Mercurial > vim
annotate runtime/doc/vim9.txt @ 26358:80b555c4aed0 v8.2.3710
patch 8.2.3710: Vim9: backtick expression expanded for :global
Commit: https://github.com/vim/vim/commit/3d2e031d4f0e1559e4a4f99de5eb2330f38f8eb5
Author: Bram Moolenaar <Bram@vim.org>
Date: Wed Dec 1 09:27:20 2021 +0000
patch 8.2.3710: Vim9: backtick expression expanded for :global
Problem: Vim9: backtick expression expanded for :global.
Solution: Check the following command.
| author | Bram Moolenaar <Bram@vim.org> |
|---|---|
| date | Wed, 01 Dec 2021 10:30:06 +0100 |
| parents | 8be6413a8e27 |
| children | c725b8e17f1f |
| rev | line source |
|---|---|
| 26304 | 1 *vim9.txt* For Vim version 8.2. Last change: 2021 Nov 22 |
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3 |
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4 VIM REFERENCE MANUAL by Bram Moolenaar |
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6 |
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7 THIS IS STILL UNDER DEVELOPMENT - ANYTHING CAN BREAK - ANYTHING CAN CHANGE |
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8 |
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9 Vim9 script commands and expressions. *Vim9* *vim9* |
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10 |
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11 Most expression help is in |eval.txt|. This file is about the new syntax and |
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12 features in Vim9 script. |
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13 |
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14 THIS IS STILL UNDER DEVELOPMENT - ANYTHING CAN BREAK - ANYTHING CAN CHANGE |
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15 |
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16 |
| 23466 | 17 1. What is Vim9 script? |Vim9-script| |
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18 2. Differences |vim9-differences| |
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19 3. New style functions |fast-functions| |
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20 4. Types |vim9-types| |
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21 5. Namespace, Import and Export |vim9script| |
| 22328 | 22 6. Future work: classes |vim9-classes| |
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23 |
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24 9. Rationale |vim9-rationale| |
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25 |
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26 ============================================================================== |
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27 |
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28 1. What is Vim9 script? *Vim9-script* |
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29 |
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30 THIS IS STILL UNDER DEVELOPMENT - ANYTHING CAN BREAK - ANYTHING CAN CHANGE |
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31 |
| 20241 | 32 Vim script has been growing over time, while preserving backwards |
| 33 compatibility. That means bad choices from the past often can't be changed | |
| 20965 | 34 and compatibility with Vi restricts possible solutions. Execution is quite |
| 20241 | 35 slow, each line is parsed every time it is executed. |
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36 |
| 20241 | 37 The main goal of Vim9 script is to drastically improve performance. This is |
| 38 accomplished by compiling commands into instructions that can be efficiently | |
| 39 executed. An increase in execution speed of 10 to 100 times can be expected. | |
| 40 | |
| 41 A secondary goal is to avoid Vim-specific constructs and get closer to | |
| 42 commonly used programming languages, such as JavaScript, TypeScript and Java. | |
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43 |
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44 The performance improvements can only be achieved by not being 100% backwards |
| 20552 | 45 compatible. For example, making function arguments available in the |
| 46 "a:" dictionary adds quite a lot of overhead. In a Vim9 function this | |
| 47 dictionary is not available. Other differences are more subtle, such as how | |
| 48 errors are handled. | |
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49 |
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50 The Vim9 script syntax and semantics are used in: |
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51 - a function defined with the `:def` command |
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52 - a script file where the first command is `vim9script` |
| 22328 | 53 - an autocommand defined in the context of the above |
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54 - a command prefixed with the `vim9cmd` command modifier |
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55 |
| 23573 | 56 When using `:function` in a Vim9 script file the legacy syntax is used, with |
| 57 the highest |scriptversion|. However, this can be confusing and is therefore | |
| 58 discouraged. | |
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59 |
| 20241 | 60 Vim9 script and legacy Vim script can be mixed. There is no requirement to |
| 22328 | 61 rewrite old scripts, they keep working as before. You may want to use a few |
| 62 `:def` functions for code that needs to be fast. | |
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63 |
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64 :vim9[cmd] {cmd} *:vim9* *:vim9cmd* |
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65 Execute {cmd} using Vim9 script syntax and semantics. |
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66 Useful when typing a command and in a legacy script or |
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67 function. |
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68 |
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69 :leg[acy] {cmd} *:leg* *:legacy* |
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70 Execute {cmd} using legacy script syntax and semantics. Only |
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71 useful in a Vim9 script or a :def function. |
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72 Note that {cmd} cannot use local variables, since it is parsed |
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73 with legacy expression syntax. |
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74 |
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75 ============================================================================== |
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76 |
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77 2. Differences from legacy Vim script *vim9-differences* |
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78 |
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79 THIS IS STILL UNDER DEVELOPMENT - ANYTHING CAN BREAK - ANYTHING CAN CHANGE |
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80 |
| 22441 | 81 Overview ~ |
| 82 | |
| 83 Brief summary of the differences you will most often encounter when using Vim9 | |
| 84 script and `:def` functions; details are below: | |
| 85 - Comments start with #, not ": > | |
| 23573 | 86 echo "hello" # comment |
| 22441 | 87 - Using a backslash for line continuation is hardly ever needed: > |
| 23573 | 88 echo "hello " |
| 22441 | 89 .. yourName |
| 90 .. ", how are you?" | |
| 91 - White space is required in many places. | |
| 92 - Assign values without `:let`, declare variables with `:var`: > | |
| 23573 | 93 var count = 0 |
| 22441 | 94 count += 3 |
| 95 - Constants can be declared with `:final` and `:const`: > | |
| 23573 | 96 final matches = [] # add matches |
| 22441 | 97 const names = ['Betty', 'Peter'] # cannot be changed |
| 98 - `:final` cannot be used as an abbreviation of `:finally`. | |
| 99 - Variables and functions are script-local by default. | |
| 100 - Functions are declared with argument types and return type: > | |
| 101 def CallMe(count: number, message: string): bool | |
| 102 - Call functions without `:call`: > | |
| 23573 | 103 writefile(['done'], 'file.txt') |
| 24751 | 104 - You cannot use `:xit`, `:t`, `:k`, `:append`, `:change`, `:insert`, `:open`, |
| 105 and `:s` or `:d` with only flags. | |
| 25973 | 106 - You cannot use curly-braces names. |
| 22441 | 107 - A range before a command must be prefixed with a colon: > |
| 23573 | 108 :%s/this/that |
| 25700 | 109 - Executing a register with "@r" does not work, you can prepend a colon or use |
| 110 `:exe`: > | |
| 111 :exe @a | |
| 23573 | 112 - Unless mentioned specifically, the highest |scriptversion| is used. |
| 22441 | 113 |
| 114 | |
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115 Comments starting with # ~ |
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116 |
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117 In legacy Vim script comments start with double quote. In Vim9 script |
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118 comments start with #. > |
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119 # declarations |
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120 var count = 0 # number of occurrences |
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121 |
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122 The reason is that a double quote can also be the start of a string. In many |
| 21825 | 123 places, especially halfway through an expression with a line break, it's hard |
| 124 to tell what the meaning is, since both a string and a comment can be followed | |
| 125 by arbitrary text. To avoid confusion only # comments are recognized. This | |
| 126 is the same as in shell scripts and Python programs. | |
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127 |
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128 In Vi # is a command to list text with numbers. In Vim9 script you can use |
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129 `:number` for that. > |
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130 101 number |
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131 |
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132 To improve readability there must be a space between a command and the # |
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133 that starts a comment: > |
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134 var name = value # comment |
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135 var name = value# error! |
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136 |
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137 Do not start a comment with #{, it looks like the legacy dictionary literal |
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138 and produces an error where this might be confusing. #{{ or #{{{ are OK, |
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139 these can be used to start a fold. |
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140 |
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141 In legacy Vim script # is also used for the alternate file name. In Vim9 |
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142 script you need to use %% instead. Instead of ## use %%% (stands for all |
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143 arguments). |
| 20115 | 144 |
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145 |
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146 Vim9 functions ~ |
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147 |
| 20241 | 148 A function defined with `:def` is compiled. Execution is many times faster, |
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149 often 10 to 100 times. |
| 20241 | 150 |
| 20552 | 151 Many errors are already found when compiling, before the function is executed. |
| 20241 | 152 The syntax is strict, to enforce code that is easy to read and understand. |
| 153 | |
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154 Compilation is done when any of these is encountered: |
| 23164 | 155 - the first time the function is called |
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156 - when the `:defcompile` command is encountered in the script after the |
| 21991 | 157 function was defined |
| 158 - `:disassemble` is used for the function. | |
| 159 - a function that is compiled calls the function or uses it as a function | |
| 25700 | 160 reference (so that the argument and return types can be checked) |
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161 *E1091* |
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162 If compilation fails it is not tried again on the next call, instead this |
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163 error is given: "E1091: Function is not compiled: {name}". |
| 24569 | 164 Compilation will fail when encountering a user command that has not been |
| 165 created yet. In this case you can call `execute()` to invoke it at runtime. > | |
| 166 def MyFunc() | |
| 167 execute('DefinedLater') | |
| 168 enddef | |
| 20552 | 169 |
| 170 `:def` has no options like `:function` does: "range", "abort", "dict" or | |
| 23164 | 171 "closure". A `:def` function always aborts on an error (unless `:silent!` was |
| 172 used for the command or inside a `:try` block), does not get a range passed | |
| 23305 | 173 cannot be a "dict" function, and can always be a closure. |
| 25700 | 174 *vim9-no-dict-function* |
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175 Later classes will be added, which replaces the "dict function" mechanism. |
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176 For now you will need to pass the dictionary explicitly: > |
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177 def DictFunc(d: dict<any>, arg: string) |
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178 echo d[arg] |
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179 enddef |
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180 var d = {item: 'value', func: DictFunc} |
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181 d.func(d, 'item') |
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182 |
| 25836 | 183 You can call a legacy dict function though: > |
| 184 func Legacy() dict | |
| 185 echo self.value | |
| 186 endfunc | |
| 187 def CallLegacy() | |
| 188 var d = {func: Legacy, value: 'text'} | |
| 189 d.func() | |
| 190 enddef | |
| 191 | |
| 20241 | 192 The argument types and return type need to be specified. The "any" type can |
| 193 be used, type checking will then be done at runtime, like with legacy | |
| 194 functions. | |
| 195 | |
| 21825 | 196 Arguments are accessed by name, without "a:", just like any other language. |
| 197 There is no "a:" dictionary or "a:000" list. | |
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198 *vim9-variable-arguments* |
| 20241 | 199 Variable arguments are defined as the last argument, with a name and have a |
| 21825 | 200 list type, similar to TypeScript. For example, a list of numbers: > |
| 22171 | 201 def MyFunc(...itemlist: list<number>) |
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202 for item in itemlist |
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203 ... |
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204 |
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205 When a function argument is optional (it has a default value) passing `v:none` |
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206 as the argument results in using the default value. This is useful when you |
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207 want to specify a value for an argument that comes after an argument that |
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208 should use its default value. Example: > |
| 25973 | 209 def MyFunc(one = 'one', last = 'last') |
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210 ... |
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211 enddef |
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212 MyFunc(v:none, 'LAST') # first argument uses default value 'one' |
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213 < |
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214 *vim9-ignored-argument* |
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215 The argument "_" (an underscore) can be used to ignore the argument. This is |
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216 most useful in callbacks where you don't need it, but do need to give an |
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217 argument to match the call. E.g. when using map() two arguments are passed, |
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218 the key and the value, to ignore the key: > |
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219 map(myList, (_, v) => v * 2) |
