Mercurial > vim
annotate runtime/doc/vim9.txt @ 26980:8796f1384750 v8.2.4019
patch 8.2.4019: Vim9: import mechanism is too complicated
Commit: https://github.com/vim/vim/commit/d5f400c607182db6d4fbe2964471d796277f67e8
Author: Bram Moolenaar <Bram@vim.org>
Date: Thu Jan 6 21:10:28 2022 +0000
patch 8.2.4019: Vim9: import mechanism is too complicated
Problem: Vim9: import mechanism is too complicated.
Solution: Do not use the Javascript mechanism but a much simpler one.
| author | Bram Moolenaar <Bram@vim.org> |
|---|---|
| date | Thu, 06 Jan 2022 22:15:04 +0100 |
| parents | be85735650f7 |
| children | 3e661b0cf500 |
| rev | line source |
|---|---|
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1 *vim9.txt* For Vim version 8.2. Last change: 2021 Dec 27 |
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2 |
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4 VIM REFERENCE MANUAL by Bram Moolenaar |
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6 |
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7 Vim9 script commands and expressions. *Vim9* *vim9* |
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8 |
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9 Most expression help is in |eval.txt|. This file is about the new syntax and |
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10 features in Vim9 script. |
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11 |
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12 |
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13 |
| 23466 | 14 1. What is Vim9 script? |Vim9-script| |
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15 2. Differences |vim9-differences| |
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16 3. New style functions |fast-functions| |
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17 4. Types |vim9-types| |
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18 5. Namespace, Import and Export |vim9script| |
| 22328 | 19 6. Future work: classes |vim9-classes| |
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20 |
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21 9. Rationale |vim9-rationale| |
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22 |
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23 ============================================================================== |
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24 |
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25 1. What is Vim9 script? *Vim9-script* |
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26 |
| 20241 | 27 Vim script has been growing over time, while preserving backwards |
| 28 compatibility. That means bad choices from the past often can't be changed | |
| 20965 | 29 and compatibility with Vi restricts possible solutions. Execution is quite |
| 20241 | 30 slow, each line is parsed every time it is executed. |
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31 |
| 20241 | 32 The main goal of Vim9 script is to drastically improve performance. This is |
| 33 accomplished by compiling commands into instructions that can be efficiently | |
| 34 executed. An increase in execution speed of 10 to 100 times can be expected. | |
| 35 | |
| 36 A secondary goal is to avoid Vim-specific constructs and get closer to | |
| 37 commonly used programming languages, such as JavaScript, TypeScript and Java. | |
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38 |
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39 The performance improvements can only be achieved by not being 100% backwards |
| 20552 | 40 compatible. For example, making function arguments available in the |
| 41 "a:" dictionary adds quite a lot of overhead. In a Vim9 function this | |
| 42 dictionary is not available. Other differences are more subtle, such as how | |
| 43 errors are handled. | |
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44 |
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45 The Vim9 script syntax and semantics are used in: |
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46 - a function defined with the `:def` command |
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47 - a script file where the first command is `vim9script` |
| 22328 | 48 - an autocommand defined in the context of the above |
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49 - a command prefixed with the `vim9cmd` command modifier |
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50 |
| 23573 | 51 When using `:function` in a Vim9 script file the legacy syntax is used, with |
| 52 the highest |scriptversion|. However, this can be confusing and is therefore | |
| 53 discouraged. | |
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54 |
| 20241 | 55 Vim9 script and legacy Vim script can be mixed. There is no requirement to |
| 22328 | 56 rewrite old scripts, they keep working as before. You may want to use a few |
| 57 `:def` functions for code that needs to be fast. | |
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58 |
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59 :vim9[cmd] {cmd} *:vim9* *:vim9cmd* |
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60 Execute {cmd} using Vim9 script syntax and semantics. |
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61 Useful when typing a command and in a legacy script or |
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62 function. |
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63 |
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64 :leg[acy] {cmd} *:leg* *:legacy* |
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65 Execute {cmd} using legacy script syntax and semantics. Only |
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66 useful in a Vim9 script or a :def function. |
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67 Note that {cmd} cannot use local variables, since it is parsed |
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68 with legacy expression syntax. |
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69 |
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70 ============================================================================== |
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71 |
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72 2. Differences from legacy Vim script *vim9-differences* |
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73 |
| 22441 | 74 Overview ~ |
| 75 | |
| 76 Brief summary of the differences you will most often encounter when using Vim9 | |
| 77 script and `:def` functions; details are below: | |
| 78 - Comments start with #, not ": > | |
| 23573 | 79 echo "hello" # comment |
| 22441 | 80 - Using a backslash for line continuation is hardly ever needed: > |
| 23573 | 81 echo "hello " |
| 22441 | 82 .. yourName |
| 83 .. ", how are you?" | |
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84 - White space is required in many places to improve readability. |
| 22441 | 85 - Assign values without `:let`, declare variables with `:var`: > |
| 23573 | 86 var count = 0 |
| 22441 | 87 count += 3 |
| 88 - Constants can be declared with `:final` and `:const`: > | |
| 23573 | 89 final matches = [] # add matches |
| 22441 | 90 const names = ['Betty', 'Peter'] # cannot be changed |
| 91 - `:final` cannot be used as an abbreviation of `:finally`. | |
| 92 - Variables and functions are script-local by default. | |
| 93 - Functions are declared with argument types and return type: > | |
| 94 def CallMe(count: number, message: string): bool | |
| 95 - Call functions without `:call`: > | |
| 23573 | 96 writefile(['done'], 'file.txt') |
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97 - You cannot use old Ex commands `:xit`, `:t`, `:k`, `:append`, `:change`, |
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98 `:insert`, `:open`, and `:s` or `:d` with only flags. |
| 25973 | 99 - You cannot use curly-braces names. |
| 22441 | 100 - A range before a command must be prefixed with a colon: > |
| 23573 | 101 :%s/this/that |
| 25700 | 102 - Executing a register with "@r" does not work, you can prepend a colon or use |
| 103 `:exe`: > | |
| 104 :exe @a | |
| 23573 | 105 - Unless mentioned specifically, the highest |scriptversion| is used. |
| 22441 | 106 |
| 107 | |
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108 Comments starting with # ~ |
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109 |
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110 In legacy Vim script comments start with double quote. In Vim9 script |
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111 comments start with #. > |
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112 # declarations |
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113 var count = 0 # number of occurrences |
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114 |
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115 The reason is that a double quote can also be the start of a string. In many |
| 21825 | 116 places, especially halfway through an expression with a line break, it's hard |
| 117 to tell what the meaning is, since both a string and a comment can be followed | |
| 118 by arbitrary text. To avoid confusion only # comments are recognized. This | |
| 119 is the same as in shell scripts and Python programs. | |
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120 |
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121 In Vi # is a command to list text with numbers. In Vim9 script you can use |
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122 `:number` for that. > |
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123 101 number |
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124 |
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125 To improve readability there must be a space between a command and the # |
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126 that starts a comment: > |
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127 var name = value # comment |
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128 var name = value# error! |
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129 |
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130 Do not start a comment with #{, it looks like the legacy dictionary literal |
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131 and produces an error where this might be confusing. #{{ or #{{{ are OK, |
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132 these can be used to start a fold. |
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133 |
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134 In legacy Vim script # is also used for the alternate file name. In Vim9 |
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135 script you need to use %% instead. Instead of ## use %%% (stands for all |
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136 arguments). |
| 20115 | 137 |
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138 |
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139 Vim9 functions ~ |
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140 |
| 20241 | 141 A function defined with `:def` is compiled. Execution is many times faster, |
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142 often 10 to 100 times. |
| 20241 | 143 |
| 20552 | 144 Many errors are already found when compiling, before the function is executed. |
| 20241 | 145 The syntax is strict, to enforce code that is easy to read and understand. |
| 146 | |
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147 Compilation is done when any of these is encountered: |
| 23164 | 148 - the first time the function is called |
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149 - when the `:defcompile` command is encountered in the script after the |
| 21991 | 150 function was defined |
| 151 - `:disassemble` is used for the function. | |
| 152 - a function that is compiled calls the function or uses it as a function | |
| 25700 | 153 reference (so that the argument and return types can be checked) |
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154 *E1091* |
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155 If compilation fails it is not tried again on the next call, instead this |
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156 error is given: "E1091: Function is not compiled: {name}". |
| 24569 | 157 Compilation will fail when encountering a user command that has not been |
| 158 created yet. In this case you can call `execute()` to invoke it at runtime. > | |
| 159 def MyFunc() | |
| 160 execute('DefinedLater') | |
| 161 enddef | |
| 20552 | 162 |
| 163 `:def` has no options like `:function` does: "range", "abort", "dict" or | |
| 23164 | 164 "closure". A `:def` function always aborts on an error (unless `:silent!` was |
| 26708 | 165 used for the command or the error was caught a `:try` block), does not get a |
| 166 range passed cannot be a "dict" function, and can always be a closure. | |
| 25700 | 167 *vim9-no-dict-function* |
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168 Later classes will be added, which replaces the "dict function" mechanism. |
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169 For now you will need to pass the dictionary explicitly: > |
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170 def DictFunc(d: dict<any>, arg: string) |
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171 echo d[arg] |
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172 enddef |
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173 var d = {item: 'value', func: DictFunc} |
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174 d.func(d, 'item') |
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175 |
| 25836 | 176 You can call a legacy dict function though: > |
| 177 func Legacy() dict | |
| 178 echo self.value | |
| 179 endfunc | |
| 180 def CallLegacy() | |
| 181 var d = {func: Legacy, value: 'text'} | |
| 182 d.func() | |
| 183 enddef | |
| 184 | |
| 20241 | 185 The argument types and return type need to be specified. The "any" type can |
| 186 be used, type checking will then be done at runtime, like with legacy | |
| 187 functions. | |
| 188 | |
| 21825 | 189 Arguments are accessed by name, without "a:", just like any other language. |
| 190 There is no "a:" dictionary or "a:000" list. | |
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191 *vim9-variable-arguments* |
| 20241 | 192 Variable arguments are defined as the last argument, with a name and have a |
| 21825 | 193 list type, similar to TypeScript. For example, a list of numbers: > |
| 22171 | 194 def MyFunc(...itemlist: list<number>) |
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195 for item in itemlist |
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196 ... |
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197 |
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198 When a function argument is optional (it has a default value) passing `v:none` |
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199 as the argument results in using the default value. This is useful when you |
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200 want to specify a value for an argument that comes after an argument that |
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201 should use its default value. Example: > |
| 25973 | 202 def MyFunc(one = 'one', last = 'last') |
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203 ... |
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204 enddef |
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205 MyFunc(v:none, 'LAST') # first argument uses default value 'one' |
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206 < |
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207 *vim9-ignored-argument* |
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208 The argument "_" (an underscore) can be used to ignore the argument. This is |
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209 most useful in callbacks where you don't need it, but do need to give an |
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210 argument to match the call. E.g. when using map() two arguments are passed, |
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211 the key and the value, to ignore the key: > |
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212 map(myList, (_, v) => v * 2) |
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213 There is no error for using the "_" argument multiple times. No type needs to |
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214 be given. |
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215 |
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216 |
| 20241 | 217 Functions and variables are script-local by default ~ |
| 20856 | 218 *vim9-scopes* |
| 20115 | 219 When using `:function` or `:def` to specify a new function at the script level |
| 220 in a Vim9 script, the function is local to the script, as if "s:" was | |
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221 prefixed. Using the "s:" prefix is optional. To define a global function or |
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222 variable the "g:" prefix must be used. For functions in an autoload script |
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223 the "name#" prefix is sufficient. > |
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224 def ThisFunction() # script-local |
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225 def s:ThisFunction() # script-local |
| 22171 | 226 def g:ThatFunction() # global |
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227 def scriptname#function() # autoload |
| 20115 | 228 |
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229 When using `:function` or `:def` to specify a nested function inside a `:def` |
| 26438 | 230 function and no namespace was given, this nested function is local to the code |
| 231 block it is defined in. In a `:def` function it is not possible to define a | |
| 232 script-local function. It is possible to define a global function by using | |
| 233 the "g:" prefix. | |
| 20115 | 234 |
| 235 When referring to a function and no "s:" or "g:" prefix is used, Vim will | |
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236 search for the function: |
| 22565 | 237 - in the function scope, in block scopes |
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238 - in the script scope, possibly imported |
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239 - in the list of global functions |
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240 However, it is recommended to always use "g:" to refer to a global function |
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241 for clarity. |
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242 |
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243 Since a script-local function reference can be used without "s:" the name must |
| 24278 | 244 start with an upper case letter even when using the "s:" prefix. In legacy |
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245 script "s:funcref" could be used, because it could not be referred to with |
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246 "funcref". In Vim9 script it can, therefore "s:Funcref" must be used to avoid |
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247 that the name interferes with builtin functions. |
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248 |
