vim: runtime/doc/vim9class.txt annotate

annotate runtime/doc/vim9class.txt @ 32004:a9b5ffbc0428

Update runtime files. Commit: https://github.com/vim/vim/commit/938ae280c79b8cdb0fca60336ec4c090ecd8bb5a Author: Bram Moolenaar <Bram@vim.org> Date: Mon Feb 20 20:44:55 2023 +0000 Update runtime files.

author	Bram Moolenaar <Bram@vim.org>
date	Mon, 20 Feb 2023 22:00:05 +0100
parents	cc751d944b7e
children	b2412874362f

rev	line source
32004 a9b5ffbc0428 Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31885 diff changeset	1 vim9class.txt For Vim version 9.0. Last change: 2023 Feb 19
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\|
31885 cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	14 3. Class members and functions \|Vim9-class-member\|
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
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	40 member functions.
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
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	106 The object members "lnum" and "col" can be accessed directly: >
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
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	114 variable does not have the "this." prefix you know it is not an object member.
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	115
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 Member write access ~
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	118
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	119 Now try to change an object member directly: >
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	120
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	121 pos.lnum = 9
31885 cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	122 < E1335
31335 5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	123 This will give you an error! That is because by default object members can be
31885 cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	124 read but not set. That's why the TextPosition class provides a method for it: >
31335 5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	125
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	126 pos.SetLnum(9)
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 Allowing to read but not set an object member is the most common and safest
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	129 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	130 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	131 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	132 the closest valid value.
31885 cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	133 :public E1331
31335 5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	134 If you don't care about side effects and want to allow the object member to be
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	135 changed at any time, you can make it public: >
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	136
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	137 public this.lnum: number
31885 cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	138 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	139
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	140 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	141 "pos.lnum" directly above will no longer give an error.
31579 7d68a90cbf5c Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31441 diff changeset	142 E1334
7d68a90cbf5c Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31441 diff changeset	143 If you try to set an object member that doesn't exist you get an error: >
7d68a90cbf5c Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31441 diff changeset	144 pos.other = 9
7d68a90cbf5c Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31441 diff changeset	145 < E1334: Object member not found: other ~
31335 5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	146
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	147
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	148 Private members ~
31579 7d68a90cbf5c Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31441 diff changeset	149 E1332 E1333
31335 5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	150 On the other hand, if you do not want the object members to be read directly,
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	151 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	152 name: >
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	153
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	154 this._lnum: number
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	155 this._col number
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	156
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	157 Now you need to provide methods to get the value of the private members.
31885 cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	158 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	159 "Get": >
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	160
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	161 def GetLnum(): number
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	162 return this._lnum
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	163 enddef
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 GetCol() number
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	166 return this._col
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 This example isn't very useful, the members might as well have been public.
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	170 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	171 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	172
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	173 def GetLnum(): number
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	174 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	175 return this._lineCount
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	176 endif
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	177 return this._lnum
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	178 enddef
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	179
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	180
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	181 Simplifying the new() method ~
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	182
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	183 Many constructors take values for the object members. Thus you very often see
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	184 this pattern: >
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	185
31885 cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	186 class SomeClass
31335 5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	187 this.lnum: number
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	188 this.col: number
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	189
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	190 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	191 this.lnum = lnum
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	192 this.col = col
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	193 enddef
31885 cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	194 endclass
31335 5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	195
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	196 Not only is this text you need to write, it also has the type of each member
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	197 twice. Since this is so common a shorter way to write new() is provided: >
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	198
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	199 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	200 enddef
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	201
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	202 The semantics are easy to understand: Providing the object member name,
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	203 including "this.", as the argument to new() means the value provided in the
31885 cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	204 new() call is assigned to that object member. This mechanism comes from the
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	205 Dart language.
