Mercurial > vim
annotate runtime/doc/vim9class.txt @ 33029:c7591e326ded v9.0.1806
patch 9.0.1806: Vim9: bogus error on export
Commit: https://github.com/vim/vim/commit/90c27b28032ea2b42718f8933f877a8bca2821ef
Author: LemonBoy <thatlemon@gmail.com>
Date: Sun Aug 27 19:28:15 2023 +0200
patch 9.0.1806: Vim9: bogus error on export
Problem: Vim9: bogus error on export
Solution: Don't error out when the export command is not executed
closes: #12912
closes: #12930
Signed-off-by: Christian Brabandt <cb@256bit.org>
Co-authored-by: LemonBoy <thatlemon@gmail.com>
| author | Christian Brabandt <cb@256bit.org> |
|---|---|
| date | Sun, 27 Aug 2023 19:45:02 +0200 |
| parents | 1d18c7fe609f |
| children | d42927c6e556 |
| rev | line source |
|---|---|
| 32294 | 1 *vim9class.txt* For Vim version 9.0. Last change: 2023 Mar 22 |
|
31335
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
2 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
3 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
4 VIM REFERENCE MANUAL by Bram Moolenaar |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
5 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
6 |
| 31885 | 7 NOTE - This is not finished yet, anything can still change! - NOTE |
|
31335
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
8 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
9 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
10 Vim9 classes, objects, interfaces, types and enums. |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
11 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
12 1. Overview |Vim9-class-overview| |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
13 2. A simple class |Vim9-simple-class| |
| 31885 | 14 3. Class members and functions |Vim9-class-member| |
| 15 4. Using an abstract class |Vim9-abstract-class| | |
| 16 5. Using an interface |Vim9-using-interface| | |
| 17 6. More class details |Vim9-class| | |
| 18 7. Type definition |Vim9-type| | |
| 19 8. Enum |Vim9-enum| | |
|
31335
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
20 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
21 9. Rationale |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
22 10. To be done later |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
23 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
24 ============================================================================== |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
25 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
26 1. Overview *Vim9-class-overview* |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
27 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
28 The fancy term is "object-oriented programming". You can find lots of study |
| 31885 | 29 material on this subject. Here we document what |Vim9| script provides, |
| 30 assuming you know the basics already. Added are helpful hints about how to | |
| 31 use this functionality effectively. | |
|
31335
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
32 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
33 The basic item is an object: |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
34 - An object stores state. It contains one or more variables that can each |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
35 have a value. |
| 31885 | 36 - An object provides functions that use and manipulate its state. These |
|
31335
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
37 functions are invoked "on the object", which is what sets it apart from the |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
38 traditional separation of data and code that manipulates the data. |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
39 - An object has a well defined interface, with typed member variables and |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
40 member functions. |
| 31885 | 41 - Objects are created from a class and all objects have the same interface. |
| 42 This does not change at runtime, it is not dynamic. | |
|
31335
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
43 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
44 An object can only be created by a class. A class provides: |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
45 - A new() method, the constructor, which returns an object for the class. |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
46 This method is invoked on the class name: MyClass.new(). |
| 31885 | 47 - State shared by all objects of the class: class variables (class members). |
|
31335
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
48 - A hierarchy of classes, with super-classes and sub-classes, inheritance. |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
49 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
50 An interface is used to specify properties of an object: |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
51 - An object can declare several interfaces that it implements. |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
52 - Different objects implementing the same interface can be used the same way. |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
53 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
54 The class hierarchy allows for single inheritance. Otherwise interfaces are |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
55 to be used where needed. |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
56 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
57 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
58 Class modeling ~ |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
59 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
60 You can model classes any way you like. Keep in mind what you are building, |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
61 don't try to model the real world. This can be confusing, especially because |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
62 teachers use real-world objects to explain class relations and you might think |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
63 your model should therefore reflect the real world. It doesn't! The model |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
64 should match your purpose. |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
65 |
| 31885 | 66 Keep in mind that composition (an object contains other objects) is often |
| 67 better than inheritance (an object extends another object). Don't waste time | |
| 68 trying to find the optimal class model. Or waste time discussing whether a | |
| 69 square is a rectangle or that a rectangle is a square. It doesn't matter. | |
|
31335
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
70 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
71 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
72 ============================================================================== |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
73 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
74 2. A simple class *Vim9-simple-class* |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
75 |
| 31885 | 76 Let's start with a simple example: a class that stores a text position (see |
| 77 below for how to do this more efficiently): > | |
|
31335
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
78 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
79 class TextPosition |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
80 this.lnum: number |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
81 this.col: number |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
82 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
83 def new(lnum: number, col: number) |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
84 this.lnum = lnum |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
85 this.col = col |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
86 enddef |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
87 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