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249 In all cases the function must be defined before used. That is when it is |
| 22723 | 250 called, when `:defcompile` causes it to be compiled, or when code that calls |
| 251 it is being compiled (to figure out the return type). | |
| 20241 | 252 |
| 21676 | 253 The result is that functions and variables without a namespace can usually be |
| 20241 | 254 found in the script, either defined there or imported. Global functions and |
| 21676 | 255 variables could be defined anywhere (good luck finding out where!). |
| 20115 | 256 |
| 21825 | 257 Global functions can still be defined and deleted at nearly any time. In |
| 20317 | 258 Vim9 script script-local functions are defined once when the script is sourced |
| 20552 | 259 and cannot be deleted or replaced. |
| 20115 | 260 |
| 23305 | 261 When compiling a function and a function call is encountered for a function |
| 262 that is not (yet) defined, the |FuncUndefined| autocommand is not triggered. | |
| 263 You can use an autoload function if needed, or call a legacy function and have | |
| 264 |FuncUndefined| triggered there. | |
| 265 | |
| 20115 | 266 |
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267 Reloading a Vim9 script clears functions and variables by default ~ |
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268 *vim9-reload* |
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269 When loading a legacy Vim script a second time nothing is removed, the |
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270 commands will replace existing variables and functions and create new ones. |
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271 |
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272 When loading a Vim9 script a second time all existing script-local functions |
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273 and variables are deleted, thus you start with a clean slate. This is useful |
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274 if you are developing a plugin and want to try a new version. If you renamed |
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275 something you don't have to worry about the old name still hanging around. |
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276 |
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277 If you do want to keep items, use: > |
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278 vim9script noclear |
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279 |
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280 You want to use this in scripts that use a `finish` command to bail out at |
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281 some point when loaded again. E.g. when a buffer local option is set: > |
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282 vim9script noclear |
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283 setlocal completefunc=SomeFunc |
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284 if exists('*g:SomeFunc') | finish | endif |
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285 def g:SomeFunc() |
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286 .... |
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287 |
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288 |
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289 Variable declarations with :var, :final and :const ~ |
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290 *vim9-declaration* *:var* |
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291 Local variables need to be declared with `:var`. Local constants need to be |
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292 declared with `:final` or `:const`. We refer to both as "variables" in this |
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293 section. |
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294 |
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295 Variables can be local to a script, function or code block: > |
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296 vim9script |
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297 var script_var = 123 |
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298 def SomeFunc() |
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299 var func_var = script_var |
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300 if cond |
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301 var block_var = func_var |
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302 ... |
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303 |
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304 The variables are only visible in the block where they are defined and nested |
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305 blocks. Once the block ends the variable is no longer accessible: > |
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306 if cond |
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307 var inner = 5 |
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308 else |
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309 var inner = 0 |
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310 endif |
| 22171 | 311 echo inner # Error! |
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312 |
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313 The declaration must be done earlier: > |
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314 var inner: number |
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315 if cond |
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316 inner = 5 |
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317 else |
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318 inner = 0 |
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319 endif |
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320 echo inner |
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321 |
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322 To intentionally hide a variable from code that follows, a block can be |
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323 used: > |
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324 { |
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325 var temp = 'temp' |
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326 ... |
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327 } |
| 22171 | 328 echo temp # Error! |
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329 |
| 25402 | 330 This is especially useful in a user command: > |
| 331 | |
| 332 command -range Rename { | |
| 25619 | 333 var save = @a |
| 334 @a = 'some expression' | |
| 335 echo 'do something with ' .. @a | |
| 336 @a = save | |
| 337 } | |
| 25402 | 338 |
| 339 And with autocommands: > | |
| 340 | |
| 341 au BufWritePre *.go { | |
| 25619 | 342 var save = winsaveview() |
| 343 silent! exe ':%! some formatting command' | |
| 344 winrestview(save) | |
| 345 } | |
| 25402 | 346 |
| 347 Although using a :def function probably works better. | |
| 348 | |
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349 Declaring a variable with a type but without an initializer will initialize to |
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350 false (for bool), empty (for string, list, dict, etc.) or zero (for number, |
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351 any, etc.). This matters especially when using the "any" type, the value will |
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352 default to the number zero. |
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353 |
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354 In Vim9 script `:let` cannot be used. An existing variable is assigned to |
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355 without any command. The same for global, window, tab, buffer and Vim |
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356 variables, because they are not really declared. Those can also be deleted |
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357 with `:unlet`. |
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358 |
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359 `:lockvar` does not work on local variables. Use `:const` and `:final` |
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360 instead. |
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361 |
| 25619 | 362 The `exists()` and `exists_compiled()` functions do not work on local variables |
| 363 or arguments. | |
| 25402 | 364 |
| 24024 | 365 Variables, functions and function arguments cannot shadow previously defined |
| 366 or imported variables and functions in the same script file. | |
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367 Variables may shadow Ex commands, rename the variable if needed. |
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368 |
| 24387 | 369 Global variables must be prefixed with "g:", also at the script level. > |
| 19968 | 370 vim9script |
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371 var script_local = 'text' |
| 21499 | 372 g:global = 'value' |
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373 var Funcref = g:ThatFunction |
| 19968 | 374 |
| 24387 | 375 Global functions must be prefixed with "g:" when defining them, but can be |
| 376 called without "g:". > | |
| 377 vim9script | |
| 378 def g:GlobalFunc(): string | |
| 379 return 'text' | |
| 380 enddef | |
| 381 echo GlobalFunc() | |
| 382 The "g:" prefix is not needed for auto-load functions. | |
| 383 | |
| 25619 | 384 *vim9-function-defined-later* |
| 385 Although global functions can be called without the "g:" prefix, they must | |
| 386 exist when compiled. By adding the "g:" prefix the function can be defined | |
| 387 later. Example: > | |
| 388 def CallPluginFunc() | |
| 389 if exists('g:loaded_plugin') | |
| 390 g:PluginFunc() | |
| 391 endif | |
| 392 enddef | |
| 393 | |
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394 If you do it like this, you get an error at compile time that "PluginFunc" |
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395 does not exist, even when "g:loaded_plugin" does not exist: > |
| 25619 | 396 def CallPluginFunc() |
| 397 if exists('g:loaded_plugin') | |
| 398 PluginFunc() # Error - function not found | |
| 399 endif | |
| 400 enddef | |
| 401 | |
| 402 You can use exists_compiled() to avoid the error, but then the function would | |
| 403 not be called, even when "g:loaded_plugin" is defined later: > | |
| 404 def CallPluginFunc() | |
| 405 if exists_compiled('g:loaded_plugin') | |
| 406 PluginFunc() # Function may never be called | |
| 407 endif | |
| 408 enddef | |
| 409 | |
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410 Since `&opt = value` is now assigning a value to option "opt", ":&" cannot be |
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411 used to repeat a `:substitute` command. |
| 24468 | 412 *vim9-unpack-ignore* |
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413 For an unpack assignment the underscore can be used to ignore a list item, |
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414 similar to how a function argument can be ignored: > |
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415 [a, _, c] = theList |
| 24468 | 416 To ignore any remaining items: > |
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417 [a, b; _] = longList |
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418 |
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419 Declaring more than one variable at a time, using the unpack notation, is |
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420 possible. Each variable can have a type or infer it from the value: > |
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421 var [v1: number, v2] = GetValues() |
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422 Use this only when there is a list with values, declaring one variable per |
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423 line is much easier to read and change later. |
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424 |
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425 |
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426 Constants ~ |
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427 *vim9-const* *vim9-final* |
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428 How constants work varies between languages. Some consider a variable that |
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429 can't be assigned another value a constant. JavaScript is an example. Others |
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430 also make the value immutable, thus when a constant uses a list, the list |
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431 cannot be changed. In Vim9 we can use both. |
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432 |
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433 `:const` is used for making both the variable and the value a constant. Use |
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434 this for composite structures that you want to make sure will not be modified. |
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435 Example: > |
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436 const myList = [1, 2] |
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437 myList = [3, 4] # Error! |
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438 myList[0] = 9 # Error! |
| 24024 | 439 myList->add(3) # Error! |
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440 < *:final* |
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441 `:final` is used for making only the variable a constant, the value can be |
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442 changed. This is well known from Java. Example: > |
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443 final myList = [1, 2] |
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444 myList = [3, 4] # Error! |
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445 myList[0] = 9 # OK |
| 24024 | 446 myList->add(3) # OK |
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447 |
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448 It is common to write constants as ALL_CAPS, but you don't have to. |
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449 |
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450 The constant only applies to the value itself, not what it refers to. > |
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451 final females = ["Mary"] |
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452 const NAMES = [["John", "Peter"], females] |
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453 NAMES[0] = ["Jack"] # Error! |
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454 NAMES[0][0] = "Jack" # Error! |
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455 NAMES[1] = ["Emma"] # Error! |
| 23573 | 456 NAMES[1][0] = "Emma" # OK, now females[0] == "Emma" |
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457 |
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458 |
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459 Omitting :call and :eval ~ |
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460 |
|
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461 Functions can be called without `:call`: > |
| 22171 | 462 writefile(lines, 'file') |
| 19303 | 463 Using `:call` is still possible, but this is discouraged. |
|
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464 |
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465 A method call without `eval` is possible, so long as the start is an |
|
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466 identifier or can't be an Ex command. For a function either "(" or "->" must |
|
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467 be following, without a line break. Examples: > |
|
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468 myList->add(123) |
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469 g:myList->add(123) |
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470 [1, 2, 3]->Process() |
|
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471 {a: 1, b: 2}->Process() |
|
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472 "foobar"->Process() |
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473 ("foobar")->Process() |
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474 'foobar'->Process() |
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475 ('foobar')->Process() |
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476 |
| 21825 | 477 In the rare case there is ambiguity between a function name and an Ex command, |
| 21676 | 478 prepend ":" to make clear you want to use the Ex command. For example, there |
| 479 is both the `:substitute` command and the `substitute()` function. When the | |
| 480 line starts with `substitute(` this will use the function. Prepend a colon to | |
| 481 use the command instead: > | |
|
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482 :substitute(pattern (replacement ( |
|
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483 |
| 25402 | 484 If the expression starts with "!" this is interpreted as a shell command, not |
| 485 negation of a condition. Thus this is a shell command: > | |
| 486 !shellCommand->something | |
| 25700 | 487 Put the expression in parentheses to use the "!" for negation: > |
| 25402 | 488 (!expression)->Method() |
| 489 | |
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490 Note that while variables need to be defined before they can be used, |
| 21825 | 491 functions can be called before being defined. This is required to allow |
| 492 for cyclic dependencies between functions. It is slightly less efficient, | |
|
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493 since the function has to be looked up by name. And a typo in the function |
|
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494 name will only be found when the function is called. |
|
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495 |
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496 |
| 19968 | 497 Omitting function() ~ |
| 498 | |
| 499 A user defined function can be used as a function reference in an expression | |
| 500 without `function()`. The argument types and return type will then be checked. | |
| 501 The function must already have been defined. > | |
| 502 | |
|
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503 var Funcref = MyFunction |
| 19968 | 504 |
| 505 When using `function()` the resulting type is "func", a function with any | |
| 25161 | 506 number of arguments and any return type (including void). The function can be |
| 26708 | 507 defined later if the argument is in quotes. |
| 19968 | 508 |
| 509 | |
|
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510 Lambda using => instead of -> ~ |
| 24387 | 511 *vim9-lambda* |
|
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512 In legacy script there can be confusion between using "->" for a method call |
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513 and for a lambda. Also, when a "{" is found the parser needs to figure out if |
|
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514 it is the start of a lambda or a dictionary, which is now more complicated |
|
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515 because of the use of argument types. |
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516 |
|
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517 To avoid these problems Vim9 script uses a different syntax for a lambda, |
|