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	206
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	207 Putting together this way of using new() and making the members public results
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	208 in a much shorter class definition as what we started with: >
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	209
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	210 class TextPosition
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	211 public this.lnum: number
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	212 public this.col: number
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	213
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	214 def new(this.lnum, this.col)
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	215 enddef
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	216
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	217 def SetPosition(lnum: number, col: number)
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	218 this.lnum = lnum
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	219 this.col = col
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	220 enddef
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	221 endclass
31335 5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	222
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	223 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	224 1. Memory is allocated and cleared. All values are zero/false/empty.
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	225 2. For each declared member that has an initializer, the expression is
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	226 evaluated and assigned to the member. This happens in the sequence the
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	227 members are declared in the class.
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	228 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	229 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	230
31885 cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	231 If the class extends a parent class, the same thing happens. In the second
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	232 step the members of the parent class are done first. There is no need to call
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	233 "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	234
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	235 ==============================================================================
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	236
31885 cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	237 3. class members and functions Vim9-class-member
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	238
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	239 :static E1337 E1338
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	240 Class members are declared with "static". They are used by the name without a
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	241 prefix: >
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 class OtherThing
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	244 this.size: number
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	245 static totalSize: number
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	246
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	247 def new(this.size)
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	248 totalSize += this.size
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	249 enddef
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	250 endclass
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	251 < E1340 E1341
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	252 Since the name is used as-is, shadowing the name by a function argument name
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	253 or local variable name is not allowed.
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	254
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	255 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	256 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	257 "public": >
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	258
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	259 class OtherThing
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	260 static total: number # anybody can read, only class can write
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	261 static _sum: number # only class can read and write
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	262 public static result: number # anybody can read and write
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	263 endclass
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	264 <
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	265 class-function
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	266 Class functions are also declared with "static". They have no access to
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	267 object members, they cannot use the "this" keyword. >
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	268
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	269 class OtherThing
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	270 this.size: number
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	271 static totalSize: number
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	272
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	273 # Clear the total size and return the value it had before.
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	274 static def ClearTotalSize(): number
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	275 var prev = totalSize
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	276 totalSize = 0
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	277 return prev
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	278 enddef
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	279 endclass
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	280
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	281 Inside the class the function can be called by name directly, outside the
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	282 class the class name must be prefixed: `OtherThing.ClearTotalSize()`.
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	283
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	284 ==============================================================================
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	285
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	286 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	287
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	288 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	289 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	290 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	291 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	292 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	293
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	294 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	295 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	296 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	297 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	298
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	299 abstract class Shape
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	300 this.color = Color.Black
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	301 this.thickness = 10
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	302 endclass
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	303
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	304 class Square extends Shape
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	305 this.size: number
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	306
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	307 def new(this.size)
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	308 enddef
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	309 endclass
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	310
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	311 class Triangle extends Shape
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	312 this.base: number
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	313 this.height: number
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	314
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	315 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	316 enddef
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	317 endclass
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	318 <
31885 cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	319 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	320 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	321
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	322
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	323 ==============================================================================
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	324
31885 cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	325 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	326
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	327 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	328 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	329 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	330 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	331
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	332 abstract class Shape
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	333 this.color = Color.Black
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	334 this.thickness = 10
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	335 endclass
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	336
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	337 interface HasSurface
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	338 def Surface(): number
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	339 endinterface
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	340
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	341 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	342 this.size: number
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	343
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	344 def new(this.size)
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	345 enddef
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	346
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	347 def Surface(): number
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	348 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	349 enddef
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	350 endclass
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	351
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	352 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	353 this.base: number
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	354 this.height: number
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	355
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	356 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	357 enddef
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	358
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	359 def Surface(): number
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	360 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	361 enddef
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	362 endclass
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	363
31671 5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	364 If a class declares to implement an interface, all the items specified in the
5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	365 interface must appear in the class, with the same types. E1348 E1349
5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	366
31335 5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	367 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	368
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	369 var shapes: list<HasSurface> = [
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	370 Square.new(12),
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	371 Triangle.new(8, 15),
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	372 ]
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	373 for shape in shapes
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	374 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	375 endfor
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	376
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	377
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	378 ==============================================================================
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	379
31885 cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	380 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	381
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	382 Defining a class ~
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	383 :class :endclass :abstract
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	384 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	385 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	386
31430 e5e95e8c78a7 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31396 diff changeset	387 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	388 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	389
31335 5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	390 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	391 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	392 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	393
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	394 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	395 these variants: >
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 class ClassName
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	398 endclass
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	399
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	400 export class ClassName
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	401 endclass
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	402
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	403 abstract class ClassName
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	404 endclass
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	405
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	406 export abstract class ClassName
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	407 endclass
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	408 <
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	409 E1314
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	410 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	411 That avoids clashing with builtin types.