88 def SetLnum(lnum: number) |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
89 this.lnum = lnum |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
90 enddef |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
91 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
92 def SetCol(col: number) |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
93 this.col = col |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
94 enddef |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
95 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
96 def SetPosition(lnum: number, col: number) |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
97 this.lnum = lnum |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
98 this.col = col |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
99 enddef |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
100 endclass |
| 31430 | 101 < *object* *Object* |
|
31335
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
102 You can create an object from this class with the new() method: > |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
103 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
104 var pos = TextPosition.new(1, 1) |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
105 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
106 The object members "lnum" and "col" can be accessed directly: > |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
107 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
108 echo $'The text position is ({pos.lnum}, {pos.col})' |
| 31430 | 109 < *E1317* *E1327* |
|
31335
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
110 If you have been using other object-oriented languages you will notice that |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
111 in Vim the object members are consistently referred to with the "this." |
| 31885 | 112 prefix. This is different from languages like Java and TypeScript. The |
|
31335
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
113 naming convention makes the object members easy to spot. Also, when a |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
114 variable does not have the "this." prefix you know it is not an object member. |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
115 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
116 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
117 Member write access ~ |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
118 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
119 Now try to change an object member directly: > |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
120 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
121 pos.lnum = 9 |
| 31885 | 122 < *E1335* |
|
31335
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
123 This will give you an error! That is because by default object members can be |
| 31885 | 124 read but not set. That's why the TextPosition class provides a method for it: > |
|
31335
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
125 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
126 pos.SetLnum(9) |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
127 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
128 Allowing to read but not set an object member is the most common and safest |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
129 way. Most often there is no problem using a value, while setting a value may |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
130 have side effects that need to be taken care of. In this case, the SetLnum() |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
131 method could check if the line number is valid and either give an error or use |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
132 the closest valid value. |
| 31885 | 133 *:public* *E1331* |
|
31335
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
134 If you don't care about side effects and want to allow the object member to be |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
135 changed at any time, you can make it public: > |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
136 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
137 public this.lnum: number |
| 31885 | 138 public this.col: number |
|
31335
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
139 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
140 Now you don't need the SetLnum(), SetCol() and SetPosition() methods, setting |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
141 "pos.lnum" directly above will no longer give an error. |
| 31579 | 142 *E1334* |
| 143 If you try to set an object member that doesn't exist you get an error: > | |
| 144 pos.other = 9 | |
| 145 < E1334: Object member not found: other ~ | |
|
31335
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
146 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
147 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
148 Private members ~ |
| 31579 | 149 *E1332* *E1333* |
|
31335
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
150 On the other hand, if you do not want the object members to be read directly, |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
151 you can make them private. This is done by prefixing an underscore to the |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
152 name: > |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
153 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
154 this._lnum: number |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
155 this._col number |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
156 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
157 Now you need to provide methods to get the value of the private members. |
| 31885 | 158 These are commonly called getters. We recommend using a name that starts with |
|
31335
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
159 "Get": > |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
160 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
161 def GetLnum(): number |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
162 return this._lnum |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
163 enddef |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
164 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
165 def GetCol() number |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
166 return this._col |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
167 enddef |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
168 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
169 This example isn't very useful, the members might as well have been public. |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
170 It does become useful if you check the value. For example, restrict the line |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
171 number to the total number of lines: > |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
172 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
173 def GetLnum(): number |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
174 if this._lnum > this._lineCount |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
175 return this._lineCount |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
176 endif |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
177 return this._lnum |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
178 enddef |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
179 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
180 |
|
33025
1d18c7fe609f
patch 9.0.1804: Vim9: no support for private object methods
Christian Brabandt <cb@256bit.org>
parents:
32960
diff
changeset
|
181 Private methods ~ |
|
1d18c7fe609f
patch 9.0.1804: Vim9: no support for private object methods
Christian Brabandt <cb@256bit.org>
parents:
32960
diff
changeset
|
182 If you want object methods to be accessible only from other methods of the |
|
1d18c7fe609f
patch 9.0.1804: Vim9: no support for private object methods
Christian Brabandt <cb@256bit.org>
parents:
32960
diff
changeset
|
