff changeset	694 way you only need to look in one place for the default values.
31430 e5e95e8c78a7 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31396 diff changeset	695
33351 a3bbd065fb87 runtime(doc): Vim9: Consistenly use class/object variable and class/object method in help (#13149) Christian Brabandt <cb@256bit.org> parents: 33286 diff changeset	696 All object variables will be used in the default constructor, also private
31671 5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	697 access ones.
5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	698
33351 a3bbd065fb87 runtime(doc): Vim9: Consistenly use class/object variable and class/object method in help (#13149) Christian Brabandt <cb@256bit.org> parents: 33286 diff changeset	699 If the class extends another one, the object variables of that class will come
31671 5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	700 first.
5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	701
31335 5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	702
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	703 Multiple constructors ~
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	704
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	705 Normally a class has just one new() constructor. In case you find that the
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	706 constructor is often called with the same arguments you may want to simplify
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	707 your code by putting those arguments into a second constructor method. For
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	708 example, if you tend to use the color black a lot: >
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	709
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	710 def new(this.garment, this.color, this.size)
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	711 enddef
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	712 ...
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	713 var pants = new(Garment.pants, Color.black, "XL")
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	714 var shirt = new(Garment.shirt, Color.black, "XL")
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	715 var shoes = new(Garment.shoes, Color.black, "45")
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	716
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	717 Instead of repeating the color every time you can add a constructor that
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	718 includes it: >
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	719
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	720 def newBlack(this.garment, this.size)
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	721 this.color = Color.black
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	722 enddef
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	723 ...
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	724 var pants = newBlack(Garment.pants, "XL")
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	725 var shirt = newBlack(Garment.shirt, "XL")
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	726 var shoes = newBlack(Garment.shoes, "9.5")
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	727
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	728 Note that the method name must start with "new". If there is no method called
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	729 "new()" then the default constructor is added, even though there are other
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	730 constructor methods.
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	731
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	732
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	733 ==============================================================================
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	734
31885 cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	735 7. Type definition Vim9-type :type
31335 5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	736
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	737 A type definition is giving a name to a type specification. For Example: >
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	738
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	739 :type ListOfStrings list<string>
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	740
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	741 TODO: more explanation
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	742
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	743
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	744 ==============================================================================
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	745
31885 cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	746 8. Enum Vim9-enum :enum :endenum
31335 5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	747
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	748 An enum is a type that can have one of a list of values. Example: >
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	749
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	750 :enum Color
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	751 White
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	752 Red
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	753 Green
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	754 Blue
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	755 Black
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	756 :endenum
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	757
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	758 TODO: more explanation
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	759
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	760
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	761 ==============================================================================
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	762
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	763 9. Rationale
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	764
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	765 Most of the choices for \|Vim9\| classes come from popular and recently
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	766 developed languages, such as Java, TypeScript and Dart. The syntax has been
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	767 made to fit with the way Vim script works, such as using `endclass` instead of
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	768 using curly braces around the whole class.
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	769
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	770 Some common constructs of object-oriented languages were chosen very long ago
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	771 when this kind of programming was still new, and later found to be
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	772 sub-optimal. By this time those constructs were widely used and changing them
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	773 was not an option. In Vim we do have the freedom to make different choices,
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	774 since classes are completely new. We can make the syntax simpler and more
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	775 consistent than what "old" languages use. Without diverting too much, it
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	776 should still mostly look like what you know from existing languages.
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	777
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	778 Some recently developed languages add all kinds of fancy features that we
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	779 don't need for Vim. But some have nice ideas that we do want to use.
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	780 Thus we end up with a base of what is common in popular languages, dropping
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	781 what looks like a bad idea, and adding some nice features that are easy to
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	782 understand.
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	783
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	784 The main rules we use to make decisions:
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	785 - Keep it simple.
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	786 - No surprises, mostly do what other languages are doing.
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	787 - Avoid mistakes from the past.
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	788 - Avoid the need for the script writer to consult the help to understand how
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	789 things work, most things should be obvious.
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	790 - Keep it consistent.
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	791 - Aim at an average size plugin, not at a huge project.
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	792
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	793
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	794 Using new() for the constructor ~
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	795
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	796 Many languages use the class name for the constructor method. A disadvantage
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	797 is that quite often this is a long name. And when changing the class name all
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	798 constructor methods need to be renamed. Not a big deal, but still a
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	799 disadvantage.
