Mercurial > vim
annotate runtime/doc/vim9class.txt @ 31671:5ed19049b1e8
Update runtime files
Commit: https://github.com/vim/vim/commit/1b5f03ec9c5551047d5de8d845541dd3201abe7c
Author: Bram Moolenaar <Bram@vim.org>
Date: Mon Jan 9 20:12:45 2023 +0000
Update runtime files
author | Bram Moolenaar <Bram@vim.org> |
---|---|
date | Mon, 09 Jan 2023 21:15:05 +0100 |
parents | 7d68a90cbf5c |
children | cc751d944b7e |
rev | line source |
---|---|
31671 | 1 *vim9class.txt* For Vim version 9.0. Last change: 2023 Jan 09 |
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 | 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 | 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 |
31579 | 120 < *E1335* |
31335
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. |
31579 | 131 *:public* *E1331* |
31335
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. |
31579 | 140 *E1334* |
141 If you try to set an object member that doesn't exist you get an error: > | |
142 pos.other = 9 | |
143 < E1334: Object member not found: other ~ | |
31335
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
144 |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
145 |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
146 Private members ~ |
31579 | 147 *E1332* *E1333* |
31335
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
148 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
|
149 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
|
150 name: > |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
151 |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
152 this._lnum: number |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
153 this._col number |
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 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
|
156 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
|
157 "Get": > |
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 GetLnum(): number |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
160 return this._lnum |
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 def GetCol() number |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
164 return this._col |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
165 enddef |
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 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
|
168 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
|
169 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
|
170 |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
171 def GetLnum(): number |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
172 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
|
173 return this._lineCount |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
174 endif |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
175 return this._lnum |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
176 enddef |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
177 |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
178 |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
179 Simplifying the new() method ~ |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
180 |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
181 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
|
182 this pattern: > |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
183 |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
184 this.lnum: number |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
185 this.col: number |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
186 |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
187 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
|
188 this.lnum = lnum |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
189 this.col = col |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
190 enddef |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
191 |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
192 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
|
193 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
|
194 |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
195 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
|
196 enddef |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
197 |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
198 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
|
199 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
|
200 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
|
201 the Dart language. |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
202 |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
203 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
|
204 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
|
205 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
|
206 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
|
207 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
|
208 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
|
209 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
|
210 |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
211 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
|
212 somewhere. |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
213 |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
214 |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
215 ============================================================================== |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
216 |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
217 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
|
218 |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
219 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
|
220 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
|
221 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
|
222 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
|
223 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
|
224 |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
225 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
|
226 |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
227 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
|
228 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
|
229 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
|
230 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
|
231 |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
232 abstract class Shape |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
233 this.color = Color.Black |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
234 this.thickness = 10 |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
235 endclass |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
236 |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
237 class Square extends Shape |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
238 this.size: number |
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 def new(this.size) |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
241 enddef |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
242 endclass |
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 class Triangle extends Shape |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
245 this.base: number |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
246 this.height: number |
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 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
|
249 enddef |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
250 endclass |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
251 < |
31579 | 252 *class-member* *:static* *E1337* *E1338* |
31335
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
253 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
|
254 prefix: > |
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 class OtherThing |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
257 this.size: number |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
258 static totalSize: number |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
259 |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
260 def new(this.size) |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
261 totalSize += this.size |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
262 enddef |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
263 endclass |
31671 | 264 < *E1340* *E1341* |
265 Since the name is used as-is, shadowing the name by a function argument name | |
266 or variable name is not allowed. | |
267 | |
268 Just like object members the access can be made private by using an underscore | |
269 as the first character in the name, and it can be made public by prefixing | |
270 "public": > | |
271 class OtherThing | |
272 static total: number # anybody can read, only class can write | |
273 static _sum: number # only class can read and write | |
274 public static result: number # anybody can read and write | |
275 endclass | |
31335
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
276 < |
31671 | 277 *class-function* |
278 Class functions are also declared with "static". They have no access to | |
279 object members, they cannot use the "this" keyword. > | |
31335
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
280 |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
281 class OtherThing |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
282 this.size: number |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
283 static totalSize: number |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
284 |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
285 " 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
|
286 static def ClearTotalSize(): number |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
287 var prev = totalSize |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
288 totalSize = 0 |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
289 return prev |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
290 enddef |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
291 endclass |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
292 |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
293 |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
294 ============================================================================== |