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518 which is similar to JavaScript: > |
|
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519 var Lambda = (arg) => expression |
|
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520 |
|
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521 No line break is allowed in the arguments of a lambda up to and including the |
| 25056 | 522 "=>" (so that Vim can tell the difference between an expression in parentheses |
| 24911 | 523 and lambda arguments). This is OK: > |
|
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524 filter(list, (k, v) => |
|
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525 v > 0) |
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526 This does not work: > |
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527 filter(list, (k, v) |
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528 => v > 0) |
|
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529 This also does not work: > |
|
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530 filter(list, (k, |
|
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531 v) => v > 0) |
|
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532 But you can use a backslash to concatenate the lines before parsing: > |
|
517fca70e084
patch 8.2.2239: Vim9: concatenating lines with backslash is inconvenient
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533 filter(list, (k, |
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534 \ v) |
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535 \ => v > 0) |
|
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536 < *vim9-lambda-arguments* |
|
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537 In legacy script a lambda could be called with any number of extra arguments, |
|
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538 there was no way to warn for not using them. In Vim9 script the number of |
|
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539 arguments must match. If you do want to accept any arguments, or any further |
|
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540 arguments, use "..._", which makes the function accept |
|
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541 |vim9-variable-arguments|. Example: > |
|
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patch 8.2.2744: Vim9: no way to explicitly ignore an argument
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542 var Callback = (..._) => 'anything' |
|
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543 echo Callback(1, 2, 3) # displays "anything" |
|
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544 |
| 24387 | 545 < *inline-function* |
|
23318
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|
546 Additionally, a lambda can contain statements in {}: > |
|
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|
547 var Lambda = (arg) => { |
|
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|
548 g:was_called = 'yes' |
|
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|
549 return expression |
|
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550 } |
| 24387 | 551 This can be useful for a timer, for example: > |
| 552 var count = 0 | |
| 553 var timer = timer_start(500, (_) => { | |
| 554 count += 1 | |
| 555 echom 'Handler called ' .. count | |
| 556 }, {repeat: 3}) | |
| 557 | |
|
24272
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diff
changeset
|
558 The ending "}" must be at the start of a line. It can be followed by other |
|
cabed216cc2f
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|
559 characters, e.g.: > |
|
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patch 8.2.2677: Vim9: cannot use only some of the default arguments
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560 var d = mapnew(dict, (k, v): string => { |
|
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patch 8.2.2677: Vim9: cannot use only some of the default arguments
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561 return 'value' |
|
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562 }) |
|
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patch 8.2.2677: Vim9: cannot use only some of the default arguments
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|
563 No command can follow the "{", only a comment can be used there. |
|
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564 |
|
26612
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|
565 *command-block* |
|
2586659245db
patch 8.2.3835: the inline-function example does not work
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|
566 The block can also be used for defining a user command. Inside the block Vim9 |
|
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patch 8.2.3835: the inline-function example does not work
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|
567 syntax will be used. |
|
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|
568 |
| 26591 | 569 If the statements include a dictionary, its closing bracket must not be |
| 570 written at the start of a line. Otherwise, it would be parsed as the end of | |
| 571 the block. This does not work: > | |
| 572 command NewCommand { | |
|
26612
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|
573 g:mydict = { |
| 26591 | 574 'key': 'value', |
| 575 } # ERROR: will be recognized as the end of the block | |
| 576 } | |
| 577 Put the '}' after the last item to avoid this: > | |
| 578 command NewCommand { | |
|
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579 g:mydict = { |
| 26591 | 580 'key': 'value' } |
| 581 } | |
| 582 | |
|
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|
583 Rationale: The "}" cannot be after a command because it would require parsing |
|
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|
584 the commands to find it. For consistency with that no command can follow the |
|
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585 "{". Unfortunately this means using "() => { command }" does not work, line |
|
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|
586 breaks are always required. |
|
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587 |
| 23737 | 588 *vim9-curly* |
|
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589 To avoid the "{" of a dictionary literal to be recognized as a statement block |
| 24024 | 590 wrap it in parentheses: > |
|
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591 var Lambda = (arg) => ({key: 42}) |
|
23318
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|
592 |
| 23737 | 593 Also when confused with the start of a command block: > |
| 594 ({ | |
| 595 key: value | |
| 596 })->method() | |
| 597 | |
|
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Bram Moolenaar <Bram@vim.org>
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598 |
|
19999
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patch 8.2.0555: Vim9: line continuation is not always needed
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|
599 Automatic line continuation ~ |
|
26769
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patch 8.2.3913: help for expressions does not mention Vim9 syntax
Bram Moolenaar <Bram@vim.org>
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changeset
|
600 *vim9-line-continuation* |
|
19999
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patch 8.2.0555: Vim9: line continuation is not always needed
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601 In many cases it is obvious that an expression continues on the next line. In |
|
23392
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Bram Moolenaar <Bram@vim.org>
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|
602 those cases there is no need to prefix the line with a backslash (see |
|
517fca70e084
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changeset
|
603 |line-continuation|). For example, when a list spans multiple lines: > |
|
22391
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patch 8.2.1744: Vim9: using ":const!" is weird
Bram Moolenaar <Bram@vim.org>
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changeset
|
604 var mylist = [ |
|
19999
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patch 8.2.0555: Vim9: line continuation is not always needed
Bram Moolenaar <Bram@vim.org>
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changeset
|
605 'one', |
|
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patch 8.2.0555: Vim9: line continuation is not always needed
Bram Moolenaar <Bram@vim.org>
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|
606 'two', |
|
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|
607 ] |
|
20011
628011800942
patch 8.2.0561: Vim9: cannot split function call in multiple lines
Bram Moolenaar <Bram@vim.org>
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|
608 And when a dict spans multiple lines: > |
|
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patch 8.2.2015: Vim9: literal dict #{} is not like any other language
Bram Moolenaar <Bram@vim.org>
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|
609 var mydict = { |
|
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patch 8.2.0561: Vim9: cannot split function call in multiple lines
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|
610 one: 1, |
|
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patch 8.2.0561: Vim9: cannot split function call in multiple lines
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|
611 two: 2, |
|
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patch 8.2.0561: Vim9: cannot split function call in multiple lines
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612 } |
|
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patch 8.2.2982: Vim9: future commands are not reserved yet
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|
613 With a function call: > |
|
22391
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|
614 var result = Func( |
|
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patch 8.2.0561: Vim9: cannot split function call in multiple lines
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|
615 arg1, |
|
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patch 8.2.0561: Vim9: cannot split function call in multiple lines
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|
616 arg2 |
|
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617 ) |
|
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|
618 |
|
20982
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patch 8.2.1042: Vim9: cannot put an operator on the next line
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|
619 For binary operators in expressions not in [], {} or () a line break is |
|
bb49b5090a9c
patch 8.2.1042: Vim9: cannot put an operator on the next line
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parents:
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|
620 possible just before or after the operator. For example: > |
|
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patch 8.2.1744: Vim9: using ":const!" is weird
Bram Moolenaar <Bram@vim.org>
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|
621 var text = lead |
|
20982
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patch 8.2.1042: Vim9: cannot put an operator on the next line
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|
622 .. middle |
|
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patch 8.2.1042: Vim9: cannot put an operator on the next line
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623 .. end |
|
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patch 8.2.1744: Vim9: using ":const!" is weird
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|
624 var total = start + |
| 23573 | 625 end - |
|
20013
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patch 8.2.0562: Vim9: cannot split an expression into multiple lines
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|
626 correction |
|
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627 var result = positive |
|
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patch 8.2.1042: Vim9: cannot put an operator on the next line
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|
628 ? PosFunc(arg) |
|
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patch 8.2.1042: Vim9: cannot put an operator on the next line
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|
629 : NegFunc(arg) |
|
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patch 8.2.0562: Vim9: cannot split an expression into multiple lines
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|
630 |
| 21499 | 631 For a method call using "->" and a member using a dot, a line break is allowed |
| 632 before it: > | |
|
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|
633 var result = GetBuilder() |
| 20965 | 634 ->BuilderSetWidth(333) |
| 635 ->BuilderSetHeight(777) | |
| 636 ->BuilderBuild() | |
|
22391
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|
637 var result = MyDict |
| 21499 | 638 .member |
| 20965 | 639 |
|
23392
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patch 8.2.2239: Vim9: concatenating lines with backslash is inconvenient
Bram Moolenaar <Bram@vim.org>
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|
640 For commands that have an argument that is a list of commands, the | character |
|
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patch 8.2.2239: Vim9: concatenating lines with backslash is inconvenient
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|
641 at the start of the line indicates line continuation: > |
|
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patch 8.2.2239: Vim9: concatenating lines with backslash is inconvenient
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|
642 autocmd BufNewFile *.match if condition |
|
517fca70e084
patch 8.2.2239: Vim9: concatenating lines with backslash is inconvenient
Bram Moolenaar <Bram@vim.org>
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|
643 | echo 'match' |
|
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patch 8.2.2239: Vim9: concatenating lines with backslash is inconvenient
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644 | endif |
|
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patch 8.2.2239: Vim9: concatenating lines with backslash is inconvenient
Bram Moolenaar <Bram@vim.org>
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changeset
|
645 |
| 25973 | 646 Note that this means that in heredoc the first line cannot start with a bar: > |
|
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patch 8.2.2982: Vim9: future commands are not reserved yet
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|
647 var lines =<< trim END |
|
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patch 8.2.2982: Vim9: future commands are not reserved yet
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changeset
|
648 | this doesn't work |
|
b6ac4ed5e2d2
patch 8.2.2982: Vim9: future commands are not reserved yet
Bram Moolenaar <Bram@vim.org>
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|
649 END |
|
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patch 8.2.2982: Vim9: future commands are not reserved yet
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diff
changeset
|
650 Either use an empty line at the start or do not use heredoc. Or temporarily |
|
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patch 8.2.2982: Vim9: future commands are not reserved yet
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changeset
|
651 add the "C" flag to 'cpoptions': > |
|
b6ac4ed5e2d2
patch 8.2.2982: Vim9: future commands are not reserved yet
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|
652 set cpo+=C |
|
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patch 8.2.2982: Vim9: future commands are not reserved yet
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changeset
|
653 var lines =<< trim END |
| 25973 | 654 | this works |
|
24888
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655 END |
|
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patch 8.2.2982: Vim9: future commands are not reserved yet
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|
656 set cpo-=C |
|
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changeset
|
657 If the heredoc is inside a function 'cpoptions' must be set before :def and |
|
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patch 8.2.2982: Vim9: future commands are not reserved yet
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|
658 restored after the :enddef. |
|
b6ac4ed5e2d2
patch 8.2.2982: Vim9: future commands are not reserved yet
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|
659 |
|
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patch 8.2.2982: Vim9: future commands are not reserved yet
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660 In places where line continuation with a backslash is still needed, such as |
| 25161 | 661 splitting up a long Ex command, comments can start with '#\ ': > |
| 662 syn region Text | |
|
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patch 8.2.2982: Vim9: future commands are not reserved yet
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|
663 \ start='foo' |
|
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664 #\ comment |
|
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|
665 \ end='bar' |
| 25161 | 666 Like with legacy script '"\ ' is used. This is also needed when line |
| 667 continuation is used without a backslash and a line starts with a bar: > | |
| 668 au CursorHold * echom 'BEFORE bar' | |
| 669 #\ some comment | |
| 670 | echom 'AFTER bar' | |
| 671 < | |
| 672 *E1050* | |
|
20982
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changeset
|
673 To make it possible for the operator at the start of the line to be |
|
24888
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|
674 recognized, it is required to put a colon before a range. This example will |
|
b6ac4ed5e2d2
patch 8.2.2982: Vim9: future commands are not reserved yet
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changeset
|
675 add "start" and print: > |
|
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|
676 var result = start |
|
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|
677 + print |
| 21250 | 678 Like this: > |
|
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|
679 var result = start + print |
| 21250 | 680 |
|
20982
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patch 8.2.1042: Vim9: cannot put an operator on the next line
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changeset
|
681 This will assign "start" and print a line: > |
|
22391
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|
682 var result = start |
|
20982
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patch 8.2.1042: Vim9: cannot put an operator on the next line
Bram Moolenaar <Bram@vim.org>
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changeset
|
683 :+ print |
|
19999
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patch 8.2.0555: Vim9: line continuation is not always needed
Bram Moolenaar <Bram@vim.org>
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changeset
|
684 |
| 23047 | 685 Note that the colon is not required for the |+cmd| argument: > |
| 686 edit +6 fname | |
| 687 | |
|
20015
c001ee73519a
patch 8.2.0563: Vim9: cannot split a function line
Bram Moolenaar <Bram@vim.org>
parents:
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diff
changeset
|
688 It is also possible to split a function header over multiple lines, in between |