31430 e5e95e8c78a7 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31396 diff changeset	412 E1315
31335 5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	413 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	414 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	415 extends ClassName
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	416 implements InterfaceName, OtherInterface
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	417 specifies SomeInterface
31885 cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	418 < E1355
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	419 Each member and function name can be used only once. It is not possible to
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	420 define a function with the same name and different type of arguments.
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	421
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	422
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	423 Extending a class ~
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	424 extends
31671 5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	425 A class can extend one other class. E1352 E1353 E1354
31885 cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	426 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	427
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	428 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	429 is called the "child class".
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	430
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	431 Object members from the base class are all taken over by the child class. It
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	432 is not possible to override them (unlike some other languages).
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	433
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	434 E1356 E1357 E1358
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	435 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	436 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	437 base class can be called by prefixing "super.".
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	438
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	439 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	440
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	441 Class functions, including functions starting with "new", can be overruled,
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	442 like with object methods. The function on the base class can be called by
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	443 prefixing the name of the class (for class functions) or "super.".
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	444
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	445 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	446 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	447 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	448 call that method from every constructor().
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	449
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	450 If the base class did not specify a new() function then one was automatically
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	451 created. This function will not be taken over by the child class. The child
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	452 class can define its own new() function, or, if there isn't one, a new()
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	453 function will be added automatically.
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	454
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	455
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	456 A class implementing an interface ~
31671 5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	457 implements E1346 E1347
5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	458 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	459 only appear once E1350 . Multiple interfaces can be specified, separated by
5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	460 commas. Each interface name can appear only once. E1351
31885 cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	461
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	462
cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	463 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	464 specifies
31396 307f68a41b03 patch 9.0.1031: Vim9 class is not implemented yet Bram Moolenaar <Bram@vim.org> parents: 31335 diff changeset	465 A class can declare its interface, the object members 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	466 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	467 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	468
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	469
31430 e5e95e8c78a7 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31396 diff changeset	470 Items in a class ~
e5e95e8c78a7 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31396 diff changeset	471 E1318 E1325 E1326
e5e95e8c78a7 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31396 diff changeset	472 Inside a class, in betweeen `:class` and `:endclass`, these items can appear:
e5e95e8c78a7 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31396 diff changeset	473 - An object member declaration: >
32004 a9b5ffbc0428 Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31885 diff changeset	474 this._memberName: memberType
a9b5ffbc0428 Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31885 diff changeset	475 this.memberName: memberType
31430 e5e95e8c78a7 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31396 diff changeset	476 public this.memberName: memberType
e5e95e8c78a7 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31396 diff changeset	477 - A constructor method: >
32004 a9b5ffbc0428 Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31885 diff changeset	478 def new(arguments)
a9b5ffbc0428 Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31885 diff changeset	479 def newName(arguments)
31430 e5e95e8c78a7 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31396 diff changeset	480 - An object method: >
32004 a9b5ffbc0428 Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31885 diff changeset	481 def SomeMethod(arguments)
31579 7d68a90cbf5c Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31441 diff changeset	482 < E1329
7d68a90cbf5c Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31441 diff changeset	483 For the object member the type must be specified. The best way is to do this
7d68a90cbf5c Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31441 diff changeset	484 explicitly with ": {type}". For simple types you can also use an initializer,
7d68a90cbf5c Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31441 diff changeset	485 such as "= 123", and Vim will see that the type is a number. Avoid doing this
7d68a90cbf5c Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31441 diff changeset	486 for more complex types and when the type will be incomplete. For example: >
7d68a90cbf5c Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31441 diff changeset	487 this.nameList = []
7d68a90cbf5c Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31441 diff changeset	488 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	489 this.nameList: list<string>
7d68a90cbf5c Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31441 diff changeset	490 The initialization isn't needed, the list is empty by default.