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	800
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	801 Other languages, such as TypeScript, use a specific name, such as
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	802 "constructor()". That seems better. However, using "new" or "new()" to
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	803 create a new object has no obvious relation with "constructor()".
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	804
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	805 For \|Vim9\| script using the same method name for all constructors seemed like
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	806 the right choice, and by calling it new() the relation between the caller and
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	807 the method being called is obvious.
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	808
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	809
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	810 No overloading of the constructor ~
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	811
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	812 In Vim script, both legacy and \|Vim9\| script, there is no overloading of
33351 a3bbd065fb87 runtime(doc): Vim9: Consistenly use class/object variable and class/object method in help (#13149) Christian Brabandt <cb@256bit.org> parents: 33286 diff changeset	813 methods. That means it is not possible to use the same method name with
31335 5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	814 different types of arguments. Therefore there also is only one new()
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	815 constructor.
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	816
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	817 With \|Vim9\| script it would be possible to support overloading, since
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	818 arguments are typed. However, this gets complicated very quickly. Looking at
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	819 a new() call one has to inspect the types of the arguments to know which of
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	820 several new() methods is actually being called. And that can require
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	821 inspecting quite a bit of code. For example, if one of the arguments is the
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	822 return value of a method, you need to find that method to see what type it is
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	823 returning.
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	824
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	825 Instead, every constructor has to have a different name, starting with "new".
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	826 That way multiple constructors with different arguments are possible, while it
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	827 is very easy to see which constructor is being used. And the type of
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	828 arguments can be properly checked.
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	829
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	830
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	831 No overloading of methods ~
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	832
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	833 Same reasoning as for the constructor: It is often not obvious what type
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	834 arguments have, which would make it difficult to figure out what method is
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	835 actually being called. Better just give the methods a different name, then
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	836 type checking will make sure it works as you intended. This rules out
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	837 polymorphism, which we don't really need anyway.
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	838
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	839
31671 5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	840 Single inheritance and interfaces ~
5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	841
5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	842 Some languages support multiple inheritance. Although that can be useful in
5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	843 some cases, it makes the rules of how a class works quite complicated.
5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	844 Instead, using interfaces to declare what is supported is much simpler. The
5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	845 very popular Java language does it this way, and it should be good enough for
31885 cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	846 Vim. The "keep it simple" rule applies here.
31671 5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	847
5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	848 Explicitly declaring that a class supports an interface makes it easy to see
5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	849 what a class is intended for. It also makes it possible to do proper type
5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	850 checking. When an interface is changed any class that declares to implement
5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	851 it will be checked if that change was also changed. The mechanism to assume a
5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	852 class implements an interface just because the methods happen to match is
5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	853 brittle and leads to obscure problems, let's not do that.
5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	854
5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	855
33351 a3bbd065fb87 runtime(doc): Vim9: Consistenly use class/object variable and class/object method in help (#13149) Christian Brabandt <cb@256bit.org> parents: 33286 diff changeset	856 Using "this.variable" everywhere ~
31335 5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	857
33351 a3bbd065fb87 runtime(doc): Vim9: Consistenly use class/object variable and class/object method in help (#13149) Christian Brabandt <cb@256bit.org> parents: 33286 diff changeset	858 The object variables in various programming languages can often be accessed in
31335 5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	859 different ways, depending on the location. Sometimes "this." has to be
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	860 prepended to avoid ambiguity. They are usually declared without "this.".
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	861 That is quite inconsistent and sometimes confusing.
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	862
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	863 A very common issue is that in the constructor the arguments use the same name
33351 a3bbd065fb87 runtime(doc): Vim9: Consistenly use class/object variable and class/object method in help (#13149) Christian Brabandt <cb@256bit.org> parents: 33286 diff changeset	864 as the object variable. Then for these variables "this." needs to be prefixed
a3bbd065fb87 runtime(doc): Vim9: Consistenly use class/object variable and class/object method in help (#13149) Christian Brabandt <cb@256bit.org> parents: 33286 diff changeset	865 in the body, while for other variables this is not needed and often omitted.
a3bbd065fb87 runtime(doc): Vim9: Consistenly use class/object variable and class/object method in help (#13149) Christian Brabandt <cb@256bit.org> parents: 33286 diff changeset	866 This leads to a mix of variables with and without "this.", which is
a3bbd065fb87 runtime(doc): Vim9: Consistenly use class/object variable and class/object method in help (#13149) Christian Brabandt <cb@256bit.org> parents: 33286 diff changeset	867 inconsistent.