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220 There is no error for using the "_" argument multiple times. No type needs to |
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221 be given. |
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222 |
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223 |
| 20241 | 224 Functions and variables are script-local by default ~ |
| 20856 | 225 *vim9-scopes* |
| 20115 | 226 When using `:function` or `:def` to specify a new function at the script level |
| 227 in a Vim9 script, the function is local to the script, as if "s:" was | |
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228 prefixed. Using the "s:" prefix is optional. To define a global function or |
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229 variable the "g:" prefix must be used. For functions in an autoload script |
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230 the "name#" prefix is sufficient. > |
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231 def ThisFunction() # script-local |
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232 def s:ThisFunction() # script-local |
| 22171 | 233 def g:ThatFunction() # global |
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234 def scriptname#function() # autoload |
| 20115 | 235 |
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236 When using `:function` or `:def` to specify a nested function inside a `:def` |
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237 function, this nested function is local to the code block it is defined in. |
| 22565 | 238 In a `:def` function it is not possible to define a script-local function. It |
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239 is possible to define a global function by using the "g:" prefix. |
| 20115 | 240 |
| 241 When referring to a function and no "s:" or "g:" prefix is used, Vim will | |
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242 search for the function: |
| 22565 | 243 - in the function scope, in block scopes |
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244 - in the script scope, possibly imported |
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245 - in the list of global functions |
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246 However, it is recommended to always use "g:" to refer to a global function |
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247 for clarity. |
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248 |
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249 Since a script-local function reference can be used without "s:" the name must |
| 24278 | 250 start with an upper case letter even when using the "s:" prefix. In legacy |
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251 script "s:funcref" could be used, because it could not be referred to with |
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252 "funcref". In Vim9 script it can, therefore "s:Funcref" must be used to avoid |
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253 that the name interferes with builtin functions. |
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254 |
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255 In all cases the function must be defined before used. That is when it is |
| 22723 | 256 called, when `:defcompile` causes it to be compiled, or when code that calls |
| 257 it is being compiled (to figure out the return type). | |
| 20241 | 258 |
| 21676 | 259 The result is that functions and variables without a namespace can usually be |
| 20241 | 260 found in the script, either defined there or imported. Global functions and |
| 21676 | 261 variables could be defined anywhere (good luck finding out where!). |
| 20115 | 262 |
| 21825 | 263 Global functions can still be defined and deleted at nearly any time. In |
| 20317 | 264 Vim9 script script-local functions are defined once when the script is sourced |
| 20552 | 265 and cannot be deleted or replaced. |
| 20115 | 266 |
| 23305 | 267 When compiling a function and a function call is encountered for a function |
| 268 that is not (yet) defined, the |FuncUndefined| autocommand is not triggered. | |
| 269 You can use an autoload function if needed, or call a legacy function and have | |
| 270 |FuncUndefined| triggered there. | |
| 271 | |
| 20115 | 272 |
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273 Reloading a Vim9 script clears functions and variables by default ~ |
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274 *vim9-reload* |
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275 When loading a legacy Vim script a second time nothing is removed, the |
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276 commands will replace existing variables and functions and create new ones. |
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277 |
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278 When loading a Vim9 script a second time all existing script-local functions |
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279 and variables are deleted, thus you start with a clean slate. This is useful |
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280 if you are developing a plugin and want to try a new version. If you renamed |
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281 something you don't have to worry about the old name still hanging around. |
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282 |
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283 If you do want to keep items, use: > |
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284 vim9script noclear |
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285 |
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286 You want to use this in scripts that use a `finish` command to bail out at |
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287 some point when loaded again. E.g. when a buffer local option is set: > |
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288 vim9script noclear |
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289 setlocal completefunc=SomeFunc |
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290 if exists('*g:SomeFunc') | finish | endif |
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291 def g:SomeFunc() |
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292 .... |
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293 |
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294 |
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295 Variable declarations with :var, :final and :const ~ |
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296 *vim9-declaration* *:var* |
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297 Local variables need to be declared with `:var`. Local constants need to be |
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298 declared with `:final` or `:const`. We refer to both as "variables" in this |
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299 section. |
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300 |
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301 Variables can be local to a script, function or code block: > |
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302 vim9script |
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303 var script_var = 123 |
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304 def SomeFunc() |
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305 var func_var = script_var |
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306 if cond |
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307 var block_var = func_var |
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308 ... |
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309 |
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310 The variables are only visible in the block where they are defined and nested |
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311 blocks. Once the block ends the variable is no longer accessible: > |
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312 if cond |
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313 var inner = 5 |
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314 else |
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315 var inner = 0 |
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316 endif |
| 22171 | 317 echo inner # Error! |
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318 |
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319 The declaration must be done earlier: > |
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320 var inner: number |
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321 if cond |
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322 inner = 5 |
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323 else |
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324 inner = 0 |
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325 endif |
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326 echo inner |
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327 |
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328 To intentionally hide a variable from code that follows, a block can be |
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329 used: > |
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330 { |
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331 var temp = 'temp' |
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332 ... |
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333 } |
| 22171 | 334 echo temp # Error! |
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335 |
| 25402 | 336 This is especially useful in a user command: > |
| 337 | |
| 338 command -range Rename { | |
| 25619 | 339 var save = @a |
| 340 @a = 'some expression' | |
| 341 echo 'do something with ' .. @a | |
| 342 @a = save | |
| 343 } | |
| 25402 | 344 |
| 345 And with autocommands: > | |
| 346 | |
| 347 au BufWritePre *.go { | |
| 25619 | 348 var save = winsaveview() |
| 349 silent! exe ':%! some formatting command' | |
| 350 winrestview(save) | |
| 351 } | |
| 25402 | 352 |
| 353 Although using a :def function probably works better. | |
| 354 | |
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355 Declaring a variable with a type but without an initializer will initialize to |
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356 zero, false or empty. |
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357 |
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358 In Vim9 script `:let` cannot be used. An existing variable is assigned to |
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359 without any command. The same for global, window, tab, buffer and Vim |
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360 variables, because they are not really declared. They can also be deleted |
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361 with `:unlet`. |
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362 |
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363 `:lockvar` does not work on local variables. Use `:const` and `:final` |
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364 instead. |
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365 |
| 25619 | 366 The `exists()` and `exists_compiled()` functions do not work on local variables |
| 367 or arguments. | |
| 25402 | 368 |
| 24024 | 369 Variables, functions and function arguments cannot shadow previously defined |
| 370 or imported variables and functions in the same script file. | |
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371 Variables may shadow Ex commands, rename the variable if needed. |
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372 |
| 24387 | 373 Global variables must be prefixed with "g:", also at the script level. > |
| 19968 | 374 vim9script |
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375 var script_local = 'text' |
| 21499 | 376 g:global = 'value' |
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377 var Funcref = g:ThatFunction |
| 19968 | 378 |
| 24387 | 379 Global functions must be prefixed with "g:" when defining them, but can be |
| 380 called without "g:". > | |
| 381 vim9script | |
| 382 def g:GlobalFunc(): string | |
| 383 return 'text' | |
| 384 enddef | |
| 385 echo GlobalFunc() | |
| 386 The "g:" prefix is not needed for auto-load functions. | |
| 387 | |
| 25619 | 388 *vim9-function-defined-later* |
| 389 Although global functions can be called without the "g:" prefix, they must | |
| 390 exist when compiled. By adding the "g:" prefix the function can be defined | |
| 391 later. Example: > | |
| 392 def CallPluginFunc() | |
| 393 if exists('g:loaded_plugin') | |
| 394 g:PluginFunc() | |
| 395 endif | |
| 396 enddef | |
| 397 | |
| 398 If you would do it like this you get an error at compile time that | |
| 399 "PluginFunc" does not exist, even when "g:loaded_plugin" does not exist: > | |
| 400 def CallPluginFunc() | |
| 401 if exists('g:loaded_plugin') | |
| 402 PluginFunc() # Error - function not found | |
| 403 endif | |
| 404 enddef | |
| 405 | |
| 406 You can use exists_compiled() to avoid the error, but then the function would | |
| 407 not be called, even when "g:loaded_plugin" is defined later: > | |
| 408 def CallPluginFunc() | |
| 409 if exists_compiled('g:loaded_plugin') | |
| 410 PluginFunc() # Function may never be called | |
| 411 endif | |
| 412 enddef | |
| 413 | |
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414 Since `&opt = value` is now assigning a value to option "opt", ":&" cannot be |
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415 used to repeat a `:substitute` command. |
| 24468 | 416 *vim9-unpack-ignore* |
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417 For an unpack assignment the underscore can be used to ignore a list item, |
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418 similar to how a function argument can be ignored: > |
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419 [a, _, c] = theList |
| 24468 | 420 To ignore any remaining items: > |
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421 [a, b; _] = longList |
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422 |
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423 Declaring more than one variable at a time, using the unpack notation, is |
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424 possible. Each variable can have a type or infer it from the value: > |
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425 var [v1: number, v2] = GetValues() |
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426 Use this only when there is a list with values, declaring one variable per |
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427 line is much easier to read and change later. |
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428 |
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429 |
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430 Constants ~ |
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431 *vim9-const* *vim9-final* |
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432 How constants work varies between languages. Some consider a variable that |
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433 can't be assigned another value a constant. JavaScript is an example. Others |
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434 also make the value immutable, thus when a constant uses a list, the list |
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435 cannot be changed. In Vim9 we can use both. |
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436 |
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437 `:const` is used for making both the variable and the value a constant. Use |
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438 this for composite structures that you want to make sure will not be modified. |
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439 Example: > |
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440 const myList = [1, 2] |
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441 myList = [3, 4] # Error! |
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442 myList[0] = 9 # Error! |
| 24024 | 443 myList->add(3) # Error! |
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444 < *:final* |
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445 `:final` is used for making only the variable a constant, the value can be |
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446 changed. This is well known from Java. Example: > |
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447 final myList = [1, 2] |
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448 myList = [3, 4] # Error! |
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449 myList[0] = 9 # OK |
| 24024 | 450 myList->add(3) # OK |