7d68a90cbf5c Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31441 diff changeset	491 E1330
7d68a90cbf5c Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31441 diff changeset	492 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	493
e5e95e8c78a7 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31396 diff changeset	494
31335 5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	495 Defining an interface ~
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	496 :interface :endinterface
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	497 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	498 prefixed with `:export`: >
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 interface InterfaceName
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	501 endinterface
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 interface InterfaceName
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	504 endinterface
31671 5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	505 < E1344
31335 5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	506 An interface can declare object members, just like in a class but without any
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	507 initializer.
31671 5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	508 E1345
31335 5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	509 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	510 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	511
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	512 interface HasSurface
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	513 this.size: number
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	514 def Surface(): number
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	515 endinterface
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	516
31671 5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	517 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	518 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	519 name, with a hint about what it provides.
31671 5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	520 An interface can only be defined in a \|Vim9\| script file. E1342
31335 5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	521
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	522
32004 a9b5ffbc0428 Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31885 diff changeset	523 null object ~
a9b5ffbc0428 Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31885 diff changeset	524
a9b5ffbc0428 Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31885 diff changeset	525 When a variable is decleared to have the type of an object, but it is not
a9b5ffbc0428 Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31885 diff changeset	526 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	527 does not know what class was supposed to be used. Vim then cannot check if
a9b5ffbc0428 Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31885 diff changeset	528 a member name is correct and you will get an "Using a null object" error,
a9b5ffbc0428 Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31885 diff changeset	529 even when the member name is invalid. E1360
a9b5ffbc0428 Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31885 diff changeset	530
a9b5ffbc0428 Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31885 diff changeset	531
31335 5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	532 Default constructor ~
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	533
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	534 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	535 defined. This default constructor will have arguments for all the object
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	536 members, in the order they were specified. Thus if your class looks like: >
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	537
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	538 class AutoNew
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	539 this.name: string
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	540 this.age: number
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	541 this.gender: Gender
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	542 endclass
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	543
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	544 Then The default constructor will be: >
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	545
31441 e572ff386670 patch 9.0.1053: default constructor arguments are not optional Bram Moolenaar <Bram@vim.org> parents: 31430 diff changeset	546 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	547 enddef
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	548
31441 e572ff386670 patch 9.0.1053: default constructor arguments are not optional Bram Moolenaar <Bram@vim.org> parents: 31430 diff changeset	549 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	550 call `new()` without any arguments. No assignment will happen and the default
e572ff386670 patch 9.0.1053: default constructor arguments are not optional Bram Moolenaar <Bram@vim.org> parents: 31430 diff changeset	551 value for the object members will be used. This is a more useful example,
e572ff386670 patch 9.0.1053: default constructor arguments are not optional Bram Moolenaar <Bram@vim.org> parents: 31430 diff changeset	552 with default values: >
31430 e5e95e8c78a7 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31396 diff changeset	553
e5e95e8c78a7 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31396 diff changeset	554 class TextPosition
e5e95e8c78a7 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31396 diff changeset	555 this.lnum: number = 1
e5e95e8c78a7 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31396 diff changeset	556 this.col: number = 1
e5e95e8c78a7 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31396 diff changeset	557 endclass
e5e95e8c78a7 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31396 diff changeset	558
e5e95e8c78a7 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31396 diff changeset	559 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	560 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	561 the name, you can define the constructor like this: >
e5e95e8c78a7 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31396 diff changeset	562
31441 e572ff386670 patch 9.0.1053: default constructor arguments are not optional Bram Moolenaar <Bram@vim.org> parents: 31430 diff changeset	563 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	564 enddef
31441 e572ff386670 patch 9.0.1053: default constructor arguments are not optional Bram Moolenaar <Bram@vim.org> parents: 31430 diff changeset	565 < E1328
e572ff386670 patch 9.0.1053: default constructor arguments are not optional Bram Moolenaar <Bram@vim.org> parents: 31430 diff changeset	566 Note that you cannot use another default value than "v:none" here. If you
e572ff386670 patch 9.0.1053: default constructor arguments are not optional Bram Moolenaar <Bram@vim.org> parents: 31430 diff changeset	567 want to initialize the object members, do it where they are declared. This
e572ff386670 patch 9.0.1053: default constructor arguments are not optional Bram Moolenaar <Bram@vim.org> parents: 31430 diff changeset	568 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	569
31671 5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	570 All object members will be used in the default constructor, also private
5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	571 access ones.