|
c001ee73519a
patch 8.2.0563: Vim9: cannot split a function line
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diff
changeset
|
689 arguments: > |
|
c001ee73519a
patch 8.2.0563: Vim9: cannot split a function line
Bram Moolenaar <Bram@vim.org>
parents:
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diff
changeset
|
690 def MyFunc( |
|
c001ee73519a
patch 8.2.0563: Vim9: cannot split a function line
Bram Moolenaar <Bram@vim.org>
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changeset
|
691 text: string, |
|
c001ee73519a
patch 8.2.0563: Vim9: cannot split a function line
Bram Moolenaar <Bram@vim.org>
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changeset
|
692 separator = '-' |
|
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patch 8.2.0563: Vim9: cannot split a function line
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changeset
|
693 ): string |
|
c001ee73519a
patch 8.2.0563: Vim9: cannot split a function line
Bram Moolenaar <Bram@vim.org>
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changeset
|
694 |
| 23305 | 695 Since a continuation line cannot be easily recognized the parsing of commands |
|
23318
c76240efdf02
patch 8.2.2204: Vim9: using -> both for method and lambda is confusing
Bram Moolenaar <Bram@vim.org>
parents:
23305
diff
changeset
|
696 has been made stricter. E.g., because of the error in the first line, the |
| 23305 | 697 second line is seen as a separate command: > |
| 698 popup_create(some invalid expression, { | |
| 699 exit_cb: Func}) | |
| 700 Now "exit_cb: Func})" is actually a valid command: save any changes to the | |
| 701 file "_cb: Func})" and exit. To avoid this kind of mistake in Vim9 script | |
| 702 there must be white space between most command names and the argument. | |
| 703 | |
| 23666 | 704 However, the argument of a command that is a command won't be recognized. For |
| 705 example, after "windo echo expr" a line break inside "expr" will not be seen. | |
| 706 | |
| 23305 | 707 |
| 21250 | 708 Notes: |
| 709 - "enddef" cannot be used at the start of a continuation line, it ends the | |
| 710 current function. | |
| 711 - No line break is allowed in the LHS of an assignment. Specifically when | |
| 712 unpacking a list |:let-unpack|. This is OK: > | |
| 22171 | 713 [var1, var2] = |
| 21250 | 714 Func() |
| 715 < This does not work: > | |
| 22171 | 716 [var1, |
| 21250 | 717 var2] = |
| 718 Func() | |
| 719 - No line break is allowed in between arguments of an `:echo`, `:execute` and | |
| 720 similar commands. This is OK: > | |
| 22171 | 721 echo [1, |
| 21250 | 722 2] [3, |
| 723 4] | |
| 724 < This does not work: > | |
| 22171 | 725 echo [1, 2] |
| 21250 | 726 [3, 4] |
|
24888
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patch 8.2.2982: Vim9: future commands are not reserved yet
Bram Moolenaar <Bram@vim.org>
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diff
changeset
|
727 - In some cases it is difficult for Vim to parse a command, especially when |
|
b6ac4ed5e2d2
patch 8.2.2982: Vim9: future commands are not reserved yet
Bram Moolenaar <Bram@vim.org>
parents:
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diff
changeset
|
728 commands are used as an argument to another command, such as `windo`. In |
|
b6ac4ed5e2d2
patch 8.2.2982: Vim9: future commands are not reserved yet
Bram Moolenaar <Bram@vim.org>
parents:
24751
diff
changeset
|
729 those cases the line continuation with a backslash has to be used. |
|
19999
844c7646f61b
patch 8.2.0555: Vim9: line continuation is not always needed
Bram Moolenaar <Bram@vim.org>
parents:
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changeset
|
730 |
| 24569 | 731 |
| 732 White space ~ | |
| 733 | |
| 734 Vim9 script enforces proper use of white space. This is no longer allowed: > | |
| 735 var name=234 # Error! | |
| 736 var name= 234 # Error! | |
| 737 var name =234 # Error! | |
| 738 There must be white space before and after the "=": > | |
| 739 var name = 234 # OK | |
| 740 White space must also be put before the # that starts a comment after a | |
| 741 command: > | |
| 742 var name = 234# Error! | |
| 743 var name = 234 # OK | |
| 744 | |
| 745 White space is required around most operators. | |
| 746 | |
| 747 White space is required in a sublist (list slice) around the ":", except at | |
| 748 the start and end: > | |
| 749 otherlist = mylist[v : count] # v:count has a different meaning | |
| 750 otherlist = mylist[:] # make a copy of the List | |
| 751 otherlist = mylist[v :] | |
| 752 otherlist = mylist[: v] | |
| 753 | |
| 754 White space is not allowed: | |
| 755 - Between a function name and the "(": > | |
| 756 Func (arg) # Error! | |
| 757 Func | |
| 758 \ (arg) # Error! | |
| 759 Func | |
| 760 (arg) # Error! | |
| 761 Func(arg) # OK | |
| 762 Func( | |
| 763 arg) # OK | |
| 764 Func( | |
| 765 arg # OK | |
| 766 ) | |
| 767 | |
| 25700 | 768 White space is not allowed in a `:set` command between the option name and a |
| 769 following "&", "!", "<", "=", "+=", "-=" or "^=". | |
| 25402 | 770 |
| 24569 | 771 |
|
19181
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patch 8.2.0149: maintaining a Vim9 branch separately is more work
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
772 No curly braces expansion ~ |
|
94eda51ba9ba
patch 8.2.0149: maintaining a Vim9 branch separately is more work
Bram Moolenaar <Bram@vim.org>
parents:
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changeset
|
773 |
|
94eda51ba9ba
patch 8.2.0149: maintaining a Vim9 branch separately is more work
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
774 |curly-braces-names| cannot be used. |
|
94eda51ba9ba
patch 8.2.0149: maintaining a Vim9 branch separately is more work
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
775 |
|
94eda51ba9ba
patch 8.2.0149: maintaining a Vim9 branch separately is more work
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
776 |
|
22936
00b0275ffe7f
patch 8.2.2015: Vim9: literal dict #{} is not like any other language
Bram Moolenaar <Bram@vim.org>
parents:
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diff
changeset
|
777 Dictionary literals ~ |
|
26769
30972227ac8d
patch 8.2.3913: help for expressions does not mention Vim9 syntax
Bram Moolenaar <Bram@vim.org>
parents:
26755
diff
changeset
|
778 *vim9-literal-dict* |
|
22936
00b0275ffe7f
patch 8.2.2015: Vim9: literal dict #{} is not like any other language
Bram Moolenaar <Bram@vim.org>
parents:
22723
diff
changeset
|
779 Traditionally Vim has supported dictionary literals with a {} syntax: > |
|
00b0275ffe7f
patch 8.2.2015: Vim9: literal dict #{} is not like any other language
Bram Moolenaar <Bram@vim.org>
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diff
changeset
|
780 let dict = {'key': value} |
|
00b0275ffe7f
patch 8.2.2015: Vim9: literal dict #{} is not like any other language
Bram Moolenaar <Bram@vim.org>
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diff
changeset
|
781 |
|
23088
285cde4b8d0e
patch 8.2.2090: Vim9: dict does not accept a key in quotes
Bram Moolenaar <Bram@vim.org>
parents:
23047
diff
changeset
|
782 Later it became clear that using a simple text key is very common, thus |
|
285cde4b8d0e
patch 8.2.2090: Vim9: dict does not accept a key in quotes
Bram Moolenaar <Bram@vim.org>
parents:
23047
diff
changeset
|
783 literal dictionaries were introduced in a backwards compatible way: > |
|
22936
00b0275ffe7f
patch 8.2.2015: Vim9: literal dict #{} is not like any other language
Bram Moolenaar <Bram@vim.org>
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diff
changeset
|
784 let dict = #{key: value} |
|
00b0275ffe7f
patch 8.2.2015: Vim9: literal dict #{} is not like any other language
Bram Moolenaar <Bram@vim.org>
parents:
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diff
changeset
|
785 |
|
23088
285cde4b8d0e
patch 8.2.2090: Vim9: dict does not accept a key in quotes
Bram Moolenaar <Bram@vim.org>
parents:
23047
diff
changeset
|
786 However, this #{} syntax is unlike any existing language. As it turns out |
|
285cde4b8d0e
patch 8.2.2090: Vim9: dict does not accept a key in quotes
Bram Moolenaar <Bram@vim.org>
parents:
23047
diff
changeset
|
787 that using a literal key is much more common than using an expression, and |
|
22936
00b0275ffe7f
patch 8.2.2015: Vim9: literal dict #{} is not like any other language
Bram Moolenaar <Bram@vim.org>
parents:
22723
diff
changeset
|
788 considering that JavaScript uses this syntax, using the {} form for dictionary |
|
23088
285cde4b8d0e
patch 8.2.2090: Vim9: dict does not accept a key in quotes
Bram Moolenaar <Bram@vim.org>
parents:
23047
diff
changeset
|
789 literals is considered a much more useful syntax. In Vim9 script the {} form |
|
22936
00b0275ffe7f
patch 8.2.2015: Vim9: literal dict #{} is not like any other language
Bram Moolenaar <Bram@vim.org>
parents:
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diff
changeset
|
790 uses literal keys: > |
| 23666 | 791 var dict = {key: value} |
|
22936
00b0275ffe7f
patch 8.2.2015: Vim9: literal dict #{} is not like any other language
Bram Moolenaar <Bram@vim.org>
parents:
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diff
changeset
|
792 |
|
23088
285cde4b8d0e
patch 8.2.2090: Vim9: dict does not accept a key in quotes
Bram Moolenaar <Bram@vim.org>
parents:
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diff
changeset
|
793 This works for alphanumeric characters, underscore and dash. If you want to |
|
285cde4b8d0e
patch 8.2.2090: Vim9: dict does not accept a key in quotes
Bram Moolenaar <Bram@vim.org>
parents:
23047
diff
changeset
|
794 use another character, use a single or double quoted string: > |
| 23666 | 795 var dict = {'key with space': value} |
| 796 var dict = {"key\twith\ttabs": value} | |
| 797 var dict = {'': value} # empty key | |
|
23088
285cde4b8d0e
patch 8.2.2090: Vim9: dict does not accept a key in quotes
Bram Moolenaar <Bram@vim.org>
parents:
23047
diff
changeset
|
798 |
|
285cde4b8d0e
patch 8.2.2090: Vim9: dict does not accept a key in quotes
Bram Moolenaar <Bram@vim.org>
parents:
23047
diff
changeset
|
799 In case the key needs to be an expression, square brackets can be used, just |
|
285cde4b8d0e
patch 8.2.2090: Vim9: dict does not accept a key in quotes
Bram Moolenaar <Bram@vim.org>
parents:
23047
diff
changeset
|
800 like in JavaScript: > |
| 23666 | 801 var dict = {["key" .. nr]: value} |
|
22936
00b0275ffe7f
patch 8.2.2015: Vim9: literal dict #{} is not like any other language
Bram Moolenaar <Bram@vim.org>
parents:
22723
diff
changeset
|
802 |
|
23827
7e0d8f1cae7d
patch 8.2.2455: Vim9: key type for literal dict and indexing is inconsistent
Bram Moolenaar <Bram@vim.org>
parents:
23737
diff
changeset
|
803 The key type can be string, number, bool or float. Other types result in an |
|
7e0d8f1cae7d
patch 8.2.2455: Vim9: key type for literal dict and indexing is inconsistent
Bram Moolenaar <Bram@vim.org>
parents:
23737
diff
changeset
|
804 error. A number can be given with and without the []: > |
|
7e0d8f1cae7d
patch 8.2.2455: Vim9: key type for literal dict and indexing is inconsistent
Bram Moolenaar <Bram@vim.org>
parents:
23737
diff
changeset
|
805 var dict = {123: 'without', [456]: 'with'} |
|
7e0d8f1cae7d
patch 8.2.2455: Vim9: key type for literal dict and indexing is inconsistent
Bram Moolenaar <Bram@vim.org>
parents:
23737
diff
changeset
|
806 echo dict |
|
7e0d8f1cae7d
patch 8.2.2455: Vim9: key type for literal dict and indexing is inconsistent
Bram Moolenaar <Bram@vim.org>
parents:
23737
diff
changeset
|
807 {'456': 'with', '123': 'without'} |
|
7e0d8f1cae7d
patch 8.2.2455: Vim9: key type for literal dict and indexing is inconsistent
Bram Moolenaar <Bram@vim.org>
parents:
23737
diff
changeset
|
808 |
|
22936
00b0275ffe7f
patch 8.2.2015: Vim9: literal dict #{} is not like any other language
Bram Moolenaar <Bram@vim.org>
parents:
22723
diff
changeset
|
809 |
|
23978
54b2aa1f0d42
patch 8.2.2531: Vim9: the :k command is obscure
Bram Moolenaar <Bram@vim.org>
parents:
23974
diff
changeset
|
810 No :xit, :t, :k, :append, :change or :insert ~ |
| 19303 | 811 |
|
21584
d0c76ce48326
patch 8.2.1342: Vim9: accidentally using "t" gives a confusing error
Bram Moolenaar <Bram@vim.org>
parents:
21550
diff
changeset
|
812 These commands are too easily confused with local variable names. |
|
d0c76ce48326
patch 8.2.1342: Vim9: accidentally using "t" gives a confusing error
Bram Moolenaar <Bram@vim.org>
parents:
21550
diff
changeset
|
813 Instead of `:x` or `:xit` you can use `:exit`. |
|
d0c76ce48326
patch 8.2.1342: Vim9: accidentally using "t" gives a confusing error
Bram Moolenaar <Bram@vim.org>
parents:
21550
diff
changeset
|
814 Instead of `:t` you can use `:copy`. |
|
23978
54b2aa1f0d42
patch 8.2.2531: Vim9: the :k command is obscure
Bram Moolenaar <Bram@vim.org>
parents:
23974
diff
changeset
|
815 Instead of `:k` you can use `:mark`. |
|
19181
94eda51ba9ba
patch 8.2.0149: maintaining a Vim9 branch separately is more work
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
816 |
| 19303 | 817 |
| 818 Comparators ~ | |
| 819 | |
| 820 The 'ignorecase' option is not used for comparators that use strings. | |
|
19181
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patch 8.2.0149: maintaining a Vim9 branch separately is more work
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
821 |
|
94eda51ba9ba
patch 8.2.0149: maintaining a Vim9 branch separately is more work
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
822 |
| 24569 | 823 Abort after error ~ |
| 824 | |
| 825 In legacy script, when an error is encountered, Vim continues to execute | |
| 826 following lines. This can lead to a long sequence of errors and need to type | |
| 827 CTRL-C to stop it. In Vim9 script execution of commands stops at the first | |
| 828 error. Example: > | |
| 829 vim9script | |
| 830 var x = does-not-exist | |
| 831 echo 'not executed' | |
| 832 | |
| 833 | |
| 23666 | 834 For loop ~ |
| 835 | |
| 26438 | 836 The loop variable must not be declared yet: > |
| 26304 | 837 var i = 1 |
| 838 for i in [1, 2, 3] # Error! | |
| 839 | |
| 26438 | 840 It is possible to use a global variable though: > |
| 841 g:i = 1 | |
| 842 for g:i in [1, 2, 3] | |
| 843 echo g:i | |
| 844 endfor | |
| 845 | |
| 23666 | 846 Legacy Vim script has some tricks to make a for loop over a list handle |
| 847 deleting items at the current or previous item. In Vim9 script it just uses | |
| 848 the index, if items are deleted then items in the list will be skipped. | |
| 849 Example legacy script: > | |
| 850 let l = [1, 2, 3, 4] | |
| 851 for i in l | |
| 852 echo i | |
| 853 call remove(l, index(l, i)) | |
| 854 endfor | |
| 855 Would echo: | |
| 856 1 | |
| 857 2 | |
| 858 3 | |
| 859 4 | |
| 860 In compiled Vim9 script you get: | |
| 861 1 | |
| 862 3 | |
| 863 Generally, you should not change the list that is iterated over. Make a copy | |
| 864 first if needed. | |
| 865 | |
| 866 | |
|
19181
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patch 8.2.0149: maintaining a Vim9 branch separately is more work
Bram Moolenaar <Bram@vim.org>
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changeset
|
867 Conditions and expressions ~ |
|
26769
30972227ac8d
patch 8.2.3913: help for expressions does not mention Vim9 syntax
Bram Moolenaar <Bram@vim.org>
parents:
26755
diff
changeset
|
868 *vim9-boolean* |
|
22500
ef8a3177edc1
patch 8.2.1798: Vim9: trinary operator condition is too permissive
Bram Moolenaar <Bram@vim.org>
parents:
22494
diff
changeset
|
869 Conditions and expressions are mostly working like they do in other languages. |
|
ef8a3177edc1
patch 8.2.1798: Vim9: trinary operator condition is too permissive
Bram Moolenaar <Bram@vim.org>
parents:
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changeset
|
870 Some values are different from legacy Vim script: |
|
ef8a3177edc1
patch 8.2.1798: Vim9: trinary operator condition is too permissive
Bram Moolenaar <Bram@vim.org>
parents:
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diff
changeset
|
871 value legacy Vim script Vim9 script ~ |
|
ef8a3177edc1
patch 8.2.1798: Vim9: trinary operator condition is too permissive
Bram Moolenaar <Bram@vim.org>
parents:
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changeset
|
872 0 falsy falsy |
|
ef8a3177edc1
patch 8.2.1798: Vim9: trinary operator condition is too permissive
Bram Moolenaar <Bram@vim.org>
parents:
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diff
changeset
|
873 1 truthy truthy |
|
ef8a3177edc1
patch 8.2.1798: Vim9: trinary operator condition is too permissive
Bram Moolenaar <Bram@vim.org>
parents:
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changeset
|
874 99 truthy Error! |
|
ef8a3177edc1
patch 8.2.1798: Vim9: trinary operator condition is too permissive
Bram Moolenaar <Bram@vim.org>
parents:
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diff
changeset
|
875 "0" falsy Error! |
|
ef8a3177edc1
patch 8.2.1798: Vim9: trinary operator condition is too permissive
Bram Moolenaar <Bram@vim.org>
parents:
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diff
changeset
|
876 "99" truthy Error! |
|
ef8a3177edc1
patch 8.2.1798: Vim9: trinary operator condition is too permissive
Bram Moolenaar <Bram@vim.org>
parents:
22494
diff
changeset
|
877 "text" falsy Error! |
|
19181
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patch 8.2.0149: maintaining a Vim9 branch separately is more work
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
878 |
|
22500
ef8a3177edc1
patch 8.2.1798: Vim9: trinary operator condition is too permissive
Bram Moolenaar <Bram@vim.org>
parents:
22494
diff
changeset
|
879 For the "??" operator and when using "!" then there is no error, every value |
|
ef8a3177edc1
patch 8.2.1798: Vim9: trinary operator condition is too permissive
Bram Moolenaar <Bram@vim.org>
parents:
22494
diff
changeset
|
880 is either falsy or truthy. This is mostly like JavaScript, except that an |
|
ef8a3177edc1
patch 8.2.1798: Vim9: trinary operator condition is too permissive
Bram Moolenaar <Bram@vim.org>
parents:
22494
diff
changeset
|
881 empty list and dict is falsy: |
|
ef8a3177edc1
patch 8.2.1798: Vim9: trinary operator condition is too permissive
Bram Moolenaar <Bram@vim.org>
parents:
22494
diff
changeset
|
882 |
|
ef8a3177edc1
patch 8.2.1798: Vim9: trinary operator condition is too permissive
Bram Moolenaar <Bram@vim.org>
parents:
22494
diff
changeset
|
883 type truthy when ~ |
| 23466 | 884 bool true, v:true or 1 |
|
19181
94eda51ba9ba
patch 8.2.0149: maintaining a Vim9 branch separately is more work
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
885 number non-zero |
|
94eda51ba9ba
patch 8.2.0149: maintaining a Vim9 branch separately is more work
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
886 float non-zero |
|
94eda51ba9ba
patch 8.2.0149: maintaining a Vim9 branch separately is more work
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
887 string non-empty |
|
94eda51ba9ba
patch 8.2.0149: maintaining a Vim9 branch separately is more work
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
888 blob non-empty |
|
94eda51ba9ba
patch 8.2.0149: maintaining a Vim9 branch separately is more work
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
889 list non-empty (different from JavaScript) |
|
94eda51ba9ba
patch 8.2.0149: maintaining a Vim9 branch separately is more work
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
890 dictionary non-empty (different from JavaScript) |
| 19968 | 891 func when there is a function name |
| 23466 | 892 special true or v:true |
|
19181