31335 5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	868
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	869 For \|Vim9\| classes the "this." prefix is always used. Also for declaring the
33351 a3bbd065fb87 runtime(doc): Vim9: Consistenly use class/object variable and class/object method in help (#13149) Christian Brabandt <cb@256bit.org> parents: 33286 diff changeset	870 variables. Simple and consistent. When looking at the code inside a class
a3bbd065fb87 runtime(doc): Vim9: Consistenly use class/object variable and class/object method in help (#13149) Christian Brabandt <cb@256bit.org> parents: 33286 diff changeset	871 it's also directly clear which variable references are object variables and
a3bbd065fb87 runtime(doc): Vim9: Consistenly use class/object variable and class/object method in help (#13149) Christian Brabandt <cb@256bit.org> parents: 33286 diff changeset	872 which aren't.
31335 5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	873
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	874
33351 a3bbd065fb87 runtime(doc): Vim9: Consistenly use class/object variable and class/object method in help (#13149) Christian Brabandt <cb@256bit.org> parents: 33286 diff changeset	875 Using class variables ~
31335 5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	876
33351 a3bbd065fb87 runtime(doc): Vim9: Consistenly use class/object variable and class/object method in help (#13149) Christian Brabandt <cb@256bit.org> parents: 33286 diff changeset	877 Using "static variable" to declare a class variable is very common, nothing
a3bbd065fb87 runtime(doc): Vim9: Consistenly use class/object variable and class/object method in help (#13149) Christian Brabandt <cb@256bit.org> parents: 33286 diff changeset	878 new here. In \|Vim9\| script these can be accessed directly by their name.
a3bbd065fb87 runtime(doc): Vim9: Consistenly use class/object variable and class/object method in help (#13149) Christian Brabandt <cb@256bit.org> parents: 33286 diff changeset	879 Very much like how a script-local variable can be used in a method. Since
a3bbd065fb87 runtime(doc): Vim9: Consistenly use class/object variable and class/object method in help (#13149) Christian Brabandt <cb@256bit.org> parents: 33286 diff changeset	880 object variables are always accessed with "this." prepended, it's also quickly
a3bbd065fb87 runtime(doc): Vim9: Consistenly use class/object variable and class/object method in help (#13149) Christian Brabandt <cb@256bit.org> parents: 33286 diff changeset	881 clear what kind of variable it is.
31335 5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	882
33351 a3bbd065fb87 runtime(doc): Vim9: Consistenly use class/object variable and class/object method in help (#13149) Christian Brabandt <cb@256bit.org> parents: 33286 diff changeset	883 TypeScript prepends the class name before the class variable name, also inside
a3bbd065fb87 runtime(doc): Vim9: Consistenly use class/object variable and class/object method in help (#13149) Christian Brabandt <cb@256bit.org> parents: 33286 diff changeset	884 the class. This has two problems: The class name can be rather long, taking
a3bbd065fb87 runtime(doc): Vim9: Consistenly use class/object variable and class/object method in help (#13149) Christian Brabandt <cb@256bit.org> parents: 33286 diff changeset	885 up quite a bit of space, and when the class is renamed all these places need
a3bbd065fb87 runtime(doc): Vim9: Consistenly use class/object variable and class/object method in help (#13149) Christian Brabandt <cb@256bit.org> parents: 33286 diff changeset	886 to be changed too.
31335 5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	887
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	888
33351 a3bbd065fb87 runtime(doc): Vim9: Consistenly use class/object variable and class/object method in help (#13149) Christian Brabandt <cb@256bit.org> parents: 33286 diff changeset	889 Declaring object and class variables ~
31671 5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	890
5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	891 The main choice is whether to use "var" as with variable declarations.