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451 |
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452 It is common to write constants as ALL_CAPS, but you don't have to. |
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453 |
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454 The constant only applies to the value itself, not what it refers to. > |
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455 final females = ["Mary"] |
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456 const NAMES = [["John", "Peter"], females] |
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457 NAMES[0] = ["Jack"] # Error! |
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458 NAMES[0][0] = "Jack" # Error! |
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459 NAMES[1] = ["Emma"] # Error! |
| 23573 | 460 NAMES[1][0] = "Emma" # OK, now females[0] == "Emma" |
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461 |
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462 |
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463 Omitting :call and :eval ~ |
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464 |
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465 Functions can be called without `:call`: > |
| 22171 | 466 writefile(lines, 'file') |
| 19303 | 467 Using `:call` is still possible, but this is discouraged. |
|
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468 |
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469 A method call without `eval` is possible, so long as the start is an |
|
24128
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470 identifier or can't be an Ex command. For a function either "(" or "->" must |
|
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471 be following, without a line break. Examples: > |
|
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472 myList->add(123) |
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473 g:myList->add(123) |
|
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474 [1, 2, 3]->Process() |
|
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475 {a: 1, b: 2}->Process() |
|
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476 "foobar"->Process() |
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477 ("foobar")->Process() |
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478 'foobar'->Process() |
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479 ('foobar')->Process() |
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480 |
| 21825 | 481 In the rare case there is ambiguity between a function name and an Ex command, |
| 21676 | 482 prepend ":" to make clear you want to use the Ex command. For example, there |
| 483 is both the `:substitute` command and the `substitute()` function. When the | |
| 484 line starts with `substitute(` this will use the function. Prepend a colon to | |
| 485 use the command instead: > | |
|
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486 :substitute(pattern (replacement ( |
|
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487 |
| 25402 | 488 If the expression starts with "!" this is interpreted as a shell command, not |
| 489 negation of a condition. Thus this is a shell command: > | |
| 490 !shellCommand->something | |
| 25700 | 491 Put the expression in parentheses to use the "!" for negation: > |
| 25402 | 492 (!expression)->Method() |
| 493 | |
|
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494 Note that while variables need to be defined before they can be used, |
| 21825 | 495 functions can be called before being defined. This is required to allow |
| 496 for cyclic dependencies between functions. It is slightly less efficient, | |
|
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497 since the function has to be looked up by name. And a typo in the function |
|
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498 name will only be found when the function is called. |
|
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499 |
|
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500 |
| 19968 | 501 Omitting function() ~ |
| 502 | |
| 503 A user defined function can be used as a function reference in an expression | |
| 504 without `function()`. The argument types and return type will then be checked. | |
| 505 The function must already have been defined. > | |
| 506 | |
|
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507 var Funcref = MyFunction |
| 19968 | 508 |
| 509 When using `function()` the resulting type is "func", a function with any | |
| 25161 | 510 number of arguments and any return type (including void). The function can be |
| 511 defined later. | |
| 19968 | 512 |
| 513 | |
|
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514 Lambda using => instead of -> ~ |
| 24387 | 515 *vim9-lambda* |
|
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516 In legacy script there can be confusion between using "->" for a method call |
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517 and for a lambda. Also, when a "{" is found the parser needs to figure out if |
|
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518 it is the start of a lambda or a dictionary, which is now more complicated |
|
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519 because of the use of argument types. |
|
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520 |
|
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521 To avoid these problems Vim9 script uses a different syntax for a lambda, |
|
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522 which is similar to JavaScript: > |
|
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523 var Lambda = (arg) => expression |
|
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524 |
|
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525 No line break is allowed in the arguments of a lambda up to and including the |
| 25056 | 526 "=>" (so that Vim can tell the difference between an expression in parentheses |
| 24911 | 527 and lambda arguments). This is OK: > |
|
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528 filter(list, (k, v) => |
|
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529 v > 0) |
|
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530 This does not work: > |
|
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531 filter(list, (k, v) |
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532 => v > 0) |
|
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533 This also does not work: > |
|
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534 filter(list, (k, |
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535 v) => v > 0) |
|
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536 But you can use a backslash to concatenate the lines before parsing: > |
|
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537 filter(list, (k, |
|
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538 \ v) |
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patch 8.2.2239: Vim9: concatenating lines with backslash is inconvenient
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|
539 \ => v > 0) |
|
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|
540 < *vim9-lambda-arguments* |
|
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|
541 In legacy script a lambda could be called with any number of extra arguments, |
|
96e0b898d5b4
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changeset
|
542 there was no way to warn for not using them. In Vim9 script the number of |
|
96e0b898d5b4
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|
543 arguments must match. If you do want to accept any arguments, or any further |
|
96e0b898d5b4
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|
544 arguments, use "..._", which makes the function accept |
|
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Bram Moolenaar <Bram@vim.org>
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|
545 |vim9-variable-arguments|. Example: > |
|
96e0b898d5b4
patch 8.2.2744: Vim9: no way to explicitly ignore an argument
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diff
changeset
|
546 var Callback = (..._) => 'anything' |
|
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|
547 echo Callback(1, 2, 3) # displays "anything" |
|
96e0b898d5b4
patch 8.2.2744: Vim9: no way to explicitly ignore an argument
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diff
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|
548 |
| 24387 | 549 < *inline-function* |
|
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Bram Moolenaar <Bram@vim.org>
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550 Additionally, a lambda can contain statements in {}: > |
|
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|
551 var Lambda = (arg) => { |
|
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552 g:was_called = 'yes' |
|
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553 return expression |
|
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|
554 } |
| 24387 | 555 This can be useful for a timer, for example: > |
| 556 var count = 0 | |
| 557 var timer = timer_start(500, (_) => { | |
| 558 count += 1 | |
| 559 echom 'Handler called ' .. count | |
| 560 }, {repeat: 3}) | |
| 561 | |
|
24272
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patch 8.2.2677: Vim9: cannot use only some of the default arguments
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|
562 |
|
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|
563 The ending "}" must be at the start of a line. It can be followed by other |
|
cabed216cc2f
patch 8.2.2677: Vim9: cannot use only some of the default arguments
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|
564 characters, e.g.: > |
|
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patch 8.2.2677: Vim9: cannot use only some of the default arguments
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|
565 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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|
566 return 'value' |
|
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567 }) |
|
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|
568 No command can follow the "{", only a comment can be used there. |
|
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569 |
|
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|
570 Rationale: The "}" cannot be after a command because it would require parsing |
|
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|
571 the commands to find it. For consistency with that no command can follow the |
|
cabed216cc2f
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|
572 "{". Unfortunately this means using "() => { command }" does not work, line |
|
cabed216cc2f
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|
573 breaks are always required. |
|
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|
574 |
| 23737 | 575 *vim9-curly* |
|
23358
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patch 8.2.2222: Vim9: cannot keep script variables when reloading
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|
576 To avoid the "{" of a dictionary literal to be recognized as a statement block |
| 24024 | 577 wrap it in parentheses: > |
|
23358
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|
578 var Lambda = (arg) => ({key: 42}) |
|
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|
579 |
| 23737 | 580 Also when confused with the start of a command block: > |
| 581 ({ | |
| 582 key: value | |
| 583 })->method() | |
| 584 | |
|
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585 |
|
19999
844c7646f61b
patch 8.2.0555: Vim9: line continuation is not always needed
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|
586 Automatic line continuation ~ |
|
844c7646f61b
patch 8.2.0555: Vim9: line continuation is not always needed
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|
587 |
|
844c7646f61b
patch 8.2.0555: Vim9: line continuation is not always needed
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changeset
|
588 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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|
589 those cases there is no need to prefix the line with a backslash (see |
|
517fca70e084
patch 8.2.2239: Vim9: concatenating lines with backslash is inconvenient
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diff
changeset
|
590 |line-continuation|). For example, when a list spans multiple lines: > |
|
22391
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patch 8.2.1744: Vim9: using ":const!" is weird
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|
591 var mylist = [ |
|
19999
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patch 8.2.0555: Vim9: line continuation is not always needed
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|
592 'one', |
|
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patch 8.2.0555: Vim9: line continuation is not always needed
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593 'two', |
|
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594 ] |
|
20011
628011800942
patch 8.2.0561: Vim9: cannot split function call in multiple lines
Bram Moolenaar <Bram@vim.org>
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changeset
|
595 And when a dict spans multiple lines: > |
|
22936
00b0275ffe7f
patch 8.2.2015: Vim9: literal dict #{} is not like any other language
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|
596 var mydict = { |
|
20011
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patch 8.2.0561: Vim9: cannot split function call in multiple lines
Bram Moolenaar <Bram@vim.org>
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|
597 one: 1, |
|
628011800942
patch 8.2.0561: Vim9: cannot split function call in multiple lines
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|
598 two: 2, |
|
628011800942
patch 8.2.0561: Vim9: cannot split function call in multiple lines
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|
599 } |
|
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|
600 With a function call: > |
|
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changeset
|
601 var result = Func( |
|
20011
628011800942
patch 8.2.0561: Vim9: cannot split function call in multiple lines
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diff
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|
602 arg1, |
|
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|
603 arg2 |
|
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patch 8.2.0561: Vim9: cannot split function call in multiple lines
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|
604 ) |
|
628011800942
patch 8.2.0561: Vim9: cannot split function call in multiple lines
Bram Moolenaar <Bram@vim.org>
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|
605 |
|
20982
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patch 8.2.1042: Vim9: cannot put an operator on the next line
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changeset
|
606 For binary operators in expressions not in [], {} or () a line break is |
|
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patch 8.2.1042: Vim9: cannot put an operator on the next line
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|
607 possible just before or after the operator. For example: > |
|
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|
608 var text = lead |
|
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|
609 .. middle |
|
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patch 8.2.1042: Vim9: cannot put an operator on the next line
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|
610 .. end |
|
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patch 8.2.1744: Vim9: using ":const!" is weird
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changeset
|
611 var total = start + |
| 23573 | 612 end - |
|
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patch 8.2.0562: Vim9: cannot split an expression into multiple lines
Bram Moolenaar <Bram@vim.org>
parents:
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|
613 correction |
|
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patch 8.2.1744: Vim9: using ":const!" is weird
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|
614 var result = positive |
|
20982
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patch 8.2.1042: Vim9: cannot put an operator on the next line
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parents:
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|
615 ? PosFunc(arg) |
|
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changeset
|
616 : NegFunc(arg) |
|
20013
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patch 8.2.0562: Vim9: cannot split an expression into multiple lines
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changeset
|
617 |
| 21499 | 618 For a method call using "->" and a member using a dot, a line break is allowed |