183 same class and not used from outside the class, then you can make them |
|
1d18c7fe609f
patch 9.0.1804: Vim9: no support for private object methods
Christian Brabandt <cb@256bit.org>
parents:
32960
diff
changeset
|
184 private. This is done by prefixing the method name with an underscore: > |
|
1d18c7fe609f
patch 9.0.1804: Vim9: no support for private object methods
Christian Brabandt <cb@256bit.org>
parents:
32960
diff
changeset
|
185 |
|
1d18c7fe609f
patch 9.0.1804: Vim9: no support for private object methods
Christian Brabandt <cb@256bit.org>
parents:
32960
diff
changeset
|
186 class SomeClass |
|
1d18c7fe609f
patch 9.0.1804: Vim9: no support for private object methods
Christian Brabandt <cb@256bit.org>
parents:
32960
diff
changeset
|
187 def _Foo(): number |
|
1d18c7fe609f
patch 9.0.1804: Vim9: no support for private object methods
Christian Brabandt <cb@256bit.org>
parents:
32960
diff
changeset
|
188 return 10 |
|
1d18c7fe609f
patch 9.0.1804: Vim9: no support for private object methods
Christian Brabandt <cb@256bit.org>
parents:
32960
diff
changeset
|
189 enddef |
|
1d18c7fe609f
patch 9.0.1804: Vim9: no support for private object methods
Christian Brabandt <cb@256bit.org>
parents:
32960
diff
changeset
|
190 def Bar(): number |
|
1d18c7fe609f
patch 9.0.1804: Vim9: no support for private object methods
Christian Brabandt <cb@256bit.org>
parents:
32960
diff
changeset
|
191 return this._Foo() |
|
1d18c7fe609f
patch 9.0.1804: Vim9: no support for private object methods
Christian Brabandt <cb@256bit.org>
parents:
32960
diff
changeset
|
192 enddef |
|
1d18c7fe609f
patch 9.0.1804: Vim9: no support for private object methods
Christian Brabandt <cb@256bit.org>
parents:
32960
diff
changeset
|
193 endclass |
|
1d18c7fe609f
patch 9.0.1804: Vim9: no support for private object methods
Christian Brabandt <cb@256bit.org>
parents:
32960
diff
changeset
|
194 < |
|
1d18c7fe609f
patch 9.0.1804: Vim9: no support for private object methods
Christian Brabandt <cb@256bit.org>
parents:
32960
diff
changeset
|
195 Accessing a private method outside the class will result in an error (using |
|
1d18c7fe609f
patch 9.0.1804: Vim9: no support for private object methods
Christian Brabandt <cb@256bit.org>
parents:
32960
diff
changeset
|
196 the above class): > |
|
1d18c7fe609f
patch 9.0.1804: Vim9: no support for private object methods
Christian Brabandt <cb@256bit.org>
parents:
32960
diff
changeset
|
197 |
|
1d18c7fe609f
patch 9.0.1804: Vim9: no support for private object methods
Christian Brabandt <cb@256bit.org>
parents:
32960
diff
changeset
|
198 var a = SomeClass.new() |
|
1d18c7fe609f
patch 9.0.1804: Vim9: no support for private object methods
Christian Brabandt <cb@256bit.org>
parents:
32960
diff
changeset
|
199 a._Foo() |
|
1d18c7fe609f
patch 9.0.1804: Vim9: no support for private object methods
Christian Brabandt <cb@256bit.org>
parents:
32960
diff
changeset
|
200 < |
|
31335
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
201 Simplifying the new() method ~ |
|
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 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
|
204 this pattern: > |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
205 |
| 31885 | 206 class SomeClass |
|
31335
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
207 this.lnum: number |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
208 this.col: number |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
209 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
210 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
|
211 this.lnum = lnum |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
212 this.col = col |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
213 enddef |
| 31885 | 214 endclass |
|
31335
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 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
|
217 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
|
218 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
219 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
|
220 enddef |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
221 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
222 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
|
223 including "this.", as the argument to new() means the value provided in the |
| 31885 | 224 new() call is assigned to that object member. This mechanism comes from the |
| 225 Dart language. | |
| 226 | |
| 227 Putting together this way of using new() and making the members public results | |
| 32294 | 228 in a much shorter class definition than what we started with: > |
| 31885 | 229 |
| 230 class TextPosition | |
| 231 public this.lnum: number | |
| 232 public this.col: number | |
| 233 | |
| 234 def new(this.lnum, this.col) | |
| 235 enddef | |
| 236 | |
| 237 def SetPosition(lnum: number, col: number) | |
| 238 this.lnum = lnum | |
| 239 this.col = col | |
| 240 enddef | |
| 241 endclass | |
|
31335
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
242 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
243 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
|
244 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
|
245 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
|
246 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
|
247 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
|
248 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
|
249 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
|
250 |
| 31885 | 251 If the class extends a parent class, the same thing happens. In the second |
| 252 step the members of the parent class are done first. There is no need to call | |
| 253 "super()" or "new()" on the parent. | |
|
31335
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
254 |
|
32903
54c01bb98b8e
patch 9.0.1760: vim9 class problem with new() constructor
Christian Brabandt <cb@256bit.org>
parents:
32294
diff
changeset
|
255 When defining the new() method the return type should not be specified. It |
|
54c01bb98b8e
patch 9.0.1760: vim9 class problem with new() constructor
Christian Brabandt <cb@256bit.org>
parents:
32294
diff
changeset
|
256 always returns an object of the class. |
|
54c01bb98b8e
patch 9.0.1760: vim9 class problem with new() constructor
Christian Brabandt <cb@256bit.org>
parents:
32294
diff
changeset
|
257 |
|
31335
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
258 ============================================================================== |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
259 |
| 31885 | 260 3. class members and functions *Vim9-class-member* |
| 261 | |
| 262 *:static* *E1337* *E1338* | |
| 263 Class members are declared with "static". They are used by the name without a | |
| 264 prefix: > | |
| 265 | |
| 266 class OtherThing | |
| 267 this.size: number | |
| 268 static totalSize: number | |
| 269 | |
| 270 def new(this.size) | |
| 271 totalSize += this.size | |
| 272 enddef | |
| 273 endclass | |
| 274 < *E1340* *E1341* | |
| 275 Since the name is used as-is, shadowing the name by a function argument name | |
| 276 or local variable name is not allowed. | |
| 277 | |
| 278 Just like object members the access can be made private by using an underscore | |
| 279 as the first character in the name, and it can be made public by prefixing | |
| 280 "public": > | |
| 281 | |
| 282 class OtherThing | |
| 283 static total: number # anybody can read, only class can write | |
| 284 static _sum: number # only class can read and write | |
| 285 public static result: number # anybody can read and write | |
| 286 endclass | |
| 287 < | |
| 288 *class-function* | |
| 289 Class functions are also declared with "static". They have no access to | |
| 290 object members, they cannot use the "this" keyword. > | |
| 291 | |
| 292 class OtherThing | |
| 293 this.size: number | |
| 294 static totalSize: number | |
| 295 | |
| 296 # Clear the total size and return the value it had before. | |
| 297 static def ClearTotalSize(): number | |
| 298 var prev = totalSize | |
| 299 totalSize = 0 | |
| 300 return prev | |
| 301 enddef | |
| 302 endclass | |
| 303 | |
