vim: runtime/doc/vim9class.txt annotate

annotate runtime/doc/vim9class.txt @ 31441:e572ff386670 v9.0.1053

patch 9.0.1053: default constructor arguments are not optional Commit: https://github.com/vim/vim/commit/65b0d1676814ee08fb58ef8d64dd342d1d883192 Author: Bram Moolenaar <Bram@vim.org> Date: Tue Dec 13 18:43:22 2022 +0000 patch 9.0.1053: default constructor arguments are not optional Problem: Default constructor arguments are not optional. Solution: Use "= v:none" to make constructor arguments optional.

author	Bram Moolenaar <Bram@vim.org>
date	Tue, 13 Dec 2022 19:45:04 +0100
parents	e5e95e8c78a7
children	7d68a90cbf5c

rev	line source
31430 e5e95e8c78a7 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31396 diff changeset	1 vim9class.txt For Vim version 9.0. Last change: 2022 Dec 11
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
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	7 NOTE - This is under development, anything can still change! - NOTE
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\|
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	14 3. Using an abstract class \|Vim9-abstract-class\|
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	15 4. Using an interface \|Vim9-using-interface\|
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	16 5. More class details \|Vim9-class\|
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	17 6. Type definition \|Vim9-type\|
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	18 7. Enum \|Vim9-enum\|
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	19
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	20 9. Rationale
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	21 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	22
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 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	26
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	27 The fancy term is "object-oriented programming". You can find lots of study
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	28 material about this subject. Here we document what \|Vim9\| script provides,
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	29 assuming you know the basics already. Added are helpful hints about how
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	30 to use this functionality effectively.
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	31
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	32 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	33 - 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	34 have a value.
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	35 - An object usually provides functions that manipulate its state. These
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	36 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	37 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	38 - 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	39 member functions.
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	40 - Objects are created by a class and all objects have the same interface.
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	41 This never changes, it is not dynamic.
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	42
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	43 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	44 - 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	45 This method is invoked on the class name: MyClass.new().
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	46 - State shared by all objects of the class: class variables and constants.
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	47 - 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	48
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	49 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	50 - 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	51 - 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	52
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	53 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	54 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	55
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 Class modeling ~
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	58
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	59 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	60 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	61 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	62 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	63 should match your purpose.
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	64
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	65 You will soon find that composition is often better than inheritance. Don't
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	66 waste time trying to find the optimal class model. Or waste time discussing
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	67 whether a square is a rectangle or that a rectangle is a square. It doesn't
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	68 matter.
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	69
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 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	74
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	75 Let's start with a simple example: a class that stores a text position: >
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	76
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	77 class TextPosition
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	78 this.lnum: number
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	79 this.col: number
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	80
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	81 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	82 this.lnum = lnum
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	83 this.col = col
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	84 enddef
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	85
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	86 def SetLnum(lnum: number)
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	87 this.lnum = lnum
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	88 enddef
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	89
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	90 def SetCol(col: number)
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	91 this.col = col
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	92 enddef
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	93
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	94 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	95 this.lnum = lnum
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	96 this.col = col
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	97 enddef
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	98 endclass
31430 e5e95e8c78a7 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31396 diff changeset	99 < object Object
31335 5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	100 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	101
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	102 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	103
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	104 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	105
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	106 echo $'The text position is ({pos.lnum}, {pos.col})'
31430 e5e95e8c78a7 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31396 diff changeset	107 < E1317 E1327
31335 5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	108 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	109 in Vim the object members are consistently referred to with the "this."
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	110 prefix. This is different from languages like Java and TypeScript. This
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	111 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	112 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	113
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	114
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	115 Member write access ~
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 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	118
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	119 pos.lnum = 9
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 This will give you an error! That is because by default object members can be
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	122 read but not set. That's why the class provides a method for it: >
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	123
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	124 pos.SetLnum(9)
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 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	127 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	128 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	129 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	130 the closest valid value.
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	131
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	132 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	133 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	134
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	135 public this.lnum: number
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	136 public this.col number
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	137
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	138 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	139 "pos.lnum" directly above will no longer give an error.
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	140
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	141
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	142 Private members ~
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	143
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	144 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	145 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	146 name: >
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 this._lnum: number
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	149 this._col number
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	150
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	151 Now you need to provide methods to get the value of the private members.