5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	892 TypeScript does not use it: >
5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	893 class Point {
5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	894 x: number;
5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	895 y = 0;
5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	896 }
5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	897
33351 a3bbd065fb87 runtime(doc): Vim9: Consistenly use class/object variable and class/object method in help (#13149) Christian Brabandt <cb@256bit.org> parents: 33286 diff changeset	898 Following that Vim object variables could be declared like this: >
31671 5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	899 class Point
5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	900 this.x: number
5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	901 this.y = 0
5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	902 endclass
5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	903
5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	904 Some users pointed out that this looks more like an assignment than a
5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	905 declaration. Adding "var" changes that: >
5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	906 class Point
5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	907 var this.x: number
5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	908 var this.y = 0
5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	909 endclass
5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	910
33351 a3bbd065fb87 runtime(doc): Vim9: Consistenly use class/object variable and class/object method in help (#13149) Christian Brabandt <cb@256bit.org> parents: 33286 diff changeset	911 We also need to be able to declare class variables using the "static" keyword.
31671 5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	912 There we can also choose to leave out "var": >
5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	913 class Point
5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	914 var this.x: number
5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	915 static count = 0
5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	916 endclass
5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	917
5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	918 Or do use it, before "static": >
5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	919 class Point
5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	920 var this.x: number
5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	921 var static count = 0
5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	922 endclass
5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	923
5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	924 Or after "static": >
5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	925 class Point
5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	926 var this.x: number
5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	927 static var count = 0
5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	928 endclass
5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	929
5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	930 This is more in line with "static def Func()".
5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	931
5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	932 There is no clear preference whether to use "var" or not. The two main
5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	933 reasons to leave it out are:
5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	934 1. TypeScript, Java and other popular languages do not use it.
5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	935 2. Less clutter.
5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	936
5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	937
31335 5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	938 Using "ClassName.new()" to construct an object ~
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	939
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	940 Many languages use the "new" operator to create an object, which is actually
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	941 kind of strange, since the constructor is defined as a method with arguments,
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	942 not a command. TypeScript also has the "new" keyword, but the method is
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	943 called "constructor()", it is hard to see the relation between the two.
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	944
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	945 In \|Vim9\| script the constructor method is called new(), and it is invoked as
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	946 new(), simple and straightforward. Other languages use "new ClassName()",
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	947 while there is no ClassName() method, it's a method by another name in the
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	948 class called ClassName. Quite confusing.
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	949
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	950
33351 a3bbd065fb87 runtime(doc): Vim9: Consistenly use class/object variable and class/object method in help (#13149) Christian Brabandt <cb@256bit.org> parents: 33286 diff changeset	951 Default read access to object variables ~
31335 5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	952
33351 a3bbd065fb87 runtime(doc): Vim9: Consistenly use class/object variable and class/object method in help (#13149) Christian Brabandt <cb@256bit.org> parents: 33286 diff changeset	953 Some users will remark that the access rules for object variables are
31335 5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	954 asymmetric. Well, that is intentional. Changing a value is a very different
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	955 action than reading a value. The read operation has no side effects, it can
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	956 be done any number of times without affecting the object. Changing the value
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	957 can have many side effects, and even have a ripple effect, affecting other
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	958 objects.
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	959
33351 a3bbd065fb87 runtime(doc): Vim9: Consistenly use class/object variable and class/object method in help (#13149) Christian Brabandt <cb@256bit.org> parents: 33286 diff changeset	960 When adding object variables one usually doesn't think much about this, just
a3bbd065fb87 runtime(doc): Vim9: Consistenly use class/object variable and class/object method in help (#13149) Christian Brabandt <cb@256bit.org> parents: 33286 diff changeset	961 get the type right. And normally the values are set in the new() method.
31335 5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	962 Therefore defaulting to read access only "just works" in most cases. And when
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	963 directly writing you get an error, which makes you wonder if you actually want
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	964 to allow that. This helps writing code with fewer mistakes.
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	965
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	966
33351 a3bbd065fb87 runtime(doc): Vim9: Consistenly use class/object variable and class/object method in help (#13149) Christian Brabandt <cb@256bit.org> parents: 33286 diff changeset	967 Making object variables private with an underscore ~
31335 5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	968
33351 a3bbd065fb87 runtime(doc): Vim9: Consistenly use class/object variable and class/object method in help (#13149) Christian Brabandt <cb@256bit.org> parents: 33286 diff changeset	969 When an object variable is private, it can only be read and changed inside the
31335 5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	970 class (and in sub-classes), then it cannot be used outside of the class.
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	971 Prepending an underscore is a simple way to make that visible. Various
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	972 programming languages have this as a recommendation.