94eda51ba9ba
patch 8.2.0149: maintaining a Vim9 branch separately is more work
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
893 job when not NULL |
|
94eda51ba9ba
patch 8.2.0149: maintaining a Vim9 branch separately is more work
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
894 channel when not NULL |
|
94eda51ba9ba
patch 8.2.0149: maintaining a Vim9 branch separately is more work
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
895 class when not NULL |
| 23466 | 896 object when not NULL (TODO: when isTrue() returns true) |
|
19181
94eda51ba9ba
patch 8.2.0149: maintaining a Vim9 branch separately is more work
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
897 |
|
22494
4c21f7f6f9e3
patch 8.2.1795: Vim9: operators && and || have a confusing result
Bram Moolenaar <Bram@vim.org>
parents:
22441
diff
changeset
|
898 The boolean operators "||" and "&&" expect the values to be boolean, zero or |
|
4c21f7f6f9e3
patch 8.2.1795: Vim9: operators && and || have a confusing result
Bram Moolenaar <Bram@vim.org>
parents:
22441
diff
changeset
|
899 one: > |
|
4c21f7f6f9e3
patch 8.2.1795: Vim9: operators && and || have a confusing result
Bram Moolenaar <Bram@vim.org>
parents:
22441
diff
changeset
|
900 1 || false == true |
|
4c21f7f6f9e3
patch 8.2.1795: Vim9: operators && and || have a confusing result
Bram Moolenaar <Bram@vim.org>
parents:
22441
diff
changeset
|
901 0 || 1 == true |
|
4c21f7f6f9e3
patch 8.2.1795: Vim9: operators && and || have a confusing result
Bram Moolenaar <Bram@vim.org>
parents:
22441
diff
changeset
|
902 0 || false == false |
|
4c21f7f6f9e3
patch 8.2.1795: Vim9: operators && and || have a confusing result
Bram Moolenaar <Bram@vim.org>
parents:
22441
diff
changeset
|
903 1 && true == true |
|
4c21f7f6f9e3
patch 8.2.1795: Vim9: operators && and || have a confusing result
Bram Moolenaar <Bram@vim.org>
parents:
22441
diff
changeset
|
904 0 && 1 == false |
|
4c21f7f6f9e3
patch 8.2.1795: Vim9: operators && and || have a confusing result
Bram Moolenaar <Bram@vim.org>
parents:
22441
diff
changeset
|
905 8 || 0 Error! |
|
4c21f7f6f9e3
patch 8.2.1795: Vim9: operators && and || have a confusing result
Bram Moolenaar <Bram@vim.org>
parents:
22441
diff
changeset
|
906 'yes' && 0 Error! |
|
4c21f7f6f9e3
patch 8.2.1795: Vim9: operators && and || have a confusing result
Bram Moolenaar <Bram@vim.org>
parents:
22441
diff
changeset
|
907 [] || 99 Error! |
|
19181
94eda51ba9ba
patch 8.2.0149: maintaining a Vim9 branch separately is more work
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
908 |
|
22494
4c21f7f6f9e3
patch 8.2.1795: Vim9: operators && and || have a confusing result
Bram Moolenaar <Bram@vim.org>
parents:
22441
diff
changeset
|
909 When using "!" for inverting, there is no error for using any type and the |
|
22500
ef8a3177edc1
patch 8.2.1798: Vim9: trinary operator condition is too permissive
Bram Moolenaar <Bram@vim.org>
parents:
22494
diff
changeset
|
910 result is a boolean. "!!" can be used to turn any value into boolean: > |
| 23573 | 911 !'yes' == false |
|
22500
ef8a3177edc1
patch 8.2.1798: Vim9: trinary operator condition is too permissive
Bram Moolenaar <Bram@vim.org>
parents:
22494
diff
changeset
|
912 !![] == false |
| 23573 | 913 !![1, 2, 3] == true |
|
22494
4c21f7f6f9e3
patch 8.2.1795: Vim9: operators && and || have a confusing result
Bram Moolenaar <Bram@vim.org>
parents:
22441
diff
changeset
|
914 |
|
4c21f7f6f9e3
patch 8.2.1795: Vim9: operators && and || have a confusing result
Bram Moolenaar <Bram@vim.org>
parents:
22441
diff
changeset
|
915 When using "`.."` for string concatenation arguments of simple types are |
|
22500
ef8a3177edc1
patch 8.2.1798: Vim9: trinary operator condition is too permissive
Bram Moolenaar <Bram@vim.org>
parents:
22494
diff
changeset
|
916 always converted to string: > |
|
19181
94eda51ba9ba
patch 8.2.0149: maintaining a Vim9 branch separately is more work
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
917 'hello ' .. 123 == 'hello 123' |
| 23466 | 918 'hello ' .. v:true == 'hello true' |
|
19181
94eda51ba9ba
patch 8.2.0149: maintaining a Vim9 branch separately is more work
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
919 |
|
26769
30972227ac8d
patch 8.2.3913: help for expressions does not mention Vim9 syntax
Bram Moolenaar <Bram@vim.org>
parents:
26755
diff
changeset
|
920 Simple types are Number, Float, Special and Bool. For other types |string()| |
|
30972227ac8d
patch 8.2.3913: help for expressions does not mention Vim9 syntax
Bram Moolenaar <Bram@vim.org>
parents:
26755
diff
changeset
|
921 should be used. |
|
23497
2247a2ce3630
patch 8.2.2291: Vim9: cannot use "null" for v:null
Bram Moolenaar <Bram@vim.org>
parents:
23466
diff
changeset
|
922 *false* *true* *null* |
|
2247a2ce3630
patch 8.2.2291: Vim9: cannot use "null" for v:null
Bram Moolenaar <Bram@vim.org>
parents:
23466
diff
changeset
|
923 In Vim9 script one can use "true" for v:true, "false" for v:false and "null" |
|
2247a2ce3630
patch 8.2.2291: Vim9: cannot use "null" for v:null
Bram Moolenaar <Bram@vim.org>
parents:
23466
diff
changeset
|
924 for v:null. When converting a boolean to a string "false" and "true" are |
|
2247a2ce3630
patch 8.2.2291: Vim9: cannot use "null" for v:null
Bram Moolenaar <Bram@vim.org>
parents:
23466
diff
changeset
|
925 used, not "v:false" and "v:true" like in legacy script. "v:none" is not |
|
2247a2ce3630
patch 8.2.2291: Vim9: cannot use "null" for v:null
Bram Moolenaar <Bram@vim.org>
parents:
23466
diff
changeset
|
926 changed, it is only used in JSON and has no equivalent in other languages. |
|
19181
94eda51ba9ba
patch 8.2.0149: maintaining a Vim9 branch separately is more work
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
927 |
|
24128
fcbb1d4df15b
patch 8.2.2605: Vim9: string index and slice does not include composing chars
Bram Moolenaar <Bram@vim.org>
parents:
24103
diff
changeset
|
928 Indexing a string with [idx] or taking a slice with [idx : idx] uses character |
|
fcbb1d4df15b
patch 8.2.2605: Vim9: string index and slice does not include composing chars
Bram Moolenaar <Bram@vim.org>
parents:
24103
diff
changeset
|
929 indexes instead of byte indexes. Composing characters are included. |
|
fcbb1d4df15b
patch 8.2.2605: Vim9: string index and slice does not include composing chars
Bram Moolenaar <Bram@vim.org>
parents:
24103
diff
changeset
|
930 Example: > |
| 21825 | 931 echo 'bár'[1] |
| 932 In legacy script this results in the character 0xc3 (an illegal byte), in Vim9 | |
| 933 script this results in the string 'á'. | |
| 23573 | 934 A negative index is counting from the end, "[-1]" is the last character. |
| 23666 | 935 To exclude the last character use |slice()|. |
|
24272
cabed216cc2f
patch 8.2.2677: Vim9: cannot use only some of the default arguments
Bram Moolenaar <Bram@vim.org>
parents:
24150
diff
changeset
|
936 To count composing characters separately use |strcharpart()|. |
| 23573 | 937 If the index is out of range then an empty string results. |
| 938 | |
| 939 In legacy script "++var" and "--var" would be silently accepted and have no | |
| 940 effect. This is an error in Vim9 script. | |
| 941 | |
| 942 Numbers starting with zero are not considered to be octal, only numbers | |
| 943 starting with "0o" are octal: "0o744". |scriptversion-4| | |
| 21825 | 944 |
|
19181
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patch 8.2.0149: maintaining a Vim9 branch separately is more work
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
945 |
| 21093 | 946 What to watch out for ~ |
| 947 *vim9-gotchas* | |
| 948 Vim9 was designed to be closer to often used programming languages, but at the | |
| 949 same time tries to support the legacy Vim commands. Some compromises had to | |
| 950 be made. Here is a summary of what might be unexpected. | |
| 951 | |
| 952 Ex command ranges need to be prefixed with a colon. > | |
| 23666 | 953 -> legacy Vim: shifts the previous line to the right |
| 954 ->func() Vim9: method call in a continuation line | |
| 955 :-> Vim9: shifts the previous line to the right | |
| 21093 | 956 |
| 23666 | 957 %s/a/b legacy Vim: substitute on all lines |
| 21093 | 958 x = alongname |
| 23666 | 959 % another Vim9: modulo operator in a continuation line |
| 960 :%s/a/b Vim9: substitute on all lines | |
| 961 't legacy Vim: jump to mark t | |
| 962 'text'->func() Vim9: method call | |
| 963 :'t Vim9: jump to mark t | |
| 21093 | 964 |
| 21676 | 965 Some Ex commands can be confused with assignments in Vim9 script: > |
| 23666 | 966 g:name = value # assignment |
|
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967 :g:pattern:cmd # :global command |
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968 |
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969 To avoid confusion between a `:global` or `:substitute` command and an |
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970 expression or assignment, a few separators cannot be used when these commands |
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971 are abbreviated to a single character: ':', '-' and '.'. > |
| 23666 | 972 g:pattern:cmd # invalid command - ERROR |
|
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973 s:pattern:repl # invalid command - ERROR |
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974 g-pattern-cmd # invalid command - ERROR |
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975 s-pattern-repl # invalid command - ERROR |
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976 g.pattern.cmd # invalid command - ERROR |
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977 s.pattern.repl # invalid command - ERROR |
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978 |
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979 Also, there cannot be a space between the command and the separator: > |
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980 g /pattern/cmd # invalid command - ERROR |
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981 s /pattern/repl # invalid command - ERROR |
| 21676 | 982 |
| 21093 | 983 Functions defined with `:def` compile the whole function. Legacy functions |
| 984 can bail out, and the following lines are not parsed: > | |
| 985 func Maybe() | |
| 986 if !has('feature') | |
| 987 return | |
| 988 endif | |
| 989 use-feature | |
| 990 endfunc | |
| 991 Vim9 functions are compiled as a whole: > | |
| 992 def Maybe() | |
| 993 if !has('feature') | |
| 994 return | |
| 995 endif | |
| 23573 | 996 use-feature # May give a compilation error |
| 21093 | 997 enddef |
| 998 For a workaround, split it in two functions: > | |
| 999 func Maybe() | |
| 1000 if has('feature') | |
| 23666 | 1001 call MaybeInner() |
| 21093 | 1002 endif |
| 1003 endfunc | |
| 1004 if has('feature') | |
| 1005 def MaybeInner() | |
| 1006 use-feature | |
| 1007 enddef | |
| 1008 endif | |
| 22171 | 1009 Or put the unsupported code inside an `if` with a constant expression that |
| 21991 | 1010 evaluates to false: > |
| 1011 def Maybe() | |
| 1012 if has('feature') | |
| 1013 use-feature | |
| 1014 endif | |
| 1015 enddef | |
| 25619 | 1016 The `exists_compiled()` function can also be used for this. |
| 1017 *vim9-user-command* | |
| 23666 | 1018 Another side effect of compiling a function is that the presence of a user |
| 23573 | 1019 command is checked at compile time. If the user command is defined later an |
| 1020 error will result. This works: > | |
| 1021 command -nargs=1 MyCommand echom <q-args> | |
| 1022 def Works() | |
| 1023 MyCommand 123 | |
| 1024 enddef | |
| 1025 This will give an error for "MyCommand" not being defined: > | |
| 1026 def Works() | |
| 1027 command -nargs=1 MyCommand echom <q-args> | |
| 1028 MyCommand 123 | |
| 1029 enddef | |
| 1030 A workaround is to invoke the command indirectly with `:execute`: > | |
| 1031 def Works() | |
| 1032 command -nargs=1 MyCommand echom <q-args> | |
| 1033 execute 'MyCommand 123' | |
| 1034 enddef | |
| 1035 | |
| 21991 | 1036 Note that for unrecognized commands there is no check for "|" and a following |
| 1037 command. This will give an error for missing `endif`: > | |
| 1038 def Maybe() | |
| 1039 if has('feature') | use-feature | endif | |
| 1040 enddef | |
| 21093 | 1041 |
| 23305 | 1042 Other differences ~ |
| 1043 | |
| 1044 Patterns are used like 'magic' is set, unless explicitly overruled. | |
| 1045 The 'edcompatible' option value is not used. | |
| 1046 The 'gdefault' option value is not used. | |
| 1047 | |
| 24387 | 1048 You may also find this wiki useful. It was written by an early adopter of |
| 24103 | 1049 Vim9 script: https://github.com/lacygoill/wiki/blob/master/vim/vim9.md |
| 23305 | 1050 |
| 25056 | 1051 *:++* *:--* |
| 1052 The ++ and -- commands have been added. They are very similar to adding or | |
| 1053 subtracting one: > | |
| 1054 ++var | |
| 1055 var += 1 | |
| 1056 --var | |
| 1057 var -= 1 | |
| 1058 | |
| 1059 Using ++var or --var in an expression is not supported yet. | |
| 1060 | |
|
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1061 ============================================================================== |
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1062 |
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1063 3. New style functions *fast-functions* |
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1064 |
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1065 *:def* |
| 21825 | 1066 :def[!] {name}([arguments])[: {return-type}] |
|
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1067 Define a new function by the name {name}. The body of |
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1068 the function follows in the next lines, until the |
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1069 matching `:enddef`. |
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1070 |
|
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1071 When {return-type} is omitted or is "void" the |
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1072 function is not expected to return anything. |
|
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1073 |
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1074 {arguments} is a sequence of zero or more argument |
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1075 declarations. There are three forms: |
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1076 {name}: {type} |
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1077 {name} = {value} |
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1078 {name}: {type} = {value} |
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1079 The first form is a mandatory argument, the caller |
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1080 must always provide them. |
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1081 The second and third form are optional arguments. |
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1082 When the caller omits an argument the {value} is used. |
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1083 |
| 20856 | 1084 The function will be compiled into instructions when |
| 21499 | 1085 called, or when `:disassemble` or `:defcompile` is |
| 1086 used. Syntax and type errors will be produced at that | |
| 1087 time. | |
| 20856 | 1088 |
| 21499 | 1089 It is possible to nest `:def` inside another `:def` or |
| 1090 `:function` up to about 50 levels deep. | |
| 19303 | 1091 |
|
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1092 [!] is used as with `:function`. Note that |
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1093 script-local functions cannot be deleted or redefined |
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1094 later in Vim9 script. They can only be removed by |
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1095 reloading the same script. |
|
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1096 |
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1097 *:enddef* |
| 21499 | 1098 :enddef End of a function defined with `:def`. It should be on |
| 1099 a line by its own. | |
|
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1100 |
| 24387 | 1101 You may also find this wiki useful. It was written by an early adopter of |
|
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1102 Vim9 script: https://github.com/lacygoill/wiki/blob/master/vim/vim9.md |
|
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1103 |
|
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1104 If the script the function is defined in is Vim9 script, then script-local |
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1105 variables can be accessed without the "s:" prefix. They must be defined |
| 20856 | 1106 before the function is compiled. If the script the function is defined in is |
| 1107 legacy script, then script-local variables must be accessed with the "s:" | |
| 24387 | 1108 prefix if they do not exist at the time of compiling. |
|
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1109 |
| 20552 | 1110 *:defc* *:defcompile* |
| 1111 :defc[ompile] Compile functions defined in the current script that | |
| 1112 were not compiled yet. | |
| 1113 This will report errors found during the compilation. | |
|
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1114 |
| 19404 | 1115 *:disa* *:disassemble* |
| 1116 :disa[ssemble] {func} Show the instructions generated for {func}. | |
| 1117 This is for debugging and testing. | |
|
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1118 Note that for command line completion of {func} you |
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1119 can prepend "s:" to find script-local functions. |
| 19404 | 1120 |
| 24911 | 1121 :disa[ssemble] profile {func} |
| 1122 Like `:disassemble` but with the instructions used for | |
| 23737 | 1123 profiling. |
| 1124 | |
| 24911 | 1125 :disa[ssemble] debug {func} |
| 1126 Like `:disassemble` but with the instructions used for | |
| 1127 debugging. | |
| 1128 | |
| 21250 | 1129 Limitations ~ |
| 1130 | |
| 1131 Local variables will not be visible to string evaluation. For example: > | |
|
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1132 def MapList(): list<string> |
|
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1133 var list = ['aa', 'bb', 'cc', 'dd'] |
| 21250 | 1134 return range(1, 2)->map('list[v:val]') |
| 1135 enddef | |
| 1136 | |
| 1137 The map argument is a string expression, which is evaluated without the | |
| 1138 function scope. Instead, use a lambda: > | |
|
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1139 def MapList(): list<string> |
|
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1140 var list = ['aa', 'bb', 'cc', 'dd'] |
| 25973 | 1141 return range(1, 2)->map((_, v) => list[v]) |
| 21250 | 1142 enddef |
| 1143 | |
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1144 For commands that are not compiled, such as `:edit`, backtick expansion can be |
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1145 used and it can use the local scope. Example: > |
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1146 def Replace() |
|
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1147 var fname = 'blah.txt' |
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1148 edit `=fname` |
| 25402 | 1149 enddef |
| 1150 | |
| 24278 | 1151 Closures defined in a loop will share the same context. For example: > |
| 1152 var flist: list<func> | |
| 25402 | 1153 for i in range(5) |
| 24278 | 1154 var inloop = i |
| 1155 flist[i] = () => inloop | |
| 1156 endfor | |
| 25402 | 1157 echo range(5)->map((i, _) => flist[i]()) |
| 1158 # Result: [4, 4, 4, 4, 4] | |