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	152 These are commonly call getters. We recommend using a name that starts with
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	153 "Get": >
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	154
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	155 def GetLnum(): number
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	156 return this._lnum
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	157 enddef
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	158
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	159 def GetCol() number
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	160 return this._col
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	161 enddef
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	162
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	163 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	164 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	165 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	166
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	167 def GetLnum(): number
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	168 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	169 return this._lineCount
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	170 endif
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	171 return this._lnum
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	172 enddef
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	173
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	174
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	175 Simplifying the new() method ~
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	176
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	177 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	178 this pattern: >
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 this.lnum: number
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	181 this.col: number
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 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	184 this.lnum = lnum
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	185 this.col = col
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	186 enddef
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	187
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	188 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	189 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	190
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	191 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	192 enddef
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	193
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	194 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	195 including "this.", as the argument to new() means the value provided in the
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	196 new() call is assigned to that object member. This mechanism is coming from
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	197 the Dart language.
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 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	200 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	201 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	202 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	203 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	204 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	205 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	206
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	207 TODO: for a sub-class the constructor of the parent class will be invoked
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	208 somewhere.
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	209
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	210
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	211 ==============================================================================
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	212
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	213 3. Using an abstract class Vim9-abstract-class
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	214
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	215 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	216 model one often finds that a few classes have the same properties that can be
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	217 shared, but a class with those properties does not have enough state to create
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	218 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	219 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	220
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	221 An abstract class does not have a new() method.
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 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	224 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	225 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	226 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	227
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	228 abstract class Shape
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	229 this.color = Color.Black
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	230 this.thickness = 10
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	231 endclass
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	232
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	233 class Square extends Shape
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	234 this.size: number
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 def new(this.size)
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	237 enddef
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	238 endclass
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	239
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	240 class Triangle extends Shape
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	241 this.base: number
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	242 this.height: number
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	243
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	244 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	245 enddef
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	246 endclass
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	247 <
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	248 class-member :static
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	249 Class members are declared with "static". They are used by the name without a
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	250 prefix: >
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	251
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	252 class OtherThing
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	253 this.size: number
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	254 static totalSize: number
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	255
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	256 def new(this.size)
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	257 totalSize += this.size
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	258 enddef
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	259 endclass
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	260 <
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	261 class-method
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	262 Class methods are also declared with "static". They have no access to object
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	263 members, they cannot use the "this" keyword. >
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	264
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	265 class OtherThing
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	266 this.size: number
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	267 static totalSize: number
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	268
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	269 " Clear the total size and return the value it had before.
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	270 static def ClearTotalSize(): number
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	271 var prev = totalSize
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	272 totalSize = 0
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	273 return prev
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	274 enddef
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	275 endclass
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	276
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	277
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	278 ==============================================================================
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	279
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	280 4. Using an interface Vim9-using-interface
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	281
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	282 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	283 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	284 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	285 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	286
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	287 abstract class Shape
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	288 this.color = Color.Black
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	289 this.thickness = 10
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	290 endclass
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	291
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	292 interface HasSurface
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	293 def Surface(): number
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	294 endinterface
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	295
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	296 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	297 this.size: number
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 def new(this.size)
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	300 enddef
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	301
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	302 def Surface(): number
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	303 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	304 enddef
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	305 endclass
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 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	308 this.base: number
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	309 this.height: number
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 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	312 enddef
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	313
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	314 def Surface(): number
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	315 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	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
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	319 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	320
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	321 var shapes: list<HasSurface> = [
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	322 Square.new(12),
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	323 Triangle.new(8, 15),
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	324 ]
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	325 for shape in shapes
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	326 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	327 endfor
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	328
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	329
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	330 ==============================================================================
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	331
31430 e5e95e8c78a7 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31396 diff changeset	332 5. 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	333
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	334 Defining a class ~
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	335 :class :endclass :abstract
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	336 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	337 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	338
31430 e5e95e8c78a7 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31396 diff changeset	339 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	340 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	341
31335 5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	342 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	343 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	344 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	345
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	346 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	347 these variants: >
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	348
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	349 class ClassName
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 export class ClassName
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	353 endclass
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	354
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	355 abstract class ClassName
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	356 endclass
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	357
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	358 export abstract class ClassName
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	359 endclass
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	360 <
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	361 E1314
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	362 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	363 That avoids clashing with builtin types.