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 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
|
297 |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
298 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
|
299 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
|
300 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
|
301 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
|
302 |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
303 abstract class Shape |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
304 this.color = Color.Black |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
305 this.thickness = 10 |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
306 endclass |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
307 |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
308 interface HasSurface |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
309 def Surface(): number |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
310 endinterface |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
311 |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
312 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
|
313 this.size: number |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
314 |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
315 def new(this.size) |
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 |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
318 def Surface(): number |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
319 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
|
320 enddef |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
321 endclass |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
322 |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
323 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
|
324 this.base: number |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
325 this.height: number |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
326 |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
327 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
|
328 enddef |
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 def Surface(): number |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
331 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
|
332 enddef |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
333 endclass |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
334 |
31671 | 335 If a class declares to implement an interface, all the items specified in the |
336 interface must appear in the class, with the same types. *E1348* *E1349* | |
337 | |
31335
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
338 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
|
339 |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
340 var shapes: list<HasSurface> = [ |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
341 Square.new(12), |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
342 Triangle.new(8, 15), |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
343 ] |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
344 for shape in shapes |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
345 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
|
346 endfor |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
347 |
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 ============================================================================== |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
350 |
31430 | 351 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
|
352 |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
353 Defining a class ~ |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
354 *:class* *:endclass* *:abstract* |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
355 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
|
356 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
|
357 |
31430 | 358 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
|
359 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
|
360 |
31335
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
361 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
|
362 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
|
363 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
|
364 |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
365 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
|
366 these variants: > |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
367 |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
368 class ClassName |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
369 endclass |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
370 |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
371 export class ClassName |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
372 endclass |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
373 |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
374 abstract class ClassName |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
375 endclass |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
376 |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
377 export abstract class ClassName |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
378 endclass |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
379 < |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
380 *E1314* |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
381 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
|
382 That avoids clashing with builtin types. |
31430 | 383 *E1315* |
31335
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
384 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
|
385 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
|
386 extends ClassName |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
387 implements InterfaceName, OtherInterface |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
388 specifies SomeInterface |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
389 < *extends* |
31671 | 390 A class can extend one other class. *E1352* *E1353* *E1354* |
391 *implements* *E1346* *E1347* | |
392 A class can implement one or more interfaces. The "implements" keyword can | |
393 only appear once *E1350* . Multiple interfaces can be specified, separated by | |
394 commas. Each interface name can appear only once. *E1351* | |
31335
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
395 *specifies* |
31396
307f68a41b03
patch 9.0.1031: Vim9 class is not implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
31335
diff
changeset
|
396 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
|
397 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
|
398 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
|
399 |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
400 |
31430 | 401 Items in a class ~ |
402 *E1318* *E1325* *E1326* | |
403 Inside a class, in betweeen `:class` and `:endclass`, these items can appear: | |
404 - An object member declaration: > | |
405 this._memberName: memberType | |
406 this.memberName: memberType | |
407 public this.memberName: memberType | |
408 - A constructor method: > | |
409 def new(arguments) | |
410 def newName(arguments) | |
411 - An object method: > | |
412 def SomeMethod(arguments) | |
31579 | 413 < *E1329* |
414 For the object member the type must be specified. The best way is to do this | |
415 explicitly with ": {type}". For simple types you can also use an initializer, | |
416 such as "= 123", and Vim will see that the type is a number. Avoid doing this | |
417 for more complex types and when the type will be incomplete. For example: > | |
418 this.nameList = [] | |
419 This specifies a list, but the item type is unknown. Better use: > | |
420 this.nameList: list<string> | |
421 The initialization isn't needed, the list is empty by default. | |
422 *E1330* | |
423 Some types cannot be used, such as "void", "null" and "v:none". | |
31430 | 424 |
425 | |
31335
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
426 Defining an interface ~ |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
427 *:interface* *:endinterface* |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
428 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
|
429 prefixed with `:export`: > |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
430 |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
431 interface InterfaceName |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
432 endinterface |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
433 |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
434 export interface InterfaceName |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
435 endinterface |
31671 | 436 < *E1344* |
31335
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
437 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
|
438 initializer. |
31671 | 439 *E1345* |
31335
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
440 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
|
441 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
|
442 |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
443 interface HasSurface |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
444 this.size: number |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
445 def Surface(): number |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
446 endinterface |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
447 |
31671 | 448 An interface name must start with an uppercase letter. *E1343* |
31335
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
449 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
|
450 name, with a hint about what it provides. |
31671 | 451 An interface can only be defined in a |Vim9| script file. *E1342* |
31335
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
452 |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
453 |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
454 Default constructor ~ |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
455 |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
456 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
|
457 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
|
458 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
|
459 |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