| 304 Inside the class the function can be called by name directly, outside the | |
| 305 class the class name must be prefixed: `OtherThing.ClearTotalSize()`. | |
| 306 | |
|
33025
1d18c7fe609f
patch 9.0.1804: Vim9: no support for private object methods
Christian Brabandt <cb@256bit.org>
parents:
32960
diff
changeset
|
307 Just like object methods the access can be made private by using an underscore |
|
1d18c7fe609f
patch 9.0.1804: Vim9: no support for private object methods
Christian Brabandt <cb@256bit.org>
parents:
32960
diff
changeset
|
308 as the first character in the method name: > |
|
1d18c7fe609f
patch 9.0.1804: Vim9: no support for private object methods
Christian Brabandt <cb@256bit.org>
parents:
32960
diff
changeset
|
309 |
|
1d18c7fe609f
patch 9.0.1804: Vim9: no support for private object methods
Christian Brabandt <cb@256bit.org>
parents:
32960
diff
changeset
|
310 class OtherThing |
|
1d18c7fe609f
patch 9.0.1804: Vim9: no support for private object methods
Christian Brabandt <cb@256bit.org>
parents:
32960
diff
changeset
|
311 static def _Foo() |
|
1d18c7fe609f
patch 9.0.1804: Vim9: no support for private object methods
Christian Brabandt <cb@256bit.org>
parents:
32960
diff
changeset
|
312 echo "Foo" |
|
1d18c7fe609f
patch 9.0.1804: Vim9: no support for private object methods
Christian Brabandt <cb@256bit.org>
parents:
32960
diff
changeset
|
313 enddef |
|
1d18c7fe609f
patch 9.0.1804: Vim9: no support for private object methods
Christian Brabandt <cb@256bit.org>
parents:
32960
diff
changeset
|
314 def Bar() |
|
1d18c7fe609f
patch 9.0.1804: Vim9: no support for private object methods
Christian Brabandt <cb@256bit.org>
parents:
32960
diff
changeset
|
315 OtherThing._Foo() |
|
1d18c7fe609f
patch 9.0.1804: Vim9: no support for private object methods
Christian Brabandt <cb@256bit.org>
parents:
32960
diff
changeset
|
316 enddef |
|
1d18c7fe609f
patch 9.0.1804: Vim9: no support for private object methods
Christian Brabandt <cb@256bit.org>
parents:
32960
diff
changeset
|
317 endclass |
|
1d18c7fe609f
patch 9.0.1804: Vim9: no support for private object methods
Christian Brabandt <cb@256bit.org>
parents:
32960
diff
changeset
|
318 |
| 31885 | 319 ============================================================================== |
| 320 | |
| 321 4. Using an abstract class *Vim9-abstract-class* | |
|
31335
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
322 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
323 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
|
324 model one often finds that a few classes have the same properties that can be |
| 31885 | 325 shared, but a class with these properties does not have enough state to create |
|
31335
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
326 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
|
327 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
|
328 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
329 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
|
330 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
|
331 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
|
332 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
|
333 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
334 abstract class Shape |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
335 this.color = Color.Black |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
336 this.thickness = 10 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
337 endclass |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
338 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
339 class Square extends Shape |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
340 this.size: number |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
341 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
342 def new(this.size) |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
343 enddef |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
344 endclass |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
345 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
346 class Triangle extends Shape |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
347 this.base: number |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
348 this.height: number |
|
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 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
|
351 enddef |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
352 endclass |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
353 < |
| 31885 | 354 An abstract class is defined the same way as a normal class, except that it |
| 355 does not have any new() method. *E1359* | |
|
31335
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
356 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
357 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
358 ============================================================================== |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
359 |
| 31885 | 360 5. Using an interface *Vim9-using-interface* |
|
31335
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
361 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
362 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
|
363 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
|
364 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
|
365 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
|
366 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
367 abstract class Shape |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
368 this.color = Color.Black |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
369 this.thickness = 10 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
370 endclass |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
371 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
372 interface HasSurface |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
373 def Surface(): number |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
374 endinterface |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
375 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
376 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
|
377 this.size: number |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
378 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
379 def new(this.size) |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
380 enddef |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
381 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
382 def Surface(): number |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
383 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
|
384 enddef |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
385 endclass |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
386 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
387 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
|
388 this.base: number |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
389 this.height: number |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
390 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
391 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
|
392 enddef |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
393 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
394 def Surface(): number |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
395 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
|
396 enddef |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
397 endclass |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
398 |
| 31671 | 399 If a class declares to implement an interface, all the items specified in the |
| 400 interface must appear in the class, with the same types. *E1348* *E1349* | |
| 401 | |
|
31335
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
402 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
|
403 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
404 var shapes: list<HasSurface> = [ |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