31430 e5e95e8c78a7 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31396 diff changeset	364 E1315
31335 5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	365 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	366 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	367 extends ClassName
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	368 implements InterfaceName, OtherInterface
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	369 specifies SomeInterface
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	370 < extends
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	371 A class can extend one other class.
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	372 implements
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	373 A class can implement one or more interfaces.
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	374 specifies
31396 307f68a41b03 patch 9.0.1031: Vim9 class is not implemented yet Bram Moolenaar <Bram@vim.org> parents: 31335 diff changeset	375 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	376 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	377 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	378
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	379
31430 e5e95e8c78a7 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31396 diff changeset	380 Items in a class ~
e5e95e8c78a7 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31396 diff changeset	381 E1318 E1325 E1326
e5e95e8c78a7 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31396 diff changeset	382 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	383 - An object member declaration: >
e5e95e8c78a7 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31396 diff changeset	384 this._memberName: memberType
e5e95e8c78a7 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31396 diff changeset	385 this.memberName: memberType
e5e95e8c78a7 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31396 diff changeset	386 public this.memberName: memberType
e5e95e8c78a7 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31396 diff changeset	387 - A constructor method: >
e5e95e8c78a7 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31396 diff changeset	388 def new(arguments)
e5e95e8c78a7 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31396 diff changeset	389 def newName(arguments)
e5e95e8c78a7 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31396 diff changeset	390 - An object method: >
e5e95e8c78a7 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31396 diff changeset	391 def SomeMethod(arguments)
e5e95e8c78a7 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31396 diff changeset	392
e5e95e8c78a7 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31396 diff changeset	393
31335 5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	394 Defining an interface ~
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	395 :interface :endinterface
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	396 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	397 prefixed with `:export`: >
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	398
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	399 interface InterfaceName
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	400 endinterface
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	401
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	402 export interface InterfaceName
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	403 endinterface
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	404
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	405 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	406 initializer.
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	407
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	408 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	409 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	410
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	411 interface HasSurface
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	412 this.size: number
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	413 def Surface(): number
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	414 endinterface
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	415
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	416 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	417 name, with a hint about what it provides.
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	418
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	419
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	420 Default constructor ~
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	421
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	422 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	423 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	424 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	425
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	426 class AutoNew
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	427 this.name: string
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	428 this.age: number
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	429 this.gender: Gender
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	430 endclass
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	431
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	432 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	433
31441 e572ff386670 patch 9.0.1053: default constructor arguments are not optional Bram Moolenaar <Bram@vim.org> parents: 31430 diff changeset	434 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	435 enddef
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	436
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	437 All object members will be used, also private access ones.
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	438
31441 e572ff386670 patch 9.0.1053: default constructor arguments are not optional Bram Moolenaar <Bram@vim.org> parents: 31430 diff changeset	439 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	440 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	441 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	442 with default values: >
31430 e5e95e8c78a7 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31396 diff changeset	443
e5e95e8c78a7 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31396 diff changeset	444 class TextPosition
e5e95e8c78a7 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31396 diff changeset	445 this.lnum: number = 1
e5e95e8c78a7 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31396 diff changeset	446 this.col: number = 1
e5e95e8c78a7 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31396 diff changeset	447 endclass
e5e95e8c78a7 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31396 diff changeset	448
e5e95e8c78a7 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31396 diff changeset	449 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	450 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	451 the name, you can define the constructor like this: >
e5e95e8c78a7 Update runtime files Bram Moolenaar <Bram@vim.org> parents: 31396 diff changeset	452
31441 e572ff386670 patch 9.0.1053: default constructor arguments are not optional Bram Moolenaar <Bram@vim.org> parents: 31430 diff changeset	453 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	454 enddef
31441 e572ff386670 patch 9.0.1053: default constructor arguments are not optional Bram Moolenaar <Bram@vim.org> parents: 31430 diff changeset	455 < E1328
e572ff386670 patch 9.0.1053: default constructor arguments are not optional Bram Moolenaar <Bram@vim.org> parents: 31430 diff changeset	456 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	457 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	458 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	459
31335 5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	460
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	461 Multiple constructors ~
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	462
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	463 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	464 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	465 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	466 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	467
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	468 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	469 enddef
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	470 ...
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	471 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	472 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	473 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	474
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	475 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	476 includes it: >
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	477
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	478 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	479 this.color = Color.black
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	480 enddef
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	481 ...