| 24278 | 1159 |
| 1160 The "inloop" variable will exist only once, all closures put in the list refer | |
| 25402 | 1161 to the same instance, which in the end will have the value 4. This is |
| 1162 efficient, also when looping many times. If you do want a separate context | |
| 1163 for each closure call a function to define it: > | |
| 1164 def GetClosure(i: number): func | |
| 1165 var infunc = i | |
| 1166 return () => infunc | |
| 24278 | 1167 enddef |
| 1168 | |
| 1169 var flist: list<func> | |
| 25402 | 1170 for i in range(5) |
| 1171 flist[i] = GetClosure(i) | |
| 24278 | 1172 endfor |
| 25402 | 1173 echo range(5)->map((i, _) => flist[i]()) |
| 1174 # Result: [0, 1, 2, 3, 4] | |
| 24278 | 1175 |
|
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1176 ============================================================================== |
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1177 |
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1178 4. Types *vim9-types* |
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1179 |
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1180 The following builtin types are supported: |
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1181 bool |
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1182 number |
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1183 float |
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1184 string |
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1185 blob |
|
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1186 list<{type}> |
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1187 dict<{type}> |
|
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1188 job |
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1189 channel |
| 19646 | 1190 func |
| 19968 | 1191 func: {type} |
|
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1192 func({type}, ...) |
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1193 func({type}, ...): {type} |
|
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1194 |
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1195 Not supported yet: |
|
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1196 tuple<a: {type}, b: {type}, ...> |
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1197 |
| 25161 | 1198 These types can be used in declarations, but no simple value will actually |
| 1199 have the "void" type. | |
|
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1200 |
|
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1201 There is no array type, use list<{type}> instead. For a list constant an |
|
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1202 efficient implementation is used that avoids allocating lot of small pieces of |
|
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1203 memory. |
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1204 |
|
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1205 A partial and function can be declared in more or less specific ways: |
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1206 func any kind of function reference, no type |
| 19968 | 1207 checking for arguments or return value |
| 25161 | 1208 func: void any number and type of arguments, no return |
| 1209 value | |
|
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1210 func: {type} any number and type of arguments with specific |
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1211 return type |
| 25161 | 1212 |
| 1213 func() function with no argument, does not return a | |
| 1214 value | |
| 1215 func(): void same | |
| 1216 func(): {type} function with no argument and return type | |
| 1217 | |
| 19968 | 1218 func({type}) function with argument type, does not return |
|
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1219 a value |
| 19968 | 1220 func({type}): {type} function with argument type and return type |
| 1221 func(?{type}) function with type of optional argument, does | |
| 1222 not return a value | |
| 1223 func(...{type}) function with type of variable number of | |
| 1224 arguments, does not return a value | |
| 1225 func({type}, ?{type}, ...{type}): {type} | |
| 1226 function with: | |
| 1227 - type of mandatory argument | |
| 1228 - type of optional argument | |
| 1229 - type of variable number of arguments | |
| 1230 - return type | |
|
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1231 |
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1232 If the return type is "void" the function does not return a value. |
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1233 |
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1234 The reference can also be a |Partial|, in which case it stores extra arguments |
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1235 and/or a dictionary, which are not visible to the caller. Since they are |
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1236 called in the same way the declaration is the same. |
|
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1237 |
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1238 Custom types can be defined with `:type`: > |
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1239 :type MyList list<string> |
|
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1240 Custom types must start with a capital letter, to avoid name clashes with |
|
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1241 builtin types added later, similarly to user functions. |
|
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1242 {not implemented yet} |
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1243 |
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1244 And classes and interfaces can be used as types: > |
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1245 :class MyClass |
|
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1246 :var mine: MyClass |
|
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1247 |
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1248 :interface MyInterface |
|
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1249 :var mine: MyInterface |
|
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1250 |
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1251 :class MyTemplate<Targ> |
|
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1252 :var mine: MyTemplate<number> |
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1253 :var mine: MyTemplate<string> |
|
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1254 |
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1255 :class MyInterface<Targ> |
|
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1256 :var mine: MyInterface<number> |
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1257 :var mine: MyInterface<string> |
|
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1258 {not implemented yet} |
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1259 |
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1260 |
|
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|
1261 Variable types and type casting ~ |
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1262 *variable-types* |
|
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1263 Variables declared in Vim9 script or in a `:def` function have a type, either |
|
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|
1264 specified explicitly or inferred from the initialization. |
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1265 |
|
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|
1266 Global, buffer, window and tab page variables do not have a specific type, the |
|
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1267 value can be changed at any time, possibly changing the type. Therefore, in |
|
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1268 compiled code the "any" type is assumed. |
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1269 |
|
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|
1270 This can be a problem when the "any" type is undesired and the actual type is |
|
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1271 expected to always be the same. For example, when declaring a list: > |
|
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1272 var l: list<number> = [1, g:two] |
| 23305 | 1273 At compile time Vim doesn't know the type of "g:two" and the expression type |
| 1274 becomes list<any>. An instruction is generated to check the list type before | |
| 1275 doing the assignment, which is a bit inefficient. | |
| 1276 *type-casting* | |
| 1277 To avoid this, use a type cast: > | |
|
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1278 var l: list<number> = [1, <number>g:two] |
| 23305 | 1279 The compiled code will then only check that "g:two" is a number and give an |
| 1280 error if it isn't. This is called type casting. | |
|
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1281 |
|
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1282 The syntax of a type cast is: "<" {type} ">". There cannot be white space |
|
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1283 after the "<" or before the ">" (to avoid them being confused with |
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1284 smaller-than and bigger-than operators). |
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1285 |
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1286 The semantics is that, if needed, a runtime type check is performed. The |
|
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1287 value is not actually changed. If you need to change the type, e.g. to change |
|
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1288 it to a string, use the |string()| function. Or use |str2nr()| to convert a |
|
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1289 string to a number. |
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1290 |
|
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1291 |
|
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1292 Type inference ~ |
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1293 *type-inference* |
|
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1294 In general: Whenever the type is clear it can be omitted. For example, when |
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1295 declaring a variable and giving it a value: > |
|
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1296 var name = 0 # infers number type |
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1297 var name = 'hello' # infers string type |
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1298 |
|
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1299 The type of a list and dictionary comes from the common type of the values. |
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1300 If the values all have the same type, that type is used for the list or |
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1301 dictionary. If there is a mix of types, the "any" type is used. > |
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1302 [1, 2, 3] list<number> |
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1303 ['a', 'b', 'c'] list<string> |
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1304 [1, 'x', 3] list<any> |
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1305 |
| 25161 | 1306 The common type of function references, if they do not all have the same |
| 1307 number of arguments, uses "(...)" to indicate the number of arguments is not | |
| 1308 specified. For example: > | |
| 1309 def Foo(x: bool) | |
| 1310 enddef | |
| 1311 def Bar(x: bool, y: bool) | |
| 1312 enddef | |
| 1313 var funclist = [Foo, Bar] | |
| 1314 echo funclist->typename() | |
| 1315 Results in: | |
| 1316 list<func(...)> | |
| 1317 | |
| 24387 | 1318 For script-local variables in Vim9 script the type is checked, also when the |
| 1319 variable was declared in a legacy function. | |
| 1320 | |
| 21991 | 1321 |
|
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1322 Stricter type checking ~ |
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1323 *type-checking* |
| 21991 | 1324 In legacy Vim script, where a number was expected, a string would be |
| 1325 automatically converted to a number. This was convenient for an actual number | |
| 24387 | 1326 such as "123", but leads to unexpected problems (and no error message) if the |
| 21991 | 1327 string doesn't start with a number. Quite often this leads to hard-to-find |
| 1328 bugs. | |
| 1329 | |
| 1330 In Vim9 script this has been made stricter. In most places it works just as | |
| 22171 | 1331 before, if the value used matches the expected type. There will sometimes be |
| 1332 an error, thus breaking backwards compatibility. For example: | |
| 21991 | 1333 - Using a number other than 0 or 1 where a boolean is expected. *E1023* |
| 25161 | 1334 - Using a string value when setting a number option. |
| 21991 | 1335 - Using a number where a string is expected. *E1024* |
| 1336 | |
| 25973 | 1337 One consequence is that the item type of a list or dict given to |map()| must |
| 24024 | 1338 not change. This will give an error in Vim9 script: > |
| 25973 | 1339 echo map([1, 2, 3], (i, v) => 'item ' .. i) |
| 24024 | 1340 E1012: Type mismatch; expected number but got string |
| 25973 | 1341 Instead use |mapnew()|: > |
| 1342 echo mapnew([1, 2, 3], (i, v) => 'item ' .. i) | |
| 25161 | 1343 ['item 0', 'item 1', 'item 2'] |
| 1344 | |
| 1345 If the item type was determined to be "any" it can change to a more specific | |
| 25973 | 1346 type. E.g. when a list of mixed types gets changed to a list of strings: > |
| 25161 | 1347 var mylist = [1, 2.0, '3'] |
| 1348 # typename(mylist) == "list<any>" | |
| 1349 map(mylist, (i, v) => 'item ' .. i) | |
| 1350 # typename(mylist) == "list<string>", no error | |
| 1351 | |
| 24024 | 1352 Same for |extend()|, use |extendnew()| instead, and for |flatten()|, use |
| 1353 |flattennew()| instead. | |
| 23573 | 1354 |
|
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1355 ============================================================================== |
|
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1356 |
|
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|
1357 5. Namespace, Import and Export |
|
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1358 *vim9script* *vim9-export* *vim9-import* |
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1359 |
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1360 A Vim9 script can be written to be imported. This means that everything in |
|
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1361 the script is local, unless exported. Those exported items, and only those |
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1362 items, can then be imported in another script. |
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1363 |
| 21991 | 1364 You can cheat by using the global namespace explicitly. We will assume here |
| 1365 that you don't do that. | |
| 1366 | |
|
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1367 |
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1368 Namespace ~ |
|
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1369 *vim9-namespace* |
| 19303 | 1370 To recognize a file that can be imported the `vim9script` statement must |
|
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1371 appear as the first statement in the file (see |vim9-mix| for an exception). |
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|
1372 It tells Vim to interpret the script in its own namespace, instead of the |
|
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1373 global namespace. If a file starts with: > |
|
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1374 vim9script |
|
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1375 var myvar = 'yes' |
|
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1376 Then "myvar" will only exist in this file. While without `vim9script` it would |
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1377 be available as `g:myvar` from any other script and function. |
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1378 |
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1379 The variables at the file level are very much like the script-local "s:" |
| 20115 | 1380 variables in legacy Vim script, but the "s:" is omitted. And they cannot be |
| 1381 deleted. | |
|
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1382 |
| 20115 | 1383 In Vim9 script the global "g:" namespace can still be used as before. And the |
| 1384 "w:", "b:" and "t:" namespaces. These have in common that variables are not | |
| 1385 declared and they can be deleted. | |
|
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1386 |
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1387 A side effect of `:vim9script` is that the 'cpoptions' option is set to the |
|
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1388 Vim default value, like with: > |
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1389 :set cpo&vim |
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1390 One of the effects is that |line-continuation| is always enabled. |
|
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|
1391 The original value of 'cpoptions' is restored at the end of the script, while |
|
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|
1392 flags added or removed in the script are also added to or removed from the |
|
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|
1393 original value to get the same effect. The order of flags may change. |
|
26745
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|
1394 In the |vimrc| file sourced on startup this does not happen. |
|
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1395 |
|
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1396 *vim9-mix* |
|
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1397 There is one way to use both legacy and Vim9 syntax in one script file: > |
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1398 " comments may go here |
|
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1399 if !has('vim9script') |
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1400 " legacy script commands go here |
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1401 finish |
|
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1402 endif |
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1403 vim9script |
|
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|
1404 # Vim9 script commands go here |
|
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|
1405 This allows for writing a script that takes advantage of the Vim9 script |
| 24024 | 1406 syntax if possible, but will also work on a Vim version without it. |
|
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|
1407 |
|
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|
1408 This can only work in two ways: |
|
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|
1409 1. The "if" statement evaluates to false, the commands up to `endif` are |
|
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|
1410 skipped and `vim9script` is then the first command actually executed. |
|
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|
1411 2. The "if" statement evaluates to true, the commands up to `endif` are |
|
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|
1412 executed and `finish` bails out before reaching `vim9script`. |
|
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|
1413 |
|
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|
1414 |
|