5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	572
5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	573 If the class extends another one, the object members of that class will come
5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	574 first.
5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	575
31335 5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	576
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	577 Multiple constructors ~
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	578
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	579 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	580 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	581 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	582 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	583
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	584 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	585 enddef
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	586 ...
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	587 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	588 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	589 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	590
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	591 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	592 includes it: >
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	593
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	594 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	595 this.color = Color.black
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	596 enddef
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	597 ...
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	598 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	599 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	600 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	601
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	602 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	603 "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	604 constructor methods.
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	605
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	606
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	607 ==============================================================================
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	608
31885 cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	609 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	610
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	611 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	612
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	613 :type ListOfStrings list<string>
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	614
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	615 TODO: more explanation
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	616
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	617
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	618 ==============================================================================
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	619
31885 cc751d944b7e Update runtime files. Bram Moolenaar <Bram@vim.org> parents: 31671 diff changeset	620 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	621
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	622 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	623
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	624 :enum Color
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	625 White
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	626 Red
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	627 Green
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	628 Blue
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	629 Black
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	630 :endenum
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	631
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	632 TODO: more explanation
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	633
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	634
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
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	637 9. Rationale
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	638
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	639 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	640 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	641 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	642 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	643
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	644 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	645 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	646 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	647 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	648 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	649 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	650 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	651
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	652 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	653 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	654 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	655 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	656 understand.
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	657
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	658 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	659 - Keep it simple.
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	660 - 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	661 - 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	662 - 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	663 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	664 - Keep it consistent.
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	665 - 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	666
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	667
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	668 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	669
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	670 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	671 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	672 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	673 disadvantage.
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	674
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	675 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	676 "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	677 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	678
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	679 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	680 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	681 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	682
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	683
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	684 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	685
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	686 In Vim script, both legacy and \|Vim9\| script, there is no overloading of
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	687 functions. That means it is not possible to use the same function name with
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	688 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	689 constructor.
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	690
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	691 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	692 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	693 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	694 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	695 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	696 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	697 returning.
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	698
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	699 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	700 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	701 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	702 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	703
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 No overloading of methods ~
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	706
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	707 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	708 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	709 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	710 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	711 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	712
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	713
31671 5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	714 Single inheritance and interfaces ~
5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	715
5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	716 Some languages support multiple inheritance. Although that can be useful in
5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	717 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	718 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	719 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	720 Vim. The "keep it simple" rule applies here.
31671 5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	721
5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	722 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	723 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	724 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	725 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	726 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	727 brittle and leads to obscure problems, let's not do that.
5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	728
5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	729
31335 5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	730 Using "this.member" everywhere ~
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 The object members in various programming languages can often be accessed in
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	733 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	734 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	735 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	736
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	737 A very common issue is that in the constructor the arguments use the same name
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	738 as the object member. Then for these members "this." needs to be prefixed in
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	739 the body, while for other members this is not needed and often omitted. This
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	740 leads to a mix of members with and without "this.", which is inconsistent.
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	741
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	742 For \|Vim9\| classes the "this." prefix is always used. Also for declaring the
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	743 members. Simple and consistent. When looking at the code inside a class it's
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	744 also directly clear which variable references are object members and which
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	745 aren't.