| 619 before it: > | |
|
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|
620 var result = GetBuilder() |
| 20965 | 621 ->BuilderSetWidth(333) |
| 622 ->BuilderSetHeight(777) | |
| 623 ->BuilderBuild() | |
|
22391
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|
624 var result = MyDict |
| 21499 | 625 .member |
| 20965 | 626 |
|
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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|
627 For commands that have an argument that is a list of commands, the | character |
|
517fca70e084
patch 8.2.2239: Vim9: concatenating lines with backslash is inconvenient
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|
628 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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|
629 autocmd BufNewFile *.match if condition |
|
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patch 8.2.2239: Vim9: concatenating lines with backslash is inconvenient
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|
630 | echo 'match' |
|
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patch 8.2.2239: Vim9: concatenating lines with backslash is inconvenient
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|
631 | endif |
|
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|
632 |
| 25973 | 633 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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|
634 var lines =<< trim END |
|
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635 | this doesn't work |
|
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patch 8.2.2982: Vim9: future commands are not reserved yet
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|
636 END |
|
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|
637 Either use an empty line at the start or do not use heredoc. Or temporarily |
|
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changeset
|
638 add the "C" flag to 'cpoptions': > |
|
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patch 8.2.2982: Vim9: future commands are not reserved yet
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|
639 set cpo+=C |
|
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|
640 var lines =<< trim END |
| 25973 | 641 | this works |
|
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|
642 END |
|
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|
643 set cpo-=C |
|
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changeset
|
644 If the heredoc is inside a function 'cpoptions' must be set before :def and |
|
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changeset
|
645 restored after the :enddef. |
|
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Bram Moolenaar <Bram@vim.org>
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changeset
|
646 |
|
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changeset
|
647 In places where line continuation with a backslash is still needed, such as |
| 25161 | 648 splitting up a long Ex command, comments can start with '#\ ': > |
| 649 syn region Text | |
|
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changeset
|
650 \ start='foo' |
|
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patch 8.2.2982: Vim9: future commands are not reserved yet
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|
651 #\ comment |
|
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parents:
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diff
changeset
|
652 \ end='bar' |
| 25161 | 653 Like with legacy script '"\ ' is used. This is also needed when line |
| 654 continuation is used without a backslash and a line starts with a bar: > | |
| 655 au CursorHold * echom 'BEFORE bar' | |
| 656 #\ some comment | |
| 657 | echom 'AFTER bar' | |
| 658 < | |
| 659 *E1050* | |
|
20982
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patch 8.2.1042: Vim9: cannot put an operator on the next line
Bram Moolenaar <Bram@vim.org>
parents:
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changeset
|
660 To make it possible for the operator at the start of the line to be |
|
24888
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|
661 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
|
662 add "start" and print: > |
|
22391
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|
663 var result = start |
|
20982
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Bram Moolenaar <Bram@vim.org>
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changeset
|
664 + print |
| 21250 | 665 Like this: > |
|
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|
666 var result = start + print |
| 21250 | 667 |
|
20982
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|
668 This will assign "start" and print a line: > |
|
22391
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|
669 var result = start |
|
20982
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patch 8.2.1042: Vim9: cannot put an operator on the next line
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changeset
|
670 :+ 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
|
671 |
| 23047 | 672 Note that the colon is not required for the |+cmd| argument: > |
| 673 edit +6 fname | |
| 674 | |
|
20015
c001ee73519a
patch 8.2.0563: Vim9: cannot split a function line
Bram Moolenaar <Bram@vim.org>
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changeset
|
675 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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changeset
|
676 arguments: > |
|
c001ee73519a
patch 8.2.0563: Vim9: cannot split a function line
Bram Moolenaar <Bram@vim.org>
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changeset
|
677 def MyFunc( |
|
c001ee73519a
patch 8.2.0563: Vim9: cannot split a function line
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diff
changeset
|
678 text: string, |
|
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changeset
|
679 separator = '-' |
|
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parents:
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changeset
|
680 ): string |
|
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patch 8.2.0563: Vim9: cannot split a function line
Bram Moolenaar <Bram@vim.org>
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diff
changeset
|
681 |
| 23305 | 682 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
|
683 has been made stricter. E.g., because of the error in the first line, the |
| 23305 | 684 second line is seen as a separate command: > |
| 685 popup_create(some invalid expression, { | |
| 686 exit_cb: Func}) | |
| 687 Now "exit_cb: Func})" is actually a valid command: save any changes to the | |
| 688 file "_cb: Func})" and exit. To avoid this kind of mistake in Vim9 script | |
| 689 there must be white space between most command names and the argument. | |
| 690 | |
| 23666 | 691 However, the argument of a command that is a command won't be recognized. For |
| 692 example, after "windo echo expr" a line break inside "expr" will not be seen. | |
| 693 | |
| 23305 | 694 |
| 21250 | 695 Notes: |
| 696 - "enddef" cannot be used at the start of a continuation line, it ends the | |
| 697 current function. | |
| 698 - No line break is allowed in the LHS of an assignment. Specifically when | |
| 699 unpacking a list |:let-unpack|. This is OK: > | |
| 22171 | 700 [var1, var2] = |
| 21250 | 701 Func() |
| 702 < This does not work: > | |
| 22171 | 703 [var1, |
| 21250 | 704 var2] = |
| 705 Func() | |
| 706 - No line break is allowed in between arguments of an `:echo`, `:execute` and | |
| 707 similar commands. This is OK: > | |
| 22171 | 708 echo [1, |
| 21250 | 709 2] [3, |
| 710 4] | |
| 711 < This does not work: > | |
| 22171 | 712 echo [1, 2] |
| 21250 | 713 [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
|
714 - 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
|
715 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:
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diff
changeset
|
716 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:
19968
diff
changeset
|
717 |
| 24569 | 718 |
| 719 White space ~ | |
| 720 | |
| 721 Vim9 script enforces proper use of white space. This is no longer allowed: > | |
| 722 var name=234 # Error! | |
| 723 var name= 234 # Error! | |
| 724 var name =234 # Error! | |
| 725 There must be white space before and after the "=": > | |
| 726 var name = 234 # OK | |
| 727 White space must also be put before the # that starts a comment after a | |
| 728 command: > | |
| 729 var name = 234# Error! | |
| 730 var name = 234 # OK | |
| 731 | |
| 732 White space is required around most operators. | |
| 733 | |
| 734 White space is required in a sublist (list slice) around the ":", except at | |
| 735 the start and end: > | |
| 736 otherlist = mylist[v : count] # v:count has a different meaning | |
| 737 otherlist = mylist[:] # make a copy of the List | |
| 738 otherlist = mylist[v :] | |
| 739 otherlist = mylist[: v] | |
| 740 | |
| 741 White space is not allowed: | |
| 742 - Between a function name and the "(": > | |
| 743 Func (arg) # Error! | |
| 744 Func | |
| 745 \ (arg) # Error! | |
| 746 Func | |
| 747 (arg) # Error! | |
| 748 Func(arg) # OK | |
| 749 Func( | |
| 750 arg) # OK | |
| 751 Func( | |
| 752 arg # OK | |
| 753 ) | |
| 754 | |
| 25700 | 755 White space is not allowed in a `:set` command between the option name and a |
| 756 following "&", "!", "<", "=", "+=", "-=" or "^=". | |
| 25402 | 757 |
| 24569 | 758 |
|
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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diff
changeset
|
759 No curly braces expansion ~ |
|
94eda51ba9ba
patch 8.2.0149: maintaining a Vim9 branch separately is more work
Bram Moolenaar <Bram@vim.org>
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changeset
|
760 |
|
94eda51ba9ba
patch 8.2.0149: maintaining a Vim9 branch separately is more work
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
761 |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:
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changeset
|
762 |
|
94eda51ba9ba
patch 8.2.0149: maintaining a Vim9 branch separately is more work
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
763 |
|
22936
00b0275ffe7f
patch 8.2.2015: Vim9: literal dict #{} is not like any other language
Bram Moolenaar <Bram@vim.org>
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22723
diff
changeset
|
764 Dictionary literals ~ |
|
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
|
765 |
|
00b0275ffe7f
patch 8.2.2015: Vim9: literal dict #{} is not like any other language
Bram Moolenaar <Bram@vim.org>
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changeset
|
766 Traditionally Vim has supported dictionary literals with a {} syntax: > |
|
00b0275ffe7f
patch 8.2.2015: Vim9: literal dict #{} is not like any other language
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changeset
|
767 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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changeset
|
768 |
|
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
|
769 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:
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changeset
|
770 literal dictionaries were introduced in a backwards compatible way: > |
|
22936
00b0275ffe7f
patch 8.2.2015: Vim9: literal dict #{} is not like any other language
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changeset
|
771 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
|
772 |
|
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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changeset
|
773 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
|
774 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
|
775 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:
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diff
changeset
|
776 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:
22723
diff
changeset
|
777 uses literal keys: > |
| 23666 | 778 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:
22723
diff
changeset
|
779 |
|
23088
285cde4b8d0e
patch 8.2.2090: Vim9: dict does not accept a key in quotes
Bram Moolenaar <Bram@vim.org>
parents:
23047
diff
changeset
|
780 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:
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diff
changeset
|
781 use another character, use a single or double quoted string: > |
| 23666 | 782 var dict = {'key with space': value} |
| 783 var dict = {"key\twith\ttabs": value} | |
| 784 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>
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changeset
|
785 |
|
285cde4b8d0e
patch 8.2.2090: Vim9: dict does not accept a key in quotes
Bram Moolenaar <Bram@vim.org>
parents:
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changeset
|
786 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:
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diff
changeset
|
787 like in JavaScript: > |
| 23666 | 788 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>
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22723
diff
changeset
|
789 |
|
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
|
790 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>
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changeset
|
791 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>
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changeset
|
792 var dict = {123: 'without', [456]: 'with'} |
|
7e0d8f1cae7d
patch 8.2.2455: Vim9: key type for literal dict and indexing is inconsistent
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changeset
|
793 echo dict |
|
7e0d8f1cae7d
patch 8.2.2455: Vim9: key type for literal dict and indexing is inconsistent
Bram Moolenaar <Bram@vim.org>
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changeset
|
794 {'456': 'with', '123': 'without'} |
|
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patch 8.2.2455: Vim9: key type for literal dict and indexing is inconsistent
Bram Moolenaar <Bram@vim.org>
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changeset
|
795 |
|
22936
00b0275ffe7f
patch 8.2.2015: Vim9: literal dict #{} is not like any other language
Bram Moolenaar <Bram@vim.org>
parents:
22723
diff
changeset
|
796 |
|
23978
54b2aa1f0d42
patch 8.2.2531: Vim9: the :k command is obscure
Bram Moolenaar <Bram@vim.org>
parents:
23974
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changeset
|
797 No :xit, :t, :k, :append, :change or :insert ~ |
| 19303 | 798 |
|
21584
d0c76ce48326
patch 8.2.1342: Vim9: accidentally using "t" gives a confusing error
Bram Moolenaar <Bram@vim.org>
parents:
21550
diff
changeset
|
799 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:
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changeset
|
800 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:
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diff
changeset
|
801 Instead of `:t` you can use `:copy`. |
|
23978
54b2aa1f0d42
patch 8.2.2531: Vim9: the :k command is obscure
Bram Moolenaar <Bram@vim.org>
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23974
diff
changeset
|
802 Instead of `:k` you can use `:mark`. |
|
19181
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patch 8.2.0149: maintaining a Vim9 branch separately is more work
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parents:
diff
changeset
|
803 |
| 19303 | 804 |
| 805 Comparators ~ | |
| 806 | |
| 807 The 'ignorecase' option is not used for comparators that use strings. | |
|
19181
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Bram Moolenaar <Bram@vim.org>
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changeset
|
808 |
|
94eda51ba9ba
patch 8.2.0149: maintaining a Vim9 branch separately is more work
Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
809 |
| 24569 | 810 Abort after error ~ |
| 811 | |
| 812 In legacy script, when an error is encountered, Vim continues to execute | |
| 813 following lines. This can lead to a long sequence of errors and need to type | |
| 814 CTRL-C to stop it. In Vim9 script execution of commands stops at the first | |
| 815 error. Example: > | |
| 816 vim9script | |
| 817 var x = does-not-exist | |
| 818 echo 'not executed' | |
| 819 | |
| 820 | |
| 23666 | 821 For loop ~ |
| 822 | |
| 26304 | 823 The loop variable must not exist yet: > |
| 824 var i = 1 | |
| 825 for i in [1, 2, 3] # Error! | |
| 826 | |
| 23666 | 827 Legacy Vim script has some tricks to make a for loop over a list handle |
| 828 deleting items at the current or previous item. In Vim9 script it just uses | |
| 829 the index, if items are deleted then items in the list will be skipped. | |
| 830 Example legacy script: > | |
| 831 let l = [1, 2, 3, 4] | |
| 832 for i in l | |
| 833 echo i | |
| 834 call remove(l, index(l, i)) | |
| 835 endfor | |
| 836 Would echo: | |
| 837 1 | |