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|
1415 Export ~ |
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1416 *:export* *:exp* |
| 21499 | 1417 Exporting an item can be written as: > |
|
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|
1418 export const EXPORTED_CONST = 1234 |
|
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1419 export var someValue = ... |
|
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|
1420 export final someValue = ... |
|
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|
1421 export const someValue = ... |
|
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|
1422 export def MyFunc() ... |
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1423 export class MyClass ... |
|
24888
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|
1424 export interface MyClass ... |
|
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|
1425 |
|
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|
1426 As this suggests, only constants, variables, `:def` functions and classes can |
|
24888
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|
1427 be exported. {not implemented yet: class, interface} |
|
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|
1428 |
| 20856 | 1429 *E1042* |
| 1430 `:export` can only be used in Vim9 script, at the script level. | |
|
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|
1431 |
|
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|
1432 |
|
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|
1433 Import ~ |
| 20965 | 1434 *:import* *:imp* *E1094* |
|
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|
1435 The exported items can be imported in another Vim9 script: > |
|
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|
1436 import "myscript.vim" |
|
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1437 |
|
26980
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|
1438 This makes each item available as "myscript.item". |
|
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1439 |
|
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|
1440 In case the name is long or ambiguous, another name can be specified: > |
|
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|
1441 import "thatscript.vim" as That |
|
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1442 |
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|
1443 Then you can use "That.EXPORTED_CONST", "That.someValue", etc. You are free |
|
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|
1444 to choose the name "That". Use something that will be recognized as referring |
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|
1445 to the imported script. Avoid command names, because the name will shadow |
|
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|
1446 them. |
|
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1447 |
|
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|
1448 In case the dot in the name is unwanted, a local reference can be made: > |
|
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|
1449 var ThatFunc = That.LongFuncName |
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1450 |
|
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|
1451 This also works for constants: > |
|
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|
1452 cost MAXLEN = That.MAX_LEN_OF_NAME |
|
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|
1453 |
|
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|
1454 This does not work for variables, you could use a setter function and make a |
|
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|
1455 local reference for it. |
|
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1456 |
| 22171 | 1457 `:import` can also be used in legacy Vim script. The imported items still |
| 1458 become script-local, even when the "s:" prefix is not given. | |
| 1459 | |
|
25282
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|
1460 `:import` can not be used in a function. Imported items are intended to exist |
|
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|
1461 at the script level and only imported once. |
|
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|
1462 |
|
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1463 The script name after `import` can be: |
|
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1464 - A relative path, starting "." or "..". This finds a file relative to the |
|
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|
1465 location of the script file itself. This is useful to split up a large |
|
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1466 plugin into several files. |
|
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1467 - An absolute path, starting with "/" on Unix or "D:/" on MS-Windows. This |
| 22723 | 1468 will rarely be used. |
|
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1469 - A path not being relative or absolute. This will be found in the |
|
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|
1470 "import" subdirectories of 'runtimepath' entries. The name will usually be |
|
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1471 longer and unique, to avoid loading the wrong file. |
| 25619 | 1472 Note that "after/import" is not used. |
|
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1473 |
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1474 Once a vim9 script file has been imported, the result is cached and used the |
|
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1475 next time the same script is imported. It will not be read again. |
|
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1476 |
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|
1477 It is not allowed to import the same script twice, also when using two |
|
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1478 different "as" names. |
|
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1479 *:import-cycle* |
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1480 The `import` commands are executed when encountered. If that script (directly |
|
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1481 or indirectly) imports the current script, then items defined after the |
|
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1482 `import` won't be processed yet. Therefore cyclic imports can exist, but may |
|
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1483 result in undefined items. |
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1484 |
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1485 |
|
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|
1486 Import in an autoload script ~ |
|
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1487 |
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1488 For optimal startup speed, loading scripts should be postponed until they are |
| 19303 | 1489 actually needed. A recommended mechanism: |
|
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1490 |
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1491 1. In the plugin define user commands, functions and/or mappings that refer to |
|
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1492 an autoload script. > |
| 23666 | 1493 command -nargs=1 SearchForStuff searchfor#Stuff(<f-args>) |
|
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1494 |
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|
1495 < This goes in .../plugin/anyname.vim. "anyname.vim" can be freely chosen. |
|
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1496 |
| 21825 | 1497 2. In the autoload script do the actual work. You can import items from |
|
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1498 other files to split up functionality in appropriate pieces. > |
|
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1499 vim9script |
|
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|
1500 import "../import/someother.vim" as other |
|
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1501 def searchfor#Stuff(arg: string) |
|
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|
1502 var filtered = other.FilterFunc(arg) |
|
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1503 ... |
|
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1504 < This goes in .../autoload/searchfor.vim. "searchfor" in the file name |
|
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1505 must be exactly the same as the prefix for the function name, that is how |
|
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1506 Vim finds the file. |
|
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1507 |
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1508 3. Other functionality, possibly shared between plugins, contains the exported |
|
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1509 items and any private items. > |
|
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1510 vim9script |
|
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|
1511 var localVar = 'local' |
| 22171 | 1512 export def FilterFunc(arg: string): string |
|
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1513 ... |
|
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1514 < This goes in .../import/someother.vim. |
|
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1515 |
|
21771
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|
1516 When compiling a `:def` function and a function in an autoload script is |
|
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|
1517 encountered, the script is not loaded until the `:def` function is called. |
|
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|
1518 |
|
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1519 |
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|
1520 Import in legacy Vim script ~ |
|
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1521 |
| 20856 | 1522 If an `import` statement is used in legacy Vim script, the script-local "s:" |
| 1523 namespace will be used for the imported item, even when "s:" is not specified. | |
|
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1524 |
|
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|
1525 |
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|
1526 ============================================================================== |
|
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1527 |
| 22328 | 1528 6. Future work: classes *vim9-classes* |
| 1529 | |
| 1530 Above "class" was mentioned a few times, but it has not been implemented yet. | |
|
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|
1531 Most of Vim9 script can be created without this functionality, and since |
| 22328 | 1532 implementing classes is going to be a lot of work, it is left for the future. |
| 1533 For now we'll just make sure classes can be added later. | |
| 1534 | |
| 1535 Thoughts: | |
|
24888
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|
1536 - `class` / `endclass`, the whole class must be in one file |
|
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|
1537 - Class names are always CamelCase (to avoid a name clash with builtin types) |
|
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|
1538 - A single constructor called "constructor" |
| 22328 | 1539 - Single inheritance with `class ThisClass extends BaseClass` |
|
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1540 - `abstract class` (class with incomplete implementation) |
|
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|
1541 - `interface` / `endinterface` (abstract class without any implementation) |
| 22328 | 1542 - `class SomeClass implements SomeInterface` |
| 1543 - Generics for class: `class <Tkey, Tentry>` | |
| 1544 - Generics for function: `def <Tkey> GetLast(key: Tkey)` | |
| 1545 | |
|
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|
1546 Again, much of this is from TypeScript with a slightly different syntax. |
| 22328 | 1547 |
| 1548 Some things that look like good additions: | |
| 1549 - Use a class as an interface (like Dart) | |
| 1550 - Extend a class with methods, using an import (like Dart) | |
|
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|
1551 - Mixins |
|
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|
1552 - For testing: Mock mechanism |
| 22328 | 1553 |
| 1554 An important class that will be provided is "Promise". Since Vim is single | |
| 1555 threaded, connecting asynchronous operations is a natural way of allowing | |
| 1556 plugins to do their work without blocking the user. It's a uniform way to | |
| 1557 invoke callbacks and handle timeouts and errors. | |
| 1558 | |
|
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|
1559 Some examples: > |
|
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|
1560 |
|
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|
1561 abstract class Person |
|
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|
1562 static const prefix = 'xxx' |
|
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|
1563 var name: string |
|
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|
1564 |
|
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|
1565 def constructor(name: string) |
| 25402 | 1566 this.name = name |
|
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|
1567 enddef |
|
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1568 |
|
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|
1569 def display(): void |
|
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|
1570 echo name |
|
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|
1571 enddef |
|
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1572 |
|
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|
1573 abstract def find(string): Person |
|
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|
1574 endclass |
|
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1575 |
| 22328 | 1576 ============================================================================== |
| 1577 | |
|
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1578 9. Rationale *vim9-rationale* |
|
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1579 |
|
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|
1580 The :def command ~ |
|
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1581 |
|
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|
1582 Plugin writers have asked for much faster Vim script. Investigations have |
| 19303 | 1583 shown that keeping the existing semantics of function calls make this close to |
|
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|
1584 impossible, because of the overhead involved with calling a function, setting |
|
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|
1585 up the local function scope and executing lines. There are many details that |
|
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1586 need to be handled, such as error messages and exceptions. The need to create |
|
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|
1587 a dictionary for a: and l: scopes, the a:000 list and several others add too |
|
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|
1588 much overhead that cannot be avoided. |
|
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|
1589 |
|
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|
1590 Therefore the `:def` method to define a new-style function had to be added, |
|
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|
1591 which allows for a function with different semantics. Most things still work |
|
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|
1592 as before, but some parts do not. A new way to define a function was |
|
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|
1593 considered the best way to separate the legacy style code from Vim9 style code. |
|
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1594 |
|
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|
1595 Using "def" to define a function comes from Python. Other languages use |
|
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|
1596 "function" which clashes with legacy Vim script. |
|
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1597 |
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1598 |
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1599 Type checking ~ |
|
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|
1600 |
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|
1601 When compiling lines of Vim commands into instructions as much as possible |
|
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1602 should be done at compile time. Postponing it to runtime makes the execution |
|
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1603 slower and means mistakes are found only later. For example, when |
|
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|
1604 encountering the "+" character and compiling this into a generic add |
| 23666 | 1605 instruction, at runtime the instruction would have to inspect the type of the |
| 1606 arguments and decide what kind of addition to do. And when the type is | |
| 1607 dictionary throw an error. If the types are known to be numbers then an "add | |
| 1608 number" instruction can be used, which is faster. The error can be given at | |
| 1609 compile time, no error handling is needed at runtime, since adding two numbers | |
| 1610 cannot fail. | |
|
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1611 |
|
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1612 The syntax for types, using <type> for compound types, is similar to Java. It |
|
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|
1613 is easy to understand and widely used. The type names are what were used in |
|
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|
1614 Vim before, with some additions such as "void" and "bool". |
|
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1615 |
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1616 |
| 22328 | 1617 Removing clutter and weirdness ~ |
| 20856 | 1618 |
| 22328 | 1619 Once decided that `:def` functions have different syntax than legacy functions, |
| 1620 we are free to add improvements to make the code more familiar for users who | |
| 1621 know popular programming languages. In other words: remove weird things that | |
|
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1622 only Vim does. |
| 22328 | 1623 |
| 1624 We can also remove clutter, mainly things that were done to make Vim script | |
|
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|
1625 backwards compatible with the good old Vi commands. |
| 20856 | 1626 |
| 22328 | 1627 Examples: |
| 1628 - Drop `:call` for calling a function and `:eval` for manipulating data. | |
| 1629 - Drop using a leading backslash for line continuation, automatically figure | |
| 1630 out where an expression ends. | |
| 20856 | 1631 |
| 22328 | 1632 However, this does require that some things need to change: |
| 1633 - Comments start with # instead of ", to avoid confusing them with strings. | |
|
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1634 This is good anyway, it is known from several popular languages. |
| 22328 | 1635 - Ex command ranges need to be prefixed with a colon, to avoid confusion with |
| 1636 expressions (single quote can be a string or a mark, "/" can be divide or a | |
| 1637 search command, etc.). | |
| 1638 | |
| 1639 Goal is to limit the differences. A good criteria is that when the old syntax | |
|
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|
1640 is accidentally used you are very likely to get an error message. |
| 20856 | 1641 |
| 1642 | |
|