460 class AutoNew |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
461 this.name: string |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
462 this.age: number |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
463 this.gender: Gender |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
464 endclass |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
465 |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
466 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
|
467 |
31441
e572ff386670
patch 9.0.1053: default constructor arguments are not optional
Bram Moolenaar <Bram@vim.org>
parents:
31430
diff
changeset
|
468 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
|
469 enddef |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
470 |
31441
e572ff386670
patch 9.0.1053: default constructor arguments are not optional
Bram Moolenaar <Bram@vim.org>
parents:
31430
diff
changeset
|
471 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
|
472 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
|
473 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
|
474 with default values: > |
31430 | 475 |
476 class TextPosition | |
477 this.lnum: number = 1 | |
478 this.col: number = 1 | |
479 endclass | |
480 | |
481 If you want the constructor to have mandatory arguments, you need to write it | |
482 yourself. For example, if for the AutoNew class above you insist on getting | |
483 the name, you can define the constructor like this: > | |
484 | |
31441
e572ff386670
patch 9.0.1053: default constructor arguments are not optional
Bram Moolenaar <Bram@vim.org>
parents:
31430
diff
changeset
|
485 def new(this.name, this.age = v:none, this.gender = v:none) |
31430 | 486 enddef |
31441
e572ff386670
patch 9.0.1053: default constructor arguments are not optional
Bram Moolenaar <Bram@vim.org>
parents:
31430
diff
changeset
|
487 < *E1328* |
e572ff386670
patch 9.0.1053: default constructor arguments are not optional
Bram Moolenaar <Bram@vim.org>
parents:
31430
diff
changeset
|
488 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
|
489 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
|
490 way you only need to look in one place for the default values. |
31430 | 491 |
31671 | 492 All object members will be used in the default constructor, also private |
493 access ones. | |
494 | |
495 If the class extends another one, the object members of that class will come | |
496 first. | |
497 | |
31335
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 Multiple constructors ~ |
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 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
|
502 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
|
503 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
|
504 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
|
505 |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
506 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
|
507 enddef |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
508 ... |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
509 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
|
510 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
|
511 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
|
512 |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
513 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
|
514 includes it: > |
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 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
|
517 this.color = Color.black |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
518 enddef |
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 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
|
521 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
|
522 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
|
523 |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
524 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
|
525 "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
|
526 constructor methods. |
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 |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
529 ============================================================================== |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
530 |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
531 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
|
532 |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
533 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
|
534 |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
535 :type ListOfStrings list<string> |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
536 |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
537 TODO: more explanation |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
538 |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
539 |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
540 ============================================================================== |
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 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
|
543 |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
544 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
|
545 |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
546 :enum Color |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
547 White |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
548 Red |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
549 Green |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
550 Blue |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
551 Black |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
552 :endenum |
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 TODO: more explanation |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
555 |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
556 |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
557 ============================================================================== |
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 9. Rationale |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
560 |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
561 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
|
562 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
|
563 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
|
564 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
|
565 |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
566 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
|
567 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
|
568 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
|
569 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
|
570 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
|
571 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
|
572 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
|
573 |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
574 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
|
575 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
|
576 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
|
577 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
|
578 understand. |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
579 |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
580 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
|
581 - Keep it simple. |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
582 - 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
|
583 - 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
|
584 - 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
|
585 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
|
586 - Keep it consistent. |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
587 - 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
|
588 |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
589 |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
590 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
|
591 |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
592 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
|
593 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
|
594 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
|
595 disadvantage. |
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 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
|
598 "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
|
599 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
|
600 |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
601 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
|
602 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
|
603 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
|
604 |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
605 |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
606 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
|
607 |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
608 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
|
609 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
|
610 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
|
611 constructor. |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
612 |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
613 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
|
614 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
|
615 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
|
616 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
|
617 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
|
618 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
|
619 returning. |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
620 |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
621 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
|
622 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
|
623 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
|
624 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
|
625 |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
626 |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
627 No overloading of methods ~ |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
628 |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
629 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