| 838 2 | |
| 839 3 | |
| 840 4 | |
| 841 In compiled Vim9 script you get: | |
| 842 1 | |
| 843 3 | |
| 844 Generally, you should not change the list that is iterated over. Make a copy | |
| 845 first if needed. | |
| 846 | |
| 847 | |
|
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Bram Moolenaar <Bram@vim.org>
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|
848 Conditions and expressions ~ |
|
94eda51ba9ba
patch 8.2.0149: maintaining a Vim9 branch separately is more work
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changeset
|
849 |
|
22500
ef8a3177edc1
patch 8.2.1798: Vim9: trinary operator condition is too permissive
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parents:
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diff
changeset
|
850 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>
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changeset
|
851 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
|
852 value legacy Vim script Vim9 script ~ |
|
ef8a3177edc1
patch 8.2.1798: Vim9: trinary operator condition is too permissive
Bram Moolenaar <Bram@vim.org>
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changeset
|
853 0 falsy falsy |
|
ef8a3177edc1
patch 8.2.1798: Vim9: trinary operator condition is too permissive
Bram Moolenaar <Bram@vim.org>
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diff
changeset
|
854 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
|
855 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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changeset
|
856 "0" falsy Error! |
|
ef8a3177edc1
patch 8.2.1798: Vim9: trinary operator condition is too permissive
Bram Moolenaar <Bram@vim.org>
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changeset
|
857 "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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changeset
|
858 "text" falsy Error! |
|
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Bram Moolenaar <Bram@vim.org>
parents:
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|
859 |
|
22500
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patch 8.2.1798: Vim9: trinary operator condition is too permissive
Bram Moolenaar <Bram@vim.org>
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changeset
|
860 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:
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diff
changeset
|
861 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:
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changeset
|
862 empty list and dict is 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
|
863 |
|
ef8a3177edc1
patch 8.2.1798: Vim9: trinary operator condition is too permissive
Bram Moolenaar <Bram@vim.org>
parents:
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changeset
|
864 type truthy when ~ |
| 23466 | 865 bool true, v:true or 1 |
|
19181
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parents:
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changeset
|
866 number non-zero |
|
94eda51ba9ba
patch 8.2.0149: maintaining a Vim9 branch separately is more work
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parents:
diff
changeset
|
867 float non-zero |
|
94eda51ba9ba
patch 8.2.0149: maintaining a Vim9 branch separately is more work
Bram Moolenaar <Bram@vim.org>
parents:
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changeset
|
868 string non-empty |
|
94eda51ba9ba
patch 8.2.0149: maintaining a Vim9 branch separately is more work
Bram Moolenaar <Bram@vim.org>
parents:
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changeset
|
869 blob non-empty |
|
94eda51ba9ba
patch 8.2.0149: maintaining a Vim9 branch separately is more work
Bram Moolenaar <Bram@vim.org>
parents:
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changeset
|
870 list non-empty (different from JavaScript) |
|
94eda51ba9ba
patch 8.2.0149: maintaining a Vim9 branch separately is more work
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changeset
|
871 dictionary non-empty (different from JavaScript) |
| 19968 | 872 func when there is a function name |
| 23466 | 873 special true or v:true |
|
19181
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parents:
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changeset
|
874 job when not NULL |
|
94eda51ba9ba
patch 8.2.0149: maintaining a Vim9 branch separately is more work
Bram Moolenaar <Bram@vim.org>
parents:
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changeset
|
875 channel when not NULL |
|
94eda51ba9ba
patch 8.2.0149: maintaining a Vim9 branch separately is more work
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parents:
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changeset
|
876 class when not NULL |
| 23466 | 877 object when not NULL (TODO: when isTrue() returns true) |
|
19181
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patch 8.2.0149: maintaining a Vim9 branch separately is more work
Bram Moolenaar <Bram@vim.org>
parents:
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changeset
|
878 |
|
22494
4c21f7f6f9e3
patch 8.2.1795: Vim9: operators && and || have a confusing result
Bram Moolenaar <Bram@vim.org>
parents:
22441
diff
changeset
|
879 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
|
880 one: > |
|
4c21f7f6f9e3
patch 8.2.1795: Vim9: operators && and || have a confusing result
Bram Moolenaar <Bram@vim.org>
parents:
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diff
changeset
|
881 1 || false == true |
|
4c21f7f6f9e3
patch 8.2.1795: Vim9: operators && and || have a confusing result
Bram Moolenaar <Bram@vim.org>
parents:
22441
diff
changeset
|
882 0 || 1 == true |
|
4c21f7f6f9e3
patch 8.2.1795: Vim9: operators && and || have a confusing result
Bram Moolenaar <Bram@vim.org>
parents:
22441
diff
changeset
|
883 0 || false == false |
|
4c21f7f6f9e3
patch 8.2.1795: Vim9: operators && and || have a confusing result
Bram Moolenaar <Bram@vim.org>
parents:
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diff
changeset
|
884 1 && true == true |
|
4c21f7f6f9e3
patch 8.2.1795: Vim9: operators && and || have a confusing result
Bram Moolenaar <Bram@vim.org>
parents:
22441
diff
changeset
|
885 0 && 1 == false |
|
4c21f7f6f9e3
patch 8.2.1795: Vim9: operators && and || have a confusing result
Bram Moolenaar <Bram@vim.org>
parents:
22441
diff
changeset
|
886 8 || 0 Error! |
|
4c21f7f6f9e3
patch 8.2.1795: Vim9: operators && and || have a confusing result
Bram Moolenaar <Bram@vim.org>
parents:
22441
diff
changeset
|
887 'yes' && 0 Error! |
|
4c21f7f6f9e3
patch 8.2.1795: Vim9: operators && and || have a confusing result
Bram Moolenaar <Bram@vim.org>
parents:
22441
diff
changeset
|
888 [] || 99 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
|
889 |
|
22494
4c21f7f6f9e3
patch 8.2.1795: Vim9: operators && and || have a confusing result
Bram Moolenaar <Bram@vim.org>
parents:
22441
diff
changeset
|
890 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
|
891 result is a boolean. "!!" can be used to turn any value into boolean: > |
| 23573 | 892 !'yes' == false |
|
22500
ef8a3177edc1
patch 8.2.1798: Vim9: trinary operator condition is too permissive
Bram Moolenaar <Bram@vim.org>
parents:
22494
diff
changeset
|
893 !![] == false |
| 23573 | 894 !![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
|
895 |
|
4c21f7f6f9e3
patch 8.2.1795: Vim9: operators && and || have a confusing result
Bram Moolenaar <Bram@vim.org>
parents:
22441
diff
changeset
|
896 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
|
897 always converted to string: > |
|
19181
94eda51ba9ba
patch 8.2.0149: maintaining a Vim9 branch separately is more work
Bram Moolenaar <Bram@vim.org>
parents:
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changeset
|
898 'hello ' .. 123 == 'hello 123' |
| 23466 | 899 'hello ' .. v:true == 'hello true' |
|
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
|
900 |
|
21771
fcf978444298
patch 8.2.1435: Vim9: always converting to string for ".." leads to mistakes
Bram Moolenaar <Bram@vim.org>
parents:
21717
diff
changeset
|
901 Simple types are string, float, special and bool. For other types |string()| |
|
fcf978444298
patch 8.2.1435: Vim9: always converting to string for ".." leads to mistakes
Bram Moolenaar <Bram@vim.org>
parents:
21717
diff
changeset
|
902 can be used. |
|
23497
2247a2ce3630
patch 8.2.2291: Vim9: cannot use "null" for v:null
Bram Moolenaar <Bram@vim.org>
parents:
23466
diff
changeset
|
903 *false* *true* *null* |
|
2247a2ce3630
patch 8.2.2291: Vim9: cannot use "null" for v:null
Bram Moolenaar <Bram@vim.org>
parents:
23466
diff
changeset
|
904 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
|
905 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
|
906 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
|
907 changed, it is only used in JSON and has no equivalent in other languages. |
|
19181
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Bram Moolenaar <Bram@vim.org>
parents:
diff
changeset
|
908 |
|
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
|
909 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
|
910 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
|
911 Example: > |
| 21825 | 912 echo 'bár'[1] |
| 913 In legacy script this results in the character 0xc3 (an illegal byte), in Vim9 | |
| 914 script this results in the string 'á'. | |
| 23573 | 915 A negative index is counting from the end, "[-1]" is the last character. |
| 23666 | 916 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
|
917 To count composing characters separately use |strcharpart()|. |
| 23573 | 918 If the index is out of range then an empty string results. |
| 919 | |
| 920 In legacy script "++var" and "--var" would be silently accepted and have no | |
| 921 effect. This is an error in Vim9 script. | |
| 922 | |
| 923 Numbers starting with zero are not considered to be octal, only numbers | |
| 924 starting with "0o" are octal: "0o744". |scriptversion-4| | |
| 21825 | 925 |
|
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Bram Moolenaar <Bram@vim.org>
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changeset
|
926 |
| 21093 | 927 What to watch out for ~ |
| 928 *vim9-gotchas* | |
| 929 Vim9 was designed to be closer to often used programming languages, but at the | |
| 930 same time tries to support the legacy Vim commands. Some compromises had to | |
| 931 be made. Here is a summary of what might be unexpected. | |
| 932 | |
| 933 Ex command ranges need to be prefixed with a colon. > | |
| 23666 | 934 -> legacy Vim: shifts the previous line to the right |
| 935 ->func() Vim9: method call in a continuation line | |
| 936 :-> Vim9: shifts the previous line to the right | |
| 21093 | 937 |
| 23666 | 938 %s/a/b legacy Vim: substitute on all lines |
| 21093 | 939 x = alongname |
| 23666 | 940 % another Vim9: modulo operator in a continuation line |
| 941 :%s/a/b Vim9: substitute on all lines | |
| 942 't legacy Vim: jump to mark t | |
| 943 'text'->func() Vim9: method call | |
| 944 :'t Vim9: jump to mark t | |
| 21093 | 945 |
| 21676 | 946 Some Ex commands can be confused with assignments in Vim9 script: > |
| 23666 | 947 g:name = value # assignment |
|
25939
377a7686a52f
patch 8.2.3503: Vim9: using g:pat:cmd is confusing
Bram Moolenaar <Bram@vim.org>
parents:
25836
diff
changeset
|
948 :g:pattern:cmd # :global command |
|
377a7686a52f
patch 8.2.3503: Vim9: using g:pat:cmd is confusing
Bram Moolenaar <Bram@vim.org>
parents:
25836
diff
changeset
|
949 |
|
377a7686a52f
patch 8.2.3503: Vim9: using g:pat:cmd is confusing
Bram Moolenaar <Bram@vim.org>
parents:
25836
diff
changeset
|
950 To avoid confusion between a `:global` or `:substitute` command and an |
|
377a7686a52f
patch 8.2.3503: Vim9: using g:pat:cmd is confusing
Bram Moolenaar <Bram@vim.org>
parents:
25836
diff
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|
951 expression or assignment, a few separators cannot be used when these commands |
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952 are abbreviated to a single character: ':', '-' and '.'. > |
| 23666 | 953 g:pattern:cmd # invalid command - ERROR |
|
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954 s:pattern:repl # invalid command - ERROR |
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955 g-pattern-cmd # invalid command - ERROR |
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956 s-pattern-repl # invalid command - ERROR |
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957 g.pattern.cmd # invalid command - ERROR |
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958 s.pattern.repl # invalid command - ERROR |
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959 |
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960 Also, there cannot be a space between the command and the separator: > |
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961 g /pattern/cmd # invalid command - ERROR |
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962 s /pattern/repl # invalid command - ERROR |
| 21676 | 963 |
| 21093 | 964 Functions defined with `:def` compile the whole function. Legacy functions |
| 965 can bail out, and the following lines are not parsed: > | |
| 966 func Maybe() | |
| 967 if !has('feature') | |
| 968 return | |
| 969 endif | |
| 970 use-feature | |
| 971 endfunc | |
| 972 Vim9 functions are compiled as a whole: > | |
| 973 def Maybe() | |
| 974 if !has('feature') | |
| 975 return | |
| 976 endif | |
| 23573 | 977 use-feature # May give a compilation error |
| 21093 | 978 enddef |
| 979 For a workaround, split it in two functions: > | |
| 980 func Maybe() | |
| 981 if has('feature') | |
| 23666 | 982 call MaybeInner() |
| 21093 | 983 endif |
| 984 endfunc | |
| 985 if has('feature') | |
| 986 def MaybeInner() | |
| 987 use-feature | |
| 988 enddef | |
| 989 endif | |
| 22171 | 990 Or put the unsupported code inside an `if` with a constant expression that |
| 21991 | 991 evaluates to false: > |
| 992 def Maybe() | |
| 993 if has('feature') | |
| 994 use-feature | |
| 995 endif | |
| 996 enddef | |
| 25619 | 997 The `exists_compiled()` function can also be used for this. |
| 998 *vim9-user-command* | |
| 23666 | 999 Another side effect of compiling a function is that the presence of a user |
| 23573 | 1000 command is checked at compile time. If the user command is defined later an |
| 1001 error will result. This works: > | |
| 1002 command -nargs=1 MyCommand echom <q-args> | |
| 1003 def Works() | |
| 1004 MyCommand 123 | |
| 1005 enddef | |
| 1006 This will give an error for "MyCommand" not being defined: > | |
| 1007 def Works() | |
| 1008 command -nargs=1 MyCommand echom <q-args> | |
| 1009 MyCommand 123 | |
| 1010 enddef | |
| 1011 A workaround is to invoke the command indirectly with `:execute`: > | |
| 1012 def Works() | |
| 1013 command -nargs=1 MyCommand echom <q-args> | |
| 1014 execute 'MyCommand 123' | |
| 1015 enddef | |
| 1016 | |
| 21991 | 1017 Note that for unrecognized commands there is no check for "|" and a following |
| 1018 command. This will give an error for missing `endif`: > | |
| 1019 def Maybe() | |
| 1020 if has('feature') | use-feature | endif | |
| 1021 enddef | |
| 21093 | 1022 |
| 23305 | 1023 Other differences ~ |
| 1024 | |
| 1025 Patterns are used like 'magic' is set, unless explicitly overruled. | |
| 1026 The 'edcompatible' option value is not used. | |
| 1027 The 'gdefault' option value is not used. | |
| 1028 | |
| 24387 | 1029 You may also find this wiki useful. It was written by an early adopter of |
| 24103 | 1030 Vim9 script: https://github.com/lacygoill/wiki/blob/master/vim/vim9.md |
| 23305 | 1031 |
| 25056 | 1032 *:++* *:--* |
| 1033 The ++ and -- commands have been added. They are very similar to adding or | |
| 1034 subtracting one: > | |
| 1035 ++var | |
| 1036 var += 1 | |
| 1037 --var | |
| 1038 var -= 1 | |
| 1039 | |
| 1040 Using ++var or --var in an expression is not supported yet. | |
| 1041 | |
|
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1042 ============================================================================== |
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1043 |
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1044 3. New style functions *fast-functions* |
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1045 |
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1046 THIS IS STILL UNDER DEVELOPMENT - ANYTHING CAN BREAK - ANYTHING CAN CHANGE |
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1047 |
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1048 *:def* |
| 21825 | 1049 :def[!] {name}([arguments])[: {return-type}] |
|
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1050 Define a new function by the name {name}. The body of |
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1051 the function follows in the next lines, until the |
|
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1052 matching `:enddef`. |