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	746
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 Using class members ~
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 Using "static member" to declare a class member is very common, nothing new
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	751 here. In \|Vim9\| script these can be accessed directly by their name. Very
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	752 much like how a script-local variable can be used in a function. Since object
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	753 members are always accessed with "this." prepended, it's also quickly clear
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	754 what kind of member it is.
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	755
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	756 TypeScript prepends the class name before the class member, also inside the
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	757 class. This has two problems: The class name can be rather long, taking up
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	758 quite a bit of space, and when the class is renamed all these places need to
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	759 be changed too.
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
31671 5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	762 Declaring object and class members ~
5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	763
5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	764 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	765 TypeScript does not use it: >
5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	766 class Point {
5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	767 x: number;
5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	768 y = 0;
5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	769 }
5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	770
5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	771 Following that Vim object members could be declared like this: >
5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	772 class Point
5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	773 this.x: number
5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	774 this.y = 0
5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	775 endclass
5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	776
5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	777 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	778 declaration. Adding "var" changes that: >
5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	779 class Point
5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	780 var this.x: number
5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	781 var this.y = 0
5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	782 endclass
5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	783
5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	784 We also need to be able to declare class members using the "static" keyword.
5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	785 There we can also choose to leave out "var": >
5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	786 class Point
5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	787 var this.x: number
5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	788 static count = 0
5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	789 endclass
5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	790
5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	791 Or do use it, before "static": >
5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	792 class Point
5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	793 var this.x: number
5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	794 var static count = 0
5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	795 endclass
5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	796
5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	797 Or after "static": >
5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	798 class Point
5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	799 var this.x: number
5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	800 static var count = 0
5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	801 endclass
5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	802
5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	803 This is more in line with "static def Func()".
5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	804
5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	805 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	806 reasons to leave it out are:
5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	807 1. TypeScript, Java and other popular languages do not use it.
5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	808 2. Less clutter.
5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	809
5ed19049b1e8 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31579 diff changeset	810
31335 5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	811 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	812
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	813 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	814 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	815 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	816 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	817
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	818 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	819 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	820 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	821 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	822
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	823
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	824 Default read access to object members ~
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	825
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	826 Some users will remark that the access rules for object members are
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	827 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	828 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	829 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	830 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	831 objects.
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 When adding object members one usually doesn't think much about this, just get
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	834 the type right. And normally the values are set in the new() method.
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	835 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	836 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	837 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	838
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	839
31396 307f68a41b03 patch 9.0.1031: Vim9 class is not implemented yet Bram Moolenaar <Bram@vim.org> parents: 31335 diff changeset	840 Making object members 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	841
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	842 When an object member is private, it can only be read and changed inside the
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	843 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	844 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	845 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	846
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	847 In case you change your mind and want to make the object member accessible
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	848 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	849 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	850 to find and change.
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	851
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	852 The other way around is much harder: you can easily prepend an underscore to
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	853 the object member inside the class to make it private, but any usage elsewhere
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	854 you will have to track down and change. You may have to make it a "set"
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	855 method call. This reflects the real world problem that taking away access
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	856 requires work to be done for all places where that access exists.
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	857
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	858 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	859 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	860 number of keywords.
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	861
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 No protected object members ~
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	864
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	865 Some languages provide several ways to control access to object members. The
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	866 most known is "protected", and the meaning varies from language to language.
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	867 Others are "shared", "private" and even "friend".
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 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	870 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	871 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	872
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	873 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	874 small team working on it. Complex rules then only make it more complicated,
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	875 the extra safety provide by the rules isn't really needed. Let's just keep it
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	876 simple and not specify access details.
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	877
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	878
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	879 ==============================================================================
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	880
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	881 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	882
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	883 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	884 the restrictions?
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	885
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	886 Thoughts:
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	887 - 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	888 - 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	889 - 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	890
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	891 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	892 - For testing: Mock mechanism
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	893
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	894 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	895 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	896 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	897 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	898
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	899
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	900 vim:tw=78:ts=8:noet:ft=help:norl:

Mercurial > vim

annotate runtime/doc/vim9class.txt @ 32004:a9b5ffbc0428