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	482 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	483 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	484 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	485
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	486 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	487 "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	488 constructor methods.
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	489
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	490
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	491 ==============================================================================
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	492
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	493 6. Type definition Vim9-type :type
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	494
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	495 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	496
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	497 :type ListOfStrings list<string>
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	498
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	499 TODO: more explanation
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	500
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	501
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
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	504 7. Enum Vim9-enum :enum :endenum
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	505
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	506 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	507
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	508 :enum Color
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	509 White
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	510 Red
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	511 Green
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	512 Blue
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	513 Black
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	514 :endenum
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	515
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	516 TODO: more explanation
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	517
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	518
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	519 ==============================================================================
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	520
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	521 9. Rationale
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	522
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	523 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	524 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	525 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	526 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	527
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	528 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	529 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	530 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	531 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	532 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	533 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	534 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	535
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	536 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	537 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	538 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	539 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	540 understand.
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	541
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	542 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	543 - Keep it simple.
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	544 - 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	545 - 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	546 - 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	547 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	548 - Keep it consistent.
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	549 - 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	550
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	551
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	552 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	553
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	554 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	555 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	556 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	557 disadvantage.
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	558
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	559 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	560 "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	561 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	562
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	563 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	564 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	565 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	566
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	567
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	568 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	569
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	570 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	571 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	572 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	573 constructor.
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	574
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	575 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	576 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	577 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	578 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	579 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	580 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	581 returning.
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	582
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	583 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	584 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	585 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	586 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	587
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	588
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	589 No overloading of methods ~
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 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	592 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	593 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	594 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	595 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	596
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 Using "this.member" everywhere ~
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	599
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	600 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	601 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	602 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	603 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	604
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	605 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	606 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	607 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	608 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	609
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	610 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	611 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	612 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	613 aren't.
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
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	616 Single inheritance and interfaces ~
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 Some languages support multiple inheritance. Although that can be useful in
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	619 some cases, it makes the rules of how a class works quite complicated.
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	620 Instead, using interfaces to declare what is supported is much simpler. The
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	621 very popular Java language does it this way, and it should be good enough for
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	622 Vim. The "keep it simple" rule applies here.
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 Explicitly declaring that a class supports an interface makes it easy to see
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	625 what a class is intended for. It also makes it possible to do proper type
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	626 checking. When an interface is changed any class that declares to implement
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	627 it will be checked if that change was also changed. The mechanism to assume a
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	628 class implements an interface just because the methods happen to match is
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	629 brittle and leads to obscure problems, let's not do that.
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	630
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 Using class members ~
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 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	635 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	636 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	637 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	638 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	639
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	640 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	641 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	642 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	643 be changed too.
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	644
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	645
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	646 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	647
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	648 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	649 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	650 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	651 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	652
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	653 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	654 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	655 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	656 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	657
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	658
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	659 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	660
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	661 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	662 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	663 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	664 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	665 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	666 objects.
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 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	669 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	670 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	671 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	672 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	673
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	674
31396 307f68a41b03 patch 9.0.1031: Vim9 class is not implemented yet Bram Moolenaar <Bram@vim.org> parents: 31335 diff changeset	675 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	676
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	677 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	678 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	679 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	680 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	681
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	682 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	683 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	684 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	685 to find and change.
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	686
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	687 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	688 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	689 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	690 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	691 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	692
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	693 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	694 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	695 number of keywords.
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	696
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	697
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	698 No protected object members ~
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	699
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	700 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	701 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	702 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	703
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	704 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	705 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	706 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	707
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	708 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	709 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	710 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	711 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	712
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	713
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	714 ==============================================================================
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	715
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	716 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	717
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	718 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	719 the restrictions?
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	720
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	721 Thoughts:
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	722 - 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	723 - 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	724 - 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	725
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	726 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	727 - For testing: Mock mechanism
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	728
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	729 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	730 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	731 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	732 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	733
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	734
5acc0d2cf4f7 patch 9.0.1001: classes are not documented or implemented yet Bram Moolenaar <Bram@vim.org> parents: diff changeset	735 vim:tw=78:ts=8:noet:ft=help:norl:

Mercurial > vim

annotate runtime/doc/vim9class.txt @ 31441:e572ff386670 v9.0.1053