405 Square.new(12), |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
406 Triangle.new(8, 15), |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
407 ] |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
408 for shape in shapes |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
409 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
|
410 endfor |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
411 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
412 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
413 ============================================================================== |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
414 |
| 31885 | 415 6. More class details *Vim9-class* *Class* *class* |
|
31335
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
416 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
417 Defining a class ~ |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
418 *:class* *:endclass* *:abstract* |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
419 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
|
420 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
|
421 |
| 31430 | 422 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
|
423 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
|
424 |
|
31335
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
425 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
|
426 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
|
427 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
|
428 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
429 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
|
430 these variants: > |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
431 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
432 class ClassName |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
433 endclass |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
434 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
435 export class ClassName |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
436 endclass |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
437 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
438 abstract class ClassName |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
439 endclass |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
440 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
441 export abstract class ClassName |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
442 endclass |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
443 < |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
444 *E1314* |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
445 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
|
446 That avoids clashing with builtin types. |
| 31430 | 447 *E1315* |
|
31335
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
448 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
|
449 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
|
450 extends ClassName |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
451 implements InterfaceName, OtherInterface |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
452 specifies SomeInterface |
| 31885 | 453 < *E1355* |
| 454 Each member and function name can be used only once. It is not possible to | |
| 455 define a function with the same name and different type of arguments. | |
| 456 | |
| 457 | |
|
32960
d5c05e15cf81
patch 9.0.1780: Vim9 type not defined during object creation
Christian Brabandt <cb@256bit.org>
parents:
32903
diff
changeset
|
458 Member Initialization ~ |
|
d5c05e15cf81
patch 9.0.1780: Vim9 type not defined during object creation
Christian Brabandt <cb@256bit.org>
parents:
32903
diff
changeset
|
459 If the type of a member is not explicitly specified in a class, then it is set |
|
d5c05e15cf81
patch 9.0.1780: Vim9 type not defined during object creation
Christian Brabandt <cb@256bit.org>
parents:
32903
diff
changeset
|
460 to "any" during class definition. When an object is instantiated from the |
|
d5c05e15cf81
patch 9.0.1780: Vim9 type not defined during object creation
Christian Brabandt <cb@256bit.org>
parents:
32903
diff
changeset
|
461 class, then the type of the member is set. |
|
d5c05e15cf81
patch 9.0.1780: Vim9 type not defined during object creation
Christian Brabandt <cb@256bit.org>
parents:
32903
diff
changeset
|
462 |
|
d5c05e15cf81
patch 9.0.1780: Vim9 type not defined during object creation
Christian Brabandt <cb@256bit.org>
parents:
32903
diff
changeset
|
463 |
| 31885 | 464 Extending a class ~ |
| 465 *extends* | |
| 31671 | 466 A class can extend one other class. *E1352* *E1353* *E1354* |
| 31885 | 467 The basic idea is to build on top of an existing class, add properties to it. |
| 468 | |
| 469 The extended class is called the "base class" or "super class". The new class | |
| 470 is called the "child class". | |
| 471 | |
| 472 Object members from the base class are all taken over by the child class. It | |
| 473 is not possible to override them (unlike some other languages). | |
| 474 | |
| 475 *E1356* *E1357* *E1358* | |
| 476 Object methods of the base class can be overruled. The signature (arguments, | |
| 477 argument types and return type) must be exactly the same. The method of the | |
| 478 base class can be called by prefixing "super.". | |
| 479 | |
| 480 Other object methods of the base class are taken over by the child class. | |
| 481 | |
| 482 Class functions, including functions starting with "new", can be overruled, | |
| 483 like with object methods. The function on the base class can be called by | |
| 484 prefixing the name of the class (for class functions) or "super.". | |
| 485 | |
| 486 Unlike other languages, the constructor of the base class does not need to be | |
| 487 invoked. In fact, it cannot be invoked. If some initialization from the base | |
| 488 class also needs to be done in a child class, put it in an object method and | |
| 489 call that method from every constructor(). | |
| 490 | |
| 491 If the base class did not specify a new() function then one was automatically | |
| 492 created. This function will not be taken over by the child class. The child | |
| 493 class can define its own new() function, or, if there isn't one, a new() | |
| 494 function will be added automatically. | |
| 495 | |
| 496 | |
| 497 A class implementing an interface ~ | |
| 31671 | 498 *implements* *E1346* *E1347* |
| 499 A class can implement one or more interfaces. The "implements" keyword can | |
| 500 only appear once *E1350* . Multiple interfaces can be specified, separated by | |
| 501 commas. Each interface name can appear only once. *E1351* | |
| 31885 | 502 |
| 503 | |
| 504 A class defining an interface ~ | |
|
31335
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
505 *specifies* |
|
31396
307f68a41b03
patch 9.0.1031: Vim9 class is not implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
31335
diff
changeset
|
506 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
|
507 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
|
508 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
|
509 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
510 |
| 31430 | 511 Items in a class ~ |
| 512 *E1318* *E1325* *E1326* | |
| 32061 | 513 Inside a class, in between `:class` and `:endclass`, these items can appear: |
| 31430 | 514 - An object member declaration: > |
| 32004 | 515 this._memberName: memberType |
| 516 this.memberName: memberType | |
| 31430 | 517 public this.memberName: memberType |
| 518 - A constructor method: > | |
| 32004 | 519 def new(arguments) |
| 520 def newName(arguments) | |
| 31430 | 521 - An object method: > |
| 32004 | 522 def SomeMethod(arguments) |
| 31579 | 523 < *E1329* |
| 524 For the object member the type must be specified. The best way is to do this | |
| 525 explicitly with ": {type}". For simple types you can also use an initializer, | |
| 526 such as "= 123", and Vim will see that the type is a number. Avoid doing this | |
| 527 for more complex types and when the type will be incomplete. For example: > | |