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1053 |
|
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1054 When {return-type} is omitted or is "void" the |
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1055 function is not expected to return anything. |
|
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1056 |
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1057 {arguments} is a sequence of zero or more argument |
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1058 declarations. There are three forms: |
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1059 {name}: {type} |
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1060 {name} = {value} |
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1061 {name}: {type} = {value} |
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1062 The first form is a mandatory argument, the caller |
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1063 must always provide them. |
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1064 The second and third form are optional arguments. |
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1065 When the caller omits an argument the {value} is used. |
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1066 |
| 20856 | 1067 The function will be compiled into instructions when |
| 21499 | 1068 called, or when `:disassemble` or `:defcompile` is |
| 1069 used. Syntax and type errors will be produced at that | |
| 1070 time. | |
| 20856 | 1071 |
| 21499 | 1072 It is possible to nest `:def` inside another `:def` or |
| 1073 `:function` up to about 50 levels deep. | |
| 19303 | 1074 |
|
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1075 [!] is used as with `:function`. Note that |
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1076 script-local functions cannot be deleted or redefined |
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1077 later in Vim9 script. They can only be removed by |
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1078 reloading the same script. |
|
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1079 |
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1080 *:enddef* |
| 21499 | 1081 :enddef End of a function defined with `:def`. It should be on |
| 1082 a line by its own. | |
|
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1083 |
| 24387 | 1084 You may also find this wiki useful. It was written by an early adopter of |
|
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1085 Vim9 script: https://github.com/lacygoill/wiki/blob/master/vim/vim9.md |
|
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1086 |
|
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|
1087 If the script the function is defined in is Vim9 script, then script-local |
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|
1088 variables can be accessed without the "s:" prefix. They must be defined |
| 20856 | 1089 before the function is compiled. If the script the function is defined in is |
| 1090 legacy script, then script-local variables must be accessed with the "s:" | |
| 24387 | 1091 prefix if they do not exist at the time of compiling. |
|
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1092 |
| 20552 | 1093 *:defc* *:defcompile* |
| 1094 :defc[ompile] Compile functions defined in the current script that | |
| 1095 were not compiled yet. | |
| 1096 This will report errors found during the compilation. | |
|
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1097 |
| 19404 | 1098 *:disa* *:disassemble* |
| 1099 :disa[ssemble] {func} Show the instructions generated for {func}. | |
| 1100 This is for debugging and testing. | |
|
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1101 Note that for command line completion of {func} you |
|
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1102 can prepend "s:" to find script-local functions. |
| 19404 | 1103 |
| 24911 | 1104 :disa[ssemble] profile {func} |
| 1105 Like `:disassemble` but with the instructions used for | |
| 23737 | 1106 profiling. |
| 1107 | |
| 24911 | 1108 :disa[ssemble] debug {func} |
| 1109 Like `:disassemble` but with the instructions used for | |
| 1110 debugging. | |
| 1111 | |
| 21250 | 1112 Limitations ~ |
| 1113 | |
| 1114 Local variables will not be visible to string evaluation. For example: > | |
|
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1115 def MapList(): list<string> |
|
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1116 var list = ['aa', 'bb', 'cc', 'dd'] |
| 21250 | 1117 return range(1, 2)->map('list[v:val]') |
| 1118 enddef | |
| 1119 | |
| 1120 The map argument is a string expression, which is evaluated without the | |
| 1121 function scope. Instead, use a lambda: > | |
|
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1122 def MapList(): list<string> |
|
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1123 var list = ['aa', 'bb', 'cc', 'dd'] |
| 25973 | 1124 return range(1, 2)->map((_, v) => list[v]) |
| 21250 | 1125 enddef |
| 1126 | |
|
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1127 For commands that are not compiled, such as `:edit`, backtick expansion can be |
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1128 used and it can use the local scope. Example: > |
|
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1129 def Replace() |
|
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1130 var fname = 'blah.txt' |
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1131 edit `=fname` |
| 25402 | 1132 enddef |
| 1133 | |
| 24278 | 1134 Closures defined in a loop will share the same context. For example: > |
| 1135 var flist: list<func> | |
| 25402 | 1136 for i in range(5) |
| 24278 | 1137 var inloop = i |
| 1138 flist[i] = () => inloop | |
| 1139 endfor | |
| 25402 | 1140 echo range(5)->map((i, _) => flist[i]()) |
| 1141 # Result: [4, 4, 4, 4, 4] | |
| 24278 | 1142 |
| 1143 The "inloop" variable will exist only once, all closures put in the list refer | |
| 25402 | 1144 to the same instance, which in the end will have the value 4. This is |
| 1145 efficient, also when looping many times. If you do want a separate context | |
| 1146 for each closure call a function to define it: > | |
| 1147 def GetClosure(i: number): func | |
| 1148 var infunc = i | |
| 1149 return () => infunc | |
| 24278 | 1150 enddef |
| 1151 | |
| 1152 var flist: list<func> | |
| 25402 | 1153 for i in range(5) |
| 1154 flist[i] = GetClosure(i) | |
| 24278 | 1155 endfor |
| 25402 | 1156 echo range(5)->map((i, _) => flist[i]()) |
| 1157 # Result: [0, 1, 2, 3, 4] | |
| 24278 | 1158 |
|
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1159 ============================================================================== |
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1160 |
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1161 4. Types *vim9-types* |
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1162 |
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1163 THIS IS STILL UNDER DEVELOPMENT - ANYTHING CAN BREAK - ANYTHING CAN CHANGE |
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1164 |
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1165 The following builtin types are supported: |
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1166 bool |
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1167 number |
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1168 float |
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1169 string |
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1170 blob |
|
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1171 list<{type}> |
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1172 dict<{type}> |
|
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1173 job |
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1174 channel |
| 19646 | 1175 func |
| 19968 | 1176 func: {type} |
|
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1177 func({type}, ...) |
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|
1178 func({type}, ...): {type} |
|
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1179 |
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1180 Not supported yet: |
|
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1181 tuple<a: {type}, b: {type}, ...> |
|
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1182 |
| 25161 | 1183 These types can be used in declarations, but no simple value will actually |
| 1184 have the "void" type. | |
|
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1185 |
|
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1186 There is no array type, use list<{type}> instead. For a list constant an |
|
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1187 efficient implementation is used that avoids allocating lot of small pieces of |
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1188 memory. |
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1189 |
|
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1190 A partial and function can be declared in more or less specific ways: |
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1191 func any kind of function reference, no type |
| 19968 | 1192 checking for arguments or return value |
| 25161 | 1193 func: void any number and type of arguments, no return |
| 1194 value | |
|
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1195 func: {type} any number and type of arguments with specific |
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1196 return type |
| 25161 | 1197 |
| 1198 func() function with no argument, does not return a | |
| 1199 value | |
| 1200 func(): void same | |
| 1201 func(): {type} function with no argument and return type | |
| 1202 | |
| 19968 | 1203 func({type}) function with argument type, does not return |
|
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1204 a value |
| 19968 | 1205 func({type}): {type} function with argument type and return type |
| 1206 func(?{type}) function with type of optional argument, does | |
| 1207 not return a value | |
| 1208 func(...{type}) function with type of variable number of | |
| 1209 arguments, does not return a value | |
| 1210 func({type}, ?{type}, ...{type}): {type} | |
| 1211 function with: | |
| 1212 - type of mandatory argument | |
| 1213 - type of optional argument | |
| 1214 - type of variable number of arguments | |
| 1215 - return type | |
|
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1216 |
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1217 If the return type is "void" the function does not return a value. |
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1218 |
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1219 The reference can also be a |Partial|, in which case it stores extra arguments |
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1220 and/or a dictionary, which are not visible to the caller. Since they are |
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1221 called in the same way the declaration is the same. |
|
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1222 |
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1223 Custom types can be defined with `:type`: > |
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1224 :type MyList list<string> |
|
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1225 Custom types must start with a capital letter, to avoid name clashes with |
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1226 builtin types added later, similarly to user functions. |
|
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1227 {not implemented yet} |
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1228 |
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1229 And classes and interfaces can be used as types: > |
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1230 :class MyClass |
|
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1231 :var mine: MyClass |
|
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1232 |
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1233 :interface MyInterface |
|
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1234 :var mine: MyInterface |
|
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1235 |
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1236 :class MyTemplate<Targ> |
|
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1237 :var mine: MyTemplate<number> |
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1238 :var mine: MyTemplate<string> |
|
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1239 |
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1240 :class MyInterface<Targ> |
|
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1241 :var mine: MyInterface<number> |
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1242 :var mine: MyInterface<string> |
|
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1243 {not implemented yet} |
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1244 |
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1245 |
|
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1246 Variable types and type casting ~ |
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1247 *variable-types* |
|
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1248 Variables declared in Vim9 script or in a `:def` function have a type, either |
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1249 specified explicitly or inferred from the initialization. |
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1250 |
|
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1251 Global, buffer, window and tab page variables do not have a specific type, the |
|
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1252 value can be changed at any time, possibly changing the type. Therefore, in |
|
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1253 compiled code the "any" type is assumed. |
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1254 |
|
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|
1255 This can be a problem when the "any" type is undesired and the actual type is |
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1256 expected to always be the same. For example, when declaring a list: > |
|
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1257 var l: list<number> = [1, g:two] |
| 23305 | 1258 At compile time Vim doesn't know the type of "g:two" and the expression type |
| 1259 becomes list<any>. An instruction is generated to check the list type before | |
| 1260 doing the assignment, which is a bit inefficient. | |
| 1261 *type-casting* | |
| 1262 To avoid this, use a type cast: > | |
|
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1263 var l: list<number> = [1, <number>g:two] |
| 23305 | 1264 The compiled code will then only check that "g:two" is a number and give an |
| 1265 error if it isn't. This is called type casting. | |
|
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1266 |
|
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1267 The syntax of a type cast is: "<" {type} ">". There cannot be white space |
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1268 after the "<" or before the ">" (to avoid them being confused with |
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1269 smaller-than and bigger-than operators). |
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1270 |
|
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1271 The semantics is that, if needed, a runtime type check is performed. The |
|
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1272 value is not actually changed. If you need to change the type, e.g. to change |
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1273 it to a string, use the |string()| function. Or use |str2nr()| to convert a |
|
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1274 string to a number. |
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1275 |
|
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1276 |
|
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1277 Type inference ~ |
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1278 *type-inference* |
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1279 In general: Whenever the type is clear it can be omitted. For example, when |
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1280 declaring a variable and giving it a value: > |
|
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1281 var name = 0 # infers number type |
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1282 var name = 'hello' # infers string type |
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1283 |
|
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1284 The type of a list and dictionary comes from the common type of the values. |
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1285 If the values all have the same type, that type is used for the list or |