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	973
33351 a3bbd065fb87 runtime(doc): Vim9: Consistenly use class/object variable and class/object method in help (#13149) Christian Brabandt <cb@256bit.org> parents: 33286 diff changeset	974 In case you change your mind and want to make the object variable accessible
31335 5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	975 outside of the class, you will have to remove the underscore everywhere.
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	976 Since the name only appears in the class (and sub-classes) they will be easy
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	977 to find and change.
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	978
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	979 The other way around is much harder: you can easily prepend an underscore to
33351 a3bbd065fb87 runtime(doc): Vim9: Consistenly use class/object variable and class/object method in help (#13149) Christian Brabandt <cb@256bit.org> parents: 33286 diff changeset	980 the object variable inside the class to make it private, but any usage
a3bbd065fb87 runtime(doc): Vim9: Consistenly use class/object variable and class/object method in help (#13149) Christian Brabandt <cb@256bit.org> parents: 33286 diff changeset	981 elsewhere you will have to track down and change. You may have to make it a
a3bbd065fb87 runtime(doc): Vim9: Consistenly use class/object variable and class/object method in help (#13149) Christian Brabandt <cb@256bit.org> parents: 33286 diff changeset	982 "set" method call. This reflects the real world problem that taking away
a3bbd065fb87 runtime(doc): Vim9: Consistenly use class/object variable and class/object method in help (#13149) Christian Brabandt <cb@256bit.org> parents: 33286 diff changeset	983 access requires work to be done for all places where that access exists.
31335 5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	984
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	985 An alternative would have been using the "private" keyword, just like "public"
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	986 changes the access in the other direction. Well, that's just to reduce the
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	987 number of keywords.
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	988
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	989
33351 a3bbd065fb87 runtime(doc): Vim9: Consistenly use class/object variable and class/object method in help (#13149) Christian Brabandt <cb@256bit.org> parents: 33286 diff changeset	990 No protected object variables ~
31335 5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	991
33351 a3bbd065fb87 runtime(doc): Vim9: Consistenly use class/object variable and class/object method in help (#13149) Christian Brabandt <cb@256bit.org> parents: 33286 diff changeset	992 Some languages provide several ways to control access to object variables.
a3bbd065fb87 runtime(doc): Vim9: Consistenly use class/object variable and class/object method in help (#13149) Christian Brabandt <cb@256bit.org> parents: 33286 diff changeset	993 The most known is "protected", and the meaning varies from language to
a3bbd065fb87 runtime(doc): Vim9: Consistenly use class/object variable and class/object method in help (#13149) Christian Brabandt <cb@256bit.org> parents: 33286 diff changeset	994 language. Others are "shared", "private" and even "friend".
31335 5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	995
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	996 These rules make life more difficult. That can be justified in projects where
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	997 many people work on the same, complex code where it is easy to make mistakes.
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	998 Especially when refactoring or other changes to the class model.
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	999
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	1000 The Vim scripts are expected to be used in a plugin, with just one person or a
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	1001 small team working on it. Complex rules then only make it more complicated,
32294 b2e8663e6dcc Update runtime files Bram Moolenaar <Bram@vim.org> parents: 32061 diff changeset	1002 the extra safety provided by the rules isn't really needed. Let's just keep
b2e8663e6dcc Update runtime files Bram Moolenaar <Bram@vim.org> parents: 32061 diff changeset	1003 it simple and not specify access details.
31335 5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	1004
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	1005
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	1006 ==============================================================================
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	1007
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	1008 10. To be done later
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	1009
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	1010 Can a newSomething() constructor invoke another constructor? If yes, what are
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	1011 the restrictions?
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	1012
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	1013 Thoughts:
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	1014 - Generics for a class: `class <Tkey, Tentry>`
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	1015 - Generics for a function: `def <Tkey> GetLast(key: Tkey)`
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	1016 - Mixins: not sure if that is useful, leave out for simplicity.
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	1017
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	1018 Some things that look like good additions:
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	1019 - For testing: Mock mechanism
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	1020
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	1021 An important class to be provided is "Promise". Since Vim is single
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	1022 threaded, connecting asynchronous operations is a natural way of allowing
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	1023 plugins to do their work without blocking the user. It's a uniform way to
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	1024 invoke callbacks and handle timeouts and errors.
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	1025
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	1026
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	1027 vim:tw=78:ts=8:noet:ft=help:norl:

Mercurial > vim

annotate runtime/doc/vim9class.txt @ 33385:b5ad84fdc702 v9.0.1951