| 528 this.nameList = [] | |
| 529 This specifies a list, but the item type is unknown. Better use: > | |
| 530 this.nameList: list<string> | |
| 531 The initialization isn't needed, the list is empty by default. | |
| 532 *E1330* | |
| 533 Some types cannot be used, such as "void", "null" and "v:none". | |
| 31430 | 534 |
| 535 | |
|
31335
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
536 Defining an interface ~ |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
537 *:interface* *:endinterface* |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
538 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
|
539 prefixed with `:export`: > |
|
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 interface InterfaceName |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
542 endinterface |
|
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 export interface InterfaceName |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
545 endinterface |
| 31671 | 546 < *E1344* |
|
31335
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
547 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
|
548 initializer. |
| 31671 | 549 *E1345* |
|
31335
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
550 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
|
551 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
|
552 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
553 interface HasSurface |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
554 this.size: number |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
555 def Surface(): number |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
556 endinterface |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
557 |
| 31671 | 558 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
|
559 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
|
560 name, with a hint about what it provides. |
| 31671 | 561 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
|
562 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
563 |
| 32004 | 564 null object ~ |
| 565 | |
| 32061 | 566 When a variable is declared to have the type of an object, but it is not |
| 32004 | 567 initialized, the value is null. When trying to use this null object Vim often |
| 568 does not know what class was supposed to be used. Vim then cannot check if | |
| 569 a member name is correct and you will get an "Using a null object" error, | |
| 32294 | 570 even when the member name is invalid. *E1360* *E1362* *E1363* |
| 32004 | 571 |
| 572 | |
|
31335
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
573 Default constructor ~ |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
574 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
575 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
|
576 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
|
577 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
|
578 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
579 class AutoNew |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
580 this.name: string |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
581 this.age: number |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
582 this.gender: Gender |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
583 endclass |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
584 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
585 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
|
586 |
|
31441
e572ff386670
patch 9.0.1053: default constructor arguments are not optional
Bram Moolenaar <Bram@vim.org>
parents:
31430
diff
changeset
|
587 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
|
588 enddef |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
589 |
|
31441
e572ff386670
patch 9.0.1053: default constructor arguments are not optional
Bram Moolenaar <Bram@vim.org>
parents:
31430
diff
changeset
|
590 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
|
591 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
|
592 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
|
593 with default values: > |
| 31430 | 594 |
| 595 class TextPosition | |
| 596 this.lnum: number = 1 | |
| 597 this.col: number = 1 | |
| 598 endclass | |
| 599 | |
| 600 If you want the constructor to have mandatory arguments, you need to write it | |
| 601 yourself. For example, if for the AutoNew class above you insist on getting | |
| 602 the name, you can define the constructor like this: > | |
| 603 | |
|
31441
e572ff386670
patch 9.0.1053: default constructor arguments are not optional
Bram Moolenaar <Bram@vim.org>
parents:
31430
diff
changeset
|
604 def new(this.name, this.age = v:none, this.gender = v:none) |
| 31430 | 605 enddef |
|
31441
e572ff386670
patch 9.0.1053: default constructor arguments are not optional
Bram Moolenaar <Bram@vim.org>
parents:
31430
diff
changeset
|
606 < *E1328* |
|
e572ff386670
patch 9.0.1053: default constructor arguments are not optional
Bram Moolenaar <Bram@vim.org>
parents:
31430
diff
changeset
|
607 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
|
608 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
|
609 way you only need to look in one place for the default values. |
| 31430 | 610 |
| 31671 | 611 All object members will be used in the default constructor, also private |
| 612 access ones. | |
| 613 | |
| 614 If the class extends another one, the object members of that class will come | |
| 615 first. | |
| 616 | |
|
31335
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
617 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
618 Multiple constructors ~ |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
619 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
620 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
|
621 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
|
622 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
|
623 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
|
624 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
625 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
|
626 enddef |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
627 ... |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
628 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
|
629 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
|
630 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
|
631 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
632 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
|
633 includes it: > |
|
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 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
|
636 this.color = Color.black |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
637 enddef |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
638 ... |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
639 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
|
640 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
|
641 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
|
642 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
643 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
|
644 "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
|
645 constructor methods. |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
646 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
647 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
648 ============================================================================== |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
649 |
| 31885 | 650 7. Type definition *Vim9-type* *:type* |
|
31335
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
651 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
652 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
|
653 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
654 :type ListOfStrings list<string> |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
655 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
656 TODO: more explanation |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