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1286 dictionary. If there is a mix of types, the "any" type is used. > |
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1287 [1, 2, 3] list<number> |
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1288 ['a', 'b', 'c'] list<string> |
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1289 [1, 'x', 3] list<any> |
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1290 |
| 25161 | 1291 The common type of function references, if they do not all have the same |
| 1292 number of arguments, uses "(...)" to indicate the number of arguments is not | |
| 1293 specified. For example: > | |
| 1294 def Foo(x: bool) | |
| 1295 enddef | |
| 1296 def Bar(x: bool, y: bool) | |
| 1297 enddef | |
| 1298 var funclist = [Foo, Bar] | |
| 1299 echo funclist->typename() | |
| 1300 Results in: | |
| 1301 list<func(...)> | |
| 1302 | |
| 24387 | 1303 For script-local variables in Vim9 script the type is checked, also when the |
| 1304 variable was declared in a legacy function. | |
| 1305 | |
| 21991 | 1306 |
|
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1307 Stricter type checking ~ |
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1308 *type-checking* |
| 21991 | 1309 In legacy Vim script, where a number was expected, a string would be |
| 1310 automatically converted to a number. This was convenient for an actual number | |
| 24387 | 1311 such as "123", but leads to unexpected problems (and no error message) if the |
| 21991 | 1312 string doesn't start with a number. Quite often this leads to hard-to-find |
| 1313 bugs. | |
| 1314 | |
| 1315 In Vim9 script this has been made stricter. In most places it works just as | |
| 22171 | 1316 before, if the value used matches the expected type. There will sometimes be |
| 1317 an error, thus breaking backwards compatibility. For example: | |
| 21991 | 1318 - Using a number other than 0 or 1 where a boolean is expected. *E1023* |
| 25161 | 1319 - Using a string value when setting a number option. |
| 21991 | 1320 - Using a number where a string is expected. *E1024* |
| 1321 | |
| 25973 | 1322 One consequence is that the item type of a list or dict given to |map()| must |
| 24024 | 1323 not change. This will give an error in Vim9 script: > |
| 25973 | 1324 echo map([1, 2, 3], (i, v) => 'item ' .. i) |
| 24024 | 1325 E1012: Type mismatch; expected number but got string |
| 25973 | 1326 Instead use |mapnew()|: > |
| 1327 echo mapnew([1, 2, 3], (i, v) => 'item ' .. i) | |
| 25161 | 1328 ['item 0', 'item 1', 'item 2'] |
| 1329 | |
| 1330 If the item type was determined to be "any" it can change to a more specific | |
| 25973 | 1331 type. E.g. when a list of mixed types gets changed to a list of strings: > |
| 25161 | 1332 var mylist = [1, 2.0, '3'] |
| 1333 # typename(mylist) == "list<any>" | |
| 1334 map(mylist, (i, v) => 'item ' .. i) | |
| 1335 # typename(mylist) == "list<string>", no error | |
| 1336 | |
| 24024 | 1337 Same for |extend()|, use |extendnew()| instead, and for |flatten()|, use |
| 1338 |flattennew()| instead. | |
| 23573 | 1339 |
|
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1340 ============================================================================== |
|
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1341 |
|
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|
1342 5. Namespace, Import and Export |
|
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1343 *vim9script* *vim9-export* *vim9-import* |
|
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1344 |
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1345 THIS IS STILL UNDER DEVELOPMENT - ANYTHING CAN BREAK - ANYTHING CAN CHANGE |
|
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1346 |
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|
1347 A Vim9 script can be written to be imported. This means that everything in |
|
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1348 the script is local, unless exported. Those exported items, and only those |
|
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1349 items, can then be imported in another script. |
|
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1350 |
| 21991 | 1351 You can cheat by using the global namespace explicitly. We will assume here |
| 1352 that you don't do that. | |
| 1353 | |
|
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1354 |
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1355 Namespace ~ |
|
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|
1356 *vim9-namespace* |
| 19303 | 1357 To recognize a file that can be imported the `vim9script` statement must |
|
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|
1358 appear as the first statement in the file (see |vim9-mix| for an exception). |
|
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|
1359 It tells Vim to interpret the script in its own namespace, instead of the |
|
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1360 global namespace. If a file starts with: > |
|
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1361 vim9script |
|
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|
1362 var myvar = 'yes' |
|
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1363 Then "myvar" will only exist in this file. While without `vim9script` it would |
|
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1364 be available as `g:myvar` from any other script and function. |
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1365 |
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|
1366 The variables at the file level are very much like the script-local "s:" |
| 20115 | 1367 variables in legacy Vim script, but the "s:" is omitted. And they cannot be |
| 1368 deleted. | |
|
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1369 |
| 20115 | 1370 In Vim9 script the global "g:" namespace can still be used as before. And the |
| 1371 "w:", "b:" and "t:" namespaces. These have in common that variables are not | |
| 1372 declared and they can be deleted. | |
|
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1373 |
|
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1374 A side effect of `:vim9script` is that the 'cpoptions' option is set to the |
|
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|
1375 Vim default value, like with: > |
|
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|
1376 :set cpo&vim |
|
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|
1377 One of the effects is that |line-continuation| is always enabled. |
|
24150
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|
1378 The original value of 'cpoptions' is restored at the end of the script, while |
|
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|
1379 flags added or removed in the script are also added to or removed from the |
|
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|
1380 original value to get the same effect. The order of flags may change. |
|
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1381 |
|
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|
1382 *vim9-mix* |
|
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|
1383 There is one way to use both legacy and Vim9 syntax in one script file: > |
|
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|
1384 " comments may go here |
|
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|
1385 if !has('vim9script') |
|
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|
1386 " legacy script commands go here |
|
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|
1387 finish |
|
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|
1388 endif |
|
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|
1389 vim9script |
|
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|
1390 # Vim9 script commands go here |
|
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|
1391 This allows for writing a script that takes advantage of the Vim9 script |
| 24024 | 1392 syntax if possible, but will also work on a Vim version without it. |
|
23974
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|
1393 |
|
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|
1394 This can only work in two ways: |
|
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|
1395 1. The "if" statement evaluates to false, the commands up to `endif` are |
|
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|
1396 skipped and `vim9script` is then the first command actually executed. |
|
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|
1397 2. The "if" statement evaluates to true, the commands up to `endif` are |
|
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|
1398 executed and `finish` bails out before reaching `vim9script`. |
|
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|
1399 |
|
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|
1400 TODO: The "vim9script" feature does not exist yet, it will only be added once |
|
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|
1401 the Vim9 script syntax has been fully implemented. |
|
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|
1402 |
|
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1403 |
|
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|
1404 Export ~ |
|
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|
1405 *:export* *:exp* |
| 21499 | 1406 Exporting an item can be written as: > |
|
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|
1407 export const EXPORTED_CONST = 1234 |
|
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|
1408 export var someValue = ... |
|
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|
1409 export final someValue = ... |
|
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|
1410 export const someValue = ... |
|
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1411 export def MyFunc() ... |
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1412 export class MyClass ... |
|
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|
1413 export interface MyClass ... |
|
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1414 |
|
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|
1415 As this suggests, only constants, variables, `:def` functions and classes can |
|
24888
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|
1416 be exported. {not implemented yet: class, interface} |
|
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1417 |
| 20856 | 1418 *E1042* |
| 1419 `:export` can only be used in Vim9 script, at the script level. | |
|
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|
1420 |
|
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1421 |
|
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1422 Import ~ |
| 20965 | 1423 *:import* *:imp* *E1094* |
|
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1424 The exported items can be imported individually in another Vim9 script: > |
|
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|
1425 import EXPORTED_CONST from "thatscript.vim" |
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1426 import MyClass from "myclass.vim" |
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1427 |
|
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|
1428 To import multiple items at the same time: > |
|
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1429 import {someValue, MyClass} from "thatscript.vim" |
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1430 |
| 19303 | 1431 In case the name is ambiguous, another name can be specified: > |
|
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1432 import MyClass as ThatClass from "myclass.vim" |
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1433 import {someValue, MyClass as ThatClass} from "myclass.vim" |
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1434 |
|
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|
1435 To import all exported items under a specific identifier: > |
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|
1436 import * as That from 'thatscript.vim' |
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1437 |
|
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1438 Then you can use "That.EXPORTED_CONST", "That.someValue", etc. You are free |
|
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1439 to choose the name "That", but it is highly recommended to use the name of the |
| 25773 | 1440 script file to avoid confusion. Also avoid command names, because the name |
| 1441 will shadow them. | |
|
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1442 |
| 22171 | 1443 `:import` can also be used in legacy Vim script. The imported items still |
| 1444 become script-local, even when the "s:" prefix is not given. | |
| 1445 | |
|
25282
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|
1446 `:import` can not be used in a function. Imported items are intended to exist |
|
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|
1447 at the script level and only imported once. |
|
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1448 |
|
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1449 The script name after `import` can be: |
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1450 - A relative path, starting "." or "..". This finds a file relative to the |
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1451 location of the script file itself. This is useful to split up a large |
|
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1452 plugin into several files. |
|
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1453 - An absolute path, starting with "/" on Unix or "D:/" on MS-Windows. This |
| 22723 | 1454 will rarely be used. |
|
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1455 - A path not being relative or absolute. This will be found in the |
|
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1456 "import" subdirectories of 'runtimepath' entries. The name will usually be |
|
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|
1457 longer and unique, to avoid loading the wrong file. |
| 25619 | 1458 Note that "after/import" is not used. |
|
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1459 |
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1460 Once a vim9 script file has been imported, the result is cached and used the |
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1461 next time the same script is imported. It will not be read again. |
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1462 *:import-cycle* |
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1463 The `import` commands are executed when encountered. If that script (directly |
|
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1464 or indirectly) imports the current script, then items defined after the |
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1465 `import` won't be processed yet. Therefore cyclic imports can exist, but may |
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1466 result in undefined items. |
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1467 |
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1468 |
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1469 Import in an autoload script ~ |
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1470 |
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1471 For optimal startup speed, loading scripts should be postponed until they are |
| 19303 | 1472 actually needed. A recommended mechanism: |
|
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1473 |
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1474 1. In the plugin define user commands, functions and/or mappings that refer to |
|
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1475 an autoload script. > |
| 23666 | 1476 command -nargs=1 SearchForStuff searchfor#Stuff(<f-args>) |
|
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1477 |
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1478 < This goes in .../plugin/anyname.vim. "anyname.vim" can be freely chosen. |
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1479 |
| 21825 | 1480 2. In the autoload script do the actual work. You can import items from |
|
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1481 other files to split up functionality in appropriate pieces. > |
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1482 vim9script |
| 23573 | 1483 import FilterFunc from "../import/someother.vim" |
|
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1484 def searchfor#Stuff(arg: string) |
|
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|
1485 var filtered = FilterFunc(arg) |
|
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1486 ... |
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1487 < This goes in .../autoload/searchfor.vim. "searchfor" in the file name |
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1488 must be exactly the same as the prefix for the function name, that is how |