|
630 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
|
631 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
|
632 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
|
633 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
|
634 |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
635 |
31671 | 636 Single inheritance and interfaces ~ |
637 | |
638 Some languages support multiple inheritance. Although that can be useful in | |
639 some cases, it makes the rules of how a class works quite complicated. | |
640 Instead, using interfaces to declare what is supported is much simpler. The | |
641 very popular Java language does it this way, and it should be good enough for | |
642 Vim. The "keep it simple" rule applies here. | |
643 | |
644 Explicitly declaring that a class supports an interface makes it easy to see | |
645 what a class is intended for. It also makes it possible to do proper type | |
646 checking. When an interface is changed any class that declares to implement | |
647 it will be checked if that change was also changed. The mechanism to assume a | |
648 class implements an interface just because the methods happen to match is | |
649 brittle and leads to obscure problems, let's not do that. | |
650 | |
651 | |
31335
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
652 Using "this.member" everywhere ~ |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
653 |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
654 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
|
655 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
|
656 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
|
657 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
|
658 |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
659 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
|
660 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
|
661 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
|
662 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
|
663 |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
664 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
|
665 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
|
666 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
|
667 aren't. |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
668 |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
669 |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
670 Using class members ~ |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
671 |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
672 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
|
673 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
|
674 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
|
675 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
|
676 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
|
677 |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
678 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
|
679 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
|
680 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
|
681 be changed too. |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
682 |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
683 |
31671 | 684 Declaring object and class members ~ |
685 | |
686 The main choice is whether to use "var" as with variable declarations. | |
687 TypeScript does not use it: > | |
688 class Point { | |
689 x: number; | |
690 y = 0; | |
691 } | |
692 | |
693 Following that Vim object members could be declared like this: > | |
694 class Point | |
695 this.x: number | |
696 this.y = 0 | |
697 endclass | |
698 | |
699 Some users pointed out that this looks more like an assignment than a | |
700 declaration. Adding "var" changes that: > | |
701 class Point | |
702 var this.x: number | |
703 var this.y = 0 | |
704 endclass | |
705 | |
706 We also need to be able to declare class members using the "static" keyword. | |
707 There we can also choose to leave out "var": > | |
708 class Point | |
709 var this.x: number | |
710 static count = 0 | |
711 endclass | |
712 | |
713 Or do use it, before "static": > | |
714 class Point | |
715 var this.x: number | |
716 var static count = 0 | |
717 endclass | |
718 | |
719 Or after "static": > | |
720 class Point | |
721 var this.x: number | |
722 static var count = 0 | |
723 endclass | |
724 | |
725 This is more in line with "static def Func()". | |
726 | |
727 There is no clear preference whether to use "var" or not. The two main | |
728 reasons to leave it out are: | |
729 1. TypeScript, Java and other popular languages do not use it. | |
730 2. Less clutter. | |
731 | |
732 | |
31335
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
733 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
|
734 |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
735 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
|
736 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
|
737 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
|
738 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
|
739 |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
740 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
|
741 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
|
742 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
|
743 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
|
744 |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
745 |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
746 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
|
747 |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
748 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
|
749 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
|
750 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
|
751 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
|
752 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
|
753 objects. |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
754 |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
755 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
|
756 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
|
757 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
|
758 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
|
759 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
|
760 |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
761 |
31396
307f68a41b03
patch 9.0.1031: Vim9 class is not implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
31335
diff
changeset
|
762 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
|
763 |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
764 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
|
765 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
|
766 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
|
767 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
|
768 |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
769 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
|
770 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
|
771 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
|
772 to find and change. |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
773 |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
774 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
|
775 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
|
776 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
|
777 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
|
778 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
|
779 |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
780 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
|
781 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
|
782 number of keywords. |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
783 |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
784 |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
785 No protected object members ~ |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
786 |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
787 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
|
788 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
|
789 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
|
790 |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
791 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
|
792 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
|
793 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
|
794 |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
795 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
|
796 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
|
797 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
|
798 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
|
799 |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
800 |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
801 ============================================================================== |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
802 |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
803 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
|
804 |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
805 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
|
806 the restrictions? |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
807 |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
808 Thoughts: |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
809 - 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
|
810 - 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
|
811 - 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
|
812 |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
813 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
|
814 - For testing: Mock mechanism |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
815 |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
816 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
|
817 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
|
818 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
|
819 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
|
820 |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
821 |
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
822 vim:tw=78:ts=8:noet:ft=help:norl: |