657 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
658 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
659 ============================================================================== |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
660 |
| 31885 | 661 8. Enum *Vim9-enum* *:enum* *:endenum* |
|
31335
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
662 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
663 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
|
664 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
665 :enum Color |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
666 White |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
667 Red |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
668 Green |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
669 Blue |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
670 Black |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
671 :endenum |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
672 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
673 TODO: more explanation |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
674 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
675 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
676 ============================================================================== |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
677 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
678 9. Rationale |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
679 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
680 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
|
681 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
|
682 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
|
683 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
|
684 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
685 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
|
686 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
|
687 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
|
688 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
|
689 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
|
690 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
|
691 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
|
692 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
693 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
|
694 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
|
695 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
|
696 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
|
697 understand. |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
698 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
699 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
|
700 - Keep it simple. |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
701 - 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
|
702 - 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
|
703 - 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
|
704 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
|
705 - Keep it consistent. |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
706 - 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
|
707 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
708 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
709 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
|
710 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
711 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
|
712 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
|
713 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
|
714 disadvantage. |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
715 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
716 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
|
717 "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
|
718 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
|
719 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
720 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
|
721 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
|
722 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
|
723 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
724 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
725 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
|
726 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
727 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
|
728 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
|
729 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
|
730 constructor. |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
731 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
732 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
|
733 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
|
734 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
|
735 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
|
736 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
|
737 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
|
738 returning. |
|
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 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
|
741 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
|
742 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
|
743 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
|
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 No overloading of methods ~ |
|
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 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
|
749 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
|
750 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
|
751 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
|
752 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
|
753 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
754 |
| 31671 | 755 Single inheritance and interfaces ~ |
| 756 | |
| 757 Some languages support multiple inheritance. Although that can be useful in | |
| 758 some cases, it makes the rules of how a class works quite complicated. | |
| 759 Instead, using interfaces to declare what is supported is much simpler. The | |
| 760 very popular Java language does it this way, and it should be good enough for | |
| 31885 | 761 Vim. The "keep it simple" rule applies here. |
| 31671 | 762 |
| 763 Explicitly declaring that a class supports an interface makes it easy to see | |
| 764 what a class is intended for. It also makes it possible to do proper type | |
| 765 checking. When an interface is changed any class that declares to implement | |
| 766 it will be checked if that change was also changed. The mechanism to assume a | |
| 767 class implements an interface just because the methods happen to match is | |
| 768 brittle and leads to obscure problems, let's not do that. | |
| 769 | |
| 770 | |
|
31335
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
771 Using "this.member" everywhere ~ |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
772 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
773 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
|
774 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
|
775 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
|
776 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
|
777 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
778 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
|
779 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
|
780 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
|
781 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
|
782 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
783 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
|
784 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
|
785 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
|
786 aren't. |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
787 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
788 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