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|
1643 Syntax and semantics from popular languages ~ |
|
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1644 |
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1645 Script writers have complained that the Vim script syntax is unexpectedly |
|
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1646 different from what they are used to. To reduce this complaint popular |
| 20856 | 1647 languages are used as an example. At the same time, we do not want to abandon |
| 1648 the well-known parts of legacy Vim script. | |
|
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1649 |
|
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|
1650 For many things TypeScript is followed. It's a recent language that is |
|
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|
1651 gaining popularity and has similarities with Vim script. It also has a |
| 22328 | 1652 mix of static typing (a variable always has a known value type) and dynamic |
|
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1653 typing (a variable can have different types, this changes at runtime). Since |
| 22328 | 1654 legacy Vim script is dynamically typed and a lot of existing functionality |
| 1655 (esp. builtin functions) depends on that, while static typing allows for much | |
| 1656 faster execution, we need to have this mix in Vim9 script. | |
| 1657 | |
| 22171 | 1658 There is no intention to completely match TypeScript syntax and semantics. We |
| 1659 just want to take those parts that we can use for Vim and we expect Vim users | |
| 22328 | 1660 will be happy with. TypeScript is a complex language with its own history, |
| 1661 advantages and disadvantages. To get an idea of the disadvantages read the | |
| 1662 book: "JavaScript: The Good Parts". Or find the article "TypeScript: the good | |
|
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1663 parts" and read the "Things to avoid" section. |
|
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1664 |
| 22328 | 1665 People familiar with other languages (Java, Python, etc.) will also find |
| 1666 things in TypeScript that they do not like or do not understand. We'll try to | |
| 1667 avoid those things. | |
|
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1668 |
|
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|
1669 Specific items from TypeScript we avoid: |
|
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1670 - Overloading "+", using it both for addition and string concatenation. This |
|
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|
1671 goes against legacy Vim script and often leads to mistakes. For that reason |
|
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|
1672 we will keep using ".." for string concatenation. Lua also uses ".." this |
|
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|
1673 way. And it allows for conversion to string for more values. |
|
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1674 - TypeScript can use an expression like "99 || 'yes'" in a condition, but |
|
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|
1675 cannot assign the value to a boolean. That is inconsistent and can be |
|
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|
1676 annoying. Vim recognizes an expression with && or || and allows using the |
|
26755
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|
1677 result as a bool. The |falsy-operator| was added for the mechanism to use a |
|
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|
1678 default value. |
|
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1679 - TypeScript considers an empty string as Falsy, but an empty list or dict as |
|
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|
1680 Truthy. That is inconsistent. In Vim an empty list and dict are also |
|
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|
1681 Falsy. |
|
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|
1682 - TypeScript has various "Readonly" types, which have limited usefulness, |
|
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|
1683 since a type cast can remove the immutable nature. Vim locks the value, |
|
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|
1684 which is more flexible, but is only checked at runtime. |
| 22171 | 1685 |
|
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1686 |
|
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|
1687 Declarations ~ |
|
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1688 |
|
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|
1689 Legacy Vim script uses `:let` for every assignment, while in Vim9 declarations |
|
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|
1690 are used. That is different, thus it's good to use a different command: |
|
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|
1691 `:var`. This is used in many languages. The semantics might be slightly |
|
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|
1692 different, but it's easily recognized as a declaration. |
|
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1693 |
| 23047 | 1694 Using `:const` for constants is common, but the semantics varies. Some |
|
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|
1695 languages only make the variable immutable, others also make the value |
|
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|
1696 immutable. Since "final" is well known from Java for only making the variable |
|
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|
1697 immutable we decided to use that. And then `:const` can be used for making |
|
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|
1698 both immutable. This was also used in legacy Vim script and the meaning is |
|
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|
1699 almost the same. |
|
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|
1700 |
|
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|
1701 What we end up with is very similar to Dart: > |
|
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|
1702 :var name # mutable variable and value |
|
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1703 :final name # immutable variable, mutable value |
|
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1704 :const name # immutable variable and value |
|
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1705 |
|
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|
1706 Since legacy and Vim9 script will be mixed and global variables will be |
|
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|
1707 shared, optional type checking is desirable. Also, type inference will avoid |
|
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|
1708 the need for specifying the type in many cases. The TypeScript syntax fits |
|
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1709 best for adding types to declarations: > |
|
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1710 var name: string # string type is specified |
|
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1711 ... |
|
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1712 name = 'John' |
|
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|
1713 const greeting = 'hello' # string type is inferred |
|
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1714 |
|
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1715 This is how we put types in a declaration: > |
|
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1716 var mylist: list<string> |
|
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1717 final mylist: list<string> = ['foo'] |
|
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1718 def Func(arg1: number, arg2: string): bool |
|
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1719 |
|
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1720 Two alternatives were considered: |
|
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1721 1. Put the type before the name, like Dart: > |
|
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1722 var list<string> mylist |
|
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1723 final list<string> mylist = ['foo'] |
|
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1724 def Func(number arg1, string arg2) bool |
|
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1725 2. Put the type after the variable name, but do not use a colon, like Go: > |
|
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1726 var mylist list<string> |
|
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|
1727 final mylist list<string> = ['foo'] |
|
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|
1728 def Func(arg1 number, arg2 string) bool |
|
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1729 |
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1730 The first is more familiar for anyone used to C or Java. The second one |
| 22565 | 1731 doesn't really have an advantage over the first, so let's discard the second. |
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1732 |
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1733 Since we use type inference the type can be left out when it can be inferred |
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1734 from the value. This means that after `var` we don't know if a type or a name |
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1735 follows. That makes parsing harder, not only for Vim but also for humans. |
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1736 Also, it will not be allowed to use a variable name that could be a type name, |
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1737 using `var string string` is too confusing. |
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1738 |
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1739 The chosen syntax, using a colon to separate the name from the type, adds |
|
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1740 punctuation, but it actually makes it easier to recognize the parts of a |
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1741 declaration. |
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1742 |
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1743 |
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1744 Expressions ~ |
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1745 |
| 22565 | 1746 Expression evaluation was already close to what other languages are doing. |
| 1747 Some details are unexpected and can be improved. For example a boolean | |
| 1748 condition would accept a string, convert it to a number and check if the | |
| 1749 number is non-zero. This is unexpected and often leads to mistakes, since | |
| 1750 text not starting with a number would be converted to zero, which is | |
| 22723 | 1751 considered false. Thus using a string for a condition would often not give an |
| 1752 error and be considered false. That is confusing. | |
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1753 |
| 23047 | 1754 In Vim9 type checking is stricter to avoid mistakes. Where a condition is |
| 22565 | 1755 used, e.g. with the `:if` command and the `||` operator, only boolean-like |
| 1756 values are accepted: | |
| 1757 true: `true`, `v:true`, `1`, `0 < 9` | |
| 1758 false: `false`, `v:false`, `0`, `0 > 9` | |
| 1759 Note that the number zero is false and the number one is true. This is more | |
| 22723 | 1760 permissive than most other languages. It was done because many builtin |
| 22565 | 1761 functions return these values. |
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1762 |
| 22565 | 1763 If you have any type of value and want to use it as a boolean, use the `!!` |
| 1764 operator: | |
| 24751 | 1765 true: `!!'text'`, `!![99]`, `!!{'x': 1}`, `!!99` |
| 22565 | 1766 false: `!!''`, `!![]`, `!!{}` |
| 1767 | |
| 1768 From a language like JavaScript we have this handy construct: > | |
| 1769 GetName() || 'unknown' | |
| 1770 However, this conflicts with only allowing a boolean for a condition. | |
| 1771 Therefore the "??" operator was added: > | |
| 1772 GetName() ?? 'unknown' | |
| 1773 Here you can explicitly express your intention to use the value as-is and not | |
| 1774 result in a boolean. This is called the |falsy-operator|. | |
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1775 |
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1776 |
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1777 Import and Export ~ |
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1778 |
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1779 A problem of legacy Vim script is that by default all functions and variables |
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1780 are global. It is possible to make them script-local, but then they are not |
| 22171 | 1781 available in other scripts. This defies the concept of a package that only |
| 1782 exports selected items and keeps the rest local. | |
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1783 |
| 21825 | 1784 In Vim9 script a mechanism very similar to the JavaScript import and export |
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1785 mechanism is supported. It is a variant to the existing `:source` command |
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1786 that works like one would expect: |
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1787 - Instead of making everything global by default, everything is script-local, |
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1788 unless exported. |
| 22171 | 1789 - When importing a script the symbols that are imported are explicitly listed, |
| 1790 avoiding name conflicts and failures if functionality is added later. | |
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1791 - The mechanism allows for writing a big, long script with a very clear API: |
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1792 the exported function(s) and class(es). |
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1793 - By using relative paths loading can be much faster for an import inside of a |
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1794 package, no need to search many directories. |
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1795 - Once an import has been used, it can be cached and loading it again can be |
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1796 avoided. |
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1797 - The Vim-specific use of "s:" to make things script-local can be dropped. |
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1798 |
| 20856 | 1799 When sourcing a Vim9 script from a legacy script, only the items defined |
| 1800 globally can be used, not the exported items. Alternatives considered: | |
| 1801 - All the exported items become available as script-local items. This makes | |
| 22171 | 1802 it uncontrollable what items get defined and likely soon leads to trouble. |
| 20856 | 1803 - Use the exported items and make them global. Disadvantage is that it's then |
| 1804 not possible to avoid name clashes in the global namespace. | |
| 1805 - Completely disallow sourcing a Vim9 script, require using `:import`. That | |
| 1806 makes it difficult to use scripts for testing, or sourcing them from the | |
| 1807 command line to try them out. | |
| 22171 | 1808 Note that you can also use `:import` in legacy Vim script, see above. |
| 20856 | 1809 |
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1810 |
| 22328 | 1811 Compiling functions early ~ |
| 1812 | |
| 1813 Functions are compiled when called or when `:defcompile` is used. Why not | |
| 1814 compile them early, so that syntax and type errors are reported early? | |
| 1815 | |
| 1816 The functions can't be compiled right away when encountered, because there may | |
| 1817 be forward references to functions defined later. Consider defining functions | |
| 1818 A, B and C, where A calls B, B calls C, and C calls A again. It's impossible | |
| 1819 to reorder the functions to avoid forward references. | |
| 1820 | |
| 1821 An alternative would be to first scan through the file to locate items and | |
| 1822 figure out their type, so that forward references are found, and only then | |
| 1823 execute the script and compile the functions. This means the script has to be | |
| 1824 parsed twice, which is slower, and some conditions at the script level, such | |
| 1825 as checking if a feature is supported, are hard to use. An attempt was made | |
| 1826 to see if it works, but it turned out to be impossible to make work nicely. | |
| 1827 | |
| 1828 It would be possible to compile all the functions at the end of the script. | |
| 1829 The drawback is that if a function never gets called, the overhead of | |
| 1830 compiling it counts anyway. Since startup speed is very important, in most | |
| 1831 cases it's better to do it later and accept that syntax and type errors are | |
| 1832 only reported then. In case these errors should be found early, e.g. when | |
| 1833 testing, the `:defcompile` command will help out. | |
| 1834 | |
| 1835 | |
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1836 Why not use an embedded language? ~ |
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1837 |
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1838 Vim supports interfaces to Perl, Python, Lua, Tcl and a few others. But |
| 22328 | 1839 these interfaces have never become widely used, for various reasons. When |
| 1840 Vim9 was designed a decision was made to make these interfaces lower priority | |
| 1841 and concentrate on Vim script. | |
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1842 |
| 22328 | 1843 Still, plugin writers may find other languages more familiar, want to use |
| 1844 existing libraries or see a performance benefit. We encourage plugin authors | |
| 1845 to write code in any language and run it as an external tool, using jobs and | |
| 1846 channels. We can try to make this easier somehow. | |
| 1847 | |
| 1848 Using an external tool also has disadvantages. An alternative is to convert | |
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1849 the tool into Vim script. For that to be possible without too much |
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1850 translation, and keeping the code fast at the same time, the constructs of the |
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1851 tool need to be supported. Since most languages support classes the lack of |
| 22171 | 1852 support for classes in Vim is then a problem. |
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1853 |
| 22328 | 1854 |
| 1855 Classes ~ | |
| 1856 | |
| 1857 Vim supports a kind-of object oriented programming by adding methods to a | |
| 1858 dictionary. With some care this can be made to work, but it does not look | |
| 1859 like real classes. On top of that, it's quite slow, because of the use of | |
| 1860 dictionaries. | |
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1861 |
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1862 The support of classes in Vim9 script is a "minimal common functionality" of |
| 22171 | 1863 class support in most languages. It works much like Java, which is the most |
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1864 popular programming language. |
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1865 |
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1866 |
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1867 |
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1868 vim:tw=78:ts=8:noet:ft=help:norl: |