789 Using class members ~ |
|
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 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
|
792 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
|
793 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
|
794 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
|
795 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
|
796 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
797 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
|
798 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
|
799 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
|
800 be changed too. |
|
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 |
| 31671 | 803 Declaring object and class members ~ |
| 804 | |
| 805 The main choice is whether to use "var" as with variable declarations. | |
| 806 TypeScript does not use it: > | |
| 807 class Point { | |
| 808 x: number; | |
| 809 y = 0; | |
| 810 } | |
| 811 | |
| 812 Following that Vim object members could be declared like this: > | |
| 813 class Point | |
| 814 this.x: number | |
| 815 this.y = 0 | |
| 816 endclass | |
| 817 | |
| 818 Some users pointed out that this looks more like an assignment than a | |
| 819 declaration. Adding "var" changes that: > | |
| 820 class Point | |
| 821 var this.x: number | |
| 822 var this.y = 0 | |
| 823 endclass | |
| 824 | |
| 825 We also need to be able to declare class members using the "static" keyword. | |
| 826 There we can also choose to leave out "var": > | |
| 827 class Point | |
| 828 var this.x: number | |
| 829 static count = 0 | |
| 830 endclass | |
| 831 | |
| 832 Or do use it, before "static": > | |
| 833 class Point | |
| 834 var this.x: number | |
| 835 var static count = 0 | |
| 836 endclass | |
| 837 | |
| 838 Or after "static": > | |
| 839 class Point | |
| 840 var this.x: number | |
| 841 static var count = 0 | |
| 842 endclass | |
| 843 | |
| 844 This is more in line with "static def Func()". | |
| 845 | |
| 846 There is no clear preference whether to use "var" or not. The two main | |
| 847 reasons to leave it out are: | |
| 848 1. TypeScript, Java and other popular languages do not use it. | |
| 849 2. Less clutter. | |
| 850 | |
| 851 | |
|
31335
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
852 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
|
853 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
854 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
|
855 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
|
856 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
|
857 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
|
858 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
859 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
|
860 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
|
861 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
|
862 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
|
863 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
864 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
865 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
|
866 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
867 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
|
868 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
|
869 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
|
870 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
|
871 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
|
872 objects. |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
873 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
874 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
|
875 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
|
876 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
|
877 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
|
878 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
|
879 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
880 |
|
31396
307f68a41b03
patch 9.0.1031: Vim9 class is not implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
31335
diff
changeset
|
881 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
|
882 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
883 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
|
884 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
|
885 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
|
886 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
|
887 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
888 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
|
889 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
|
890 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
|
891 to find and change. |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
892 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
893 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
|
894 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
|
895 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
|
896 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
|
897 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
|
898 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
899 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
|
900 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
|
901 number of keywords. |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
902 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
903 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
904 No protected object members ~ |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
905 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
906 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
|
907 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
|
908 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
|
909 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
910 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
|
911 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
|
912 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
|
913 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
914 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
|
915 small team working on it. Complex rules then only make it more complicated, |
| 32294 | 916 the extra safety provided by the rules isn't really needed. Let's just keep |
| 917 it simple and not specify access details. | |
|
31335
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
918 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
919 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
920 ============================================================================== |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
921 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
922 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
|
923 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
924 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
|
925 the restrictions? |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
926 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
927 Thoughts: |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
928 - 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
|
929 - 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
|
930 - 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
|
931 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
932 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
|
933 - For testing: Mock mechanism |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
934 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
935 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
|
936 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
|
937 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
|
938 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
|
939 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
940 |
|
5acc0d2cf4f7
patch 9.0.1001: classes are not documented or implemented yet
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
941 vim:tw=78:ts=8:noet:ft=help:norl: |