|
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1489 Vim finds the file. |
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1490 |
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1491 3. Other functionality, possibly shared between plugins, contains the exported |
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1492 items and any private items. > |
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1493 vim9script |
|
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|
1494 var localVar = 'local' |
| 22171 | 1495 export def FilterFunc(arg: string): string |
|
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1496 ... |
|
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1497 < This goes in .../import/someother.vim. |
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1498 |
|
21771
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|
1499 When compiling a `:def` function and a function in an autoload script is |
|
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|
1500 encountered, the script is not loaded until the `:def` function is called. |
|
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|
1501 |
|
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1502 |
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|
1503 Import in legacy Vim script ~ |
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1504 |
| 20856 | 1505 If an `import` statement is used in legacy Vim script, the script-local "s:" |
| 1506 namespace will be used for the imported item, even when "s:" is not specified. | |
|
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1507 |
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1508 |
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1509 ============================================================================== |
|
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1510 |
| 22328 | 1511 6. Future work: classes *vim9-classes* |
| 1512 | |
| 1513 Above "class" was mentioned a few times, but it has not been implemented yet. | |
|
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1514 Most of Vim9 script can be created without this functionality, and since |
| 22328 | 1515 implementing classes is going to be a lot of work, it is left for the future. |
| 1516 For now we'll just make sure classes can be added later. | |
| 1517 | |
| 1518 Thoughts: | |
|
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1519 - `class` / `endclass`, the whole class must be in one file |
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1520 - Class names are always CamelCase (to avoid a name clash with builtin types) |
|
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1521 - A single constructor called "constructor" |
| 22328 | 1522 - Single inheritance with `class ThisClass extends BaseClass` |
|
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1523 - `abstract class` (class with incomplete implementation) |
|
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|
1524 - `interface` / `endinterface` (abstract class without any implementation) |
| 22328 | 1525 - `class SomeClass implements SomeInterface` |
| 1526 - Generics for class: `class <Tkey, Tentry>` | |
| 1527 - Generics for function: `def <Tkey> GetLast(key: Tkey)` | |
| 1528 | |
|
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|
1529 Again, much of this is from TypeScript with a slightly different syntax. |
| 22328 | 1530 |
| 1531 Some things that look like good additions: | |
| 1532 - Use a class as an interface (like Dart) | |
| 1533 - Extend a class with methods, using an import (like Dart) | |
|
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|
1534 - Mixins |
|
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|
1535 - For testing: Mock mechanism |
| 22328 | 1536 |
| 1537 An important class that will be provided is "Promise". Since Vim is single | |
| 1538 threaded, connecting asynchronous operations is a natural way of allowing | |
| 1539 plugins to do their work without blocking the user. It's a uniform way to | |
| 1540 invoke callbacks and handle timeouts and errors. | |
| 1541 | |
|
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|
1542 Some examples: > |
|
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|
1543 |
|
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|
1544 abstract class Person |
|
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|
1545 static const prefix = 'xxx' |
|
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|
1546 var name: string |
|
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|
1547 |
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|
1548 def constructor(name: string) |
| 25402 | 1549 this.name = name |
|
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1550 enddef |
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1551 |
|
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|
1552 def display(): void |
|
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|
1553 echo name |
|
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|
1554 enddef |
|
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1555 |
|
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|
1556 abstract def find(string): Person |
|
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|
1557 endclass |
|
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1558 |
| 22328 | 1559 ============================================================================== |
| 1560 | |
|
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1561 9. Rationale *vim9-rationale* |
|
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1562 |
|
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|
1563 The :def command ~ |
|
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1564 |
|
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|
1565 Plugin writers have asked for much faster Vim script. Investigations have |
| 19303 | 1566 shown that keeping the existing semantics of function calls make this close to |
|
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1567 impossible, because of the overhead involved with calling a function, setting |
|
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|
1568 up the local function scope and executing lines. There are many details that |
|
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1569 need to be handled, such as error messages and exceptions. The need to create |
|
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1570 a dictionary for a: and l: scopes, the a:000 list and several others add too |
|
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|
1571 much overhead that cannot be avoided. |
|
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1572 |
|
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|
1573 Therefore the `:def` method to define a new-style function had to be added, |
|
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|
1574 which allows for a function with different semantics. Most things still work |
|
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|
1575 as before, but some parts do not. A new way to define a function was |
|
22391
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|
1576 considered the best way to separate the legacy style code from Vim9 style code. |
|
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1577 |
|
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|
1578 Using "def" to define a function comes from Python. Other languages use |
|
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1579 "function" which clashes with legacy Vim script. |
|
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1580 |
|
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1581 |
|
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1582 Type checking ~ |
|
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1583 |
|
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|
1584 When compiling lines of Vim commands into instructions as much as possible |
|
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1585 should be done at compile time. Postponing it to runtime makes the execution |
|
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1586 slower and means mistakes are found only later. For example, when |
|
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1587 encountering the "+" character and compiling this into a generic add |
| 23666 | 1588 instruction, at runtime the instruction would have to inspect the type of the |
| 1589 arguments and decide what kind of addition to do. And when the type is | |
| 1590 dictionary throw an error. If the types are known to be numbers then an "add | |
| 1591 number" instruction can be used, which is faster. The error can be given at | |
| 1592 compile time, no error handling is needed at runtime, since adding two numbers | |
| 1593 cannot fail. | |
|
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1594 |
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1595 The syntax for types, using <type> for compound types, is similar to Java. It |
|
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|
1596 is easy to understand and widely used. The type names are what were used in |
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|
1597 Vim before, with some additions such as "void" and "bool". |
|
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1598 |
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1599 |
| 22328 | 1600 Removing clutter and weirdness ~ |
| 20856 | 1601 |
| 22328 | 1602 Once decided that `:def` functions have different syntax than legacy functions, |
| 1603 we are free to add improvements to make the code more familiar for users who | |
| 1604 know popular programming languages. In other words: remove weird things that | |
|
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1605 only Vim does. |
| 22328 | 1606 |
| 1607 We can also remove clutter, mainly things that were done to make Vim script | |
|
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|
1608 backwards compatible with the good old Vi commands. |
| 20856 | 1609 |
| 22328 | 1610 Examples: |
| 1611 - Drop `:call` for calling a function and `:eval` for manipulating data. | |
| 1612 - Drop using a leading backslash for line continuation, automatically figure | |
| 1613 out where an expression ends. | |
| 20856 | 1614 |
| 22328 | 1615 However, this does require that some things need to change: |
| 1616 - Comments start with # instead of ", to avoid confusing them with strings. | |
|
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1617 This is good anyway, it is known from several popular languages. |
| 22328 | 1618 - Ex command ranges need to be prefixed with a colon, to avoid confusion with |
| 1619 expressions (single quote can be a string or a mark, "/" can be divide or a | |
| 1620 search command, etc.). | |
| 1621 | |
| 1622 Goal is to limit the differences. A good criteria is that when the old syntax | |
|
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1623 is accidentally used you are very likely to get an error message. |
| 20856 | 1624 |
| 1625 | |
|
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|
1626 Syntax and semantics from popular languages ~ |
|
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1627 |
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|
1628 Script writers have complained that the Vim script syntax is unexpectedly |
|
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1629 different from what they are used to. To reduce this complaint popular |
| 20856 | 1630 languages are used as an example. At the same time, we do not want to abandon |
| 1631 the well-known parts of legacy Vim script. | |
|
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1632 |
|
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1633 For many things TypeScript is followed. It's a recent language that is |
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1634 gaining popularity and has similarities with Vim script. It also has a |
| 22328 | 1635 mix of static typing (a variable always has a known value type) and dynamic |
|
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1636 typing (a variable can have different types, this changes at runtime). Since |
| 22328 | 1637 legacy Vim script is dynamically typed and a lot of existing functionality |
| 1638 (esp. builtin functions) depends on that, while static typing allows for much | |
| 1639 faster execution, we need to have this mix in Vim9 script. | |
| 1640 | |
| 22171 | 1641 There is no intention to completely match TypeScript syntax and semantics. We |
| 1642 just want to take those parts that we can use for Vim and we expect Vim users | |
| 22328 | 1643 will be happy with. TypeScript is a complex language with its own history, |
| 1644 advantages and disadvantages. To get an idea of the disadvantages read the | |
| 1645 book: "JavaScript: The Good Parts". Or find the article "TypeScript: the good | |
|
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1646 parts" and read the "Things to avoid" section. |
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1647 |
| 22328 | 1648 People familiar with other languages (Java, Python, etc.) will also find |
| 1649 things in TypeScript that they do not like or do not understand. We'll try to | |
| 1650 avoid those things. | |
|
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1651 |
|
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|
1652 Specific items from TypeScript we avoid: |
|
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|
1653 - Overloading "+", using it both for addition and string concatenation. This |
|
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|
1654 goes against legacy Vim script and often leads to mistakes. For that reason |
|
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|
1655 we will keep using ".." for string concatenation. Lua also uses ".." this |
|
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1656 way. And it allows for conversion to string for more values. |
|
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1657 - TypeScript can use an expression like "99 || 'yes'" in a condition, but |
|
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|
1658 cannot assign the value to a boolean. That is inconsistent and can be |
|
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|
1659 annoying. Vim recognizes an expression with && or || and allows using the |
|
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|
1660 result as a bool. TODO: to be reconsidered |
|
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1661 - TypeScript considers an empty string as Falsy, but an empty list or dict as |
|
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|
1662 Truthy. That is inconsistent. In Vim an empty list and dict are also |
|
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1663 Falsy. |
|
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1664 - TypeScript has various "Readonly" types, which have limited usefulness, |
|
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|
1665 since a type cast can remove the immutable nature. Vim locks the value, |
|
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1666 which is more flexible, but is only checked at runtime. |
| 22171 | 1667 |
|
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1668 |
|
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|
1669 Declarations ~ |
|
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1670 |
|
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1671 Legacy Vim script uses `:let` for every assignment, while in Vim9 declarations |
|
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1672 are used. That is different, thus it's good to use a different command: |
|
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|
1673 `:var`. This is used in many languages. The semantics might be slightly |
|
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1674 different, but it's easily recognized as a declaration. |
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1675 |
| 23047 | 1676 Using `:const` for constants is common, but the semantics varies. Some |
|
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|
1677 languages only make the variable immutable, others also make the value |
|
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1678 immutable. Since "final" is well known from Java for only making the variable |
|
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1679 immutable we decided to use that. And then `:const` can be used for making |
|
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|
1680 both immutable. This was also used in legacy Vim script and the meaning is |
|
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|
1681 almost the same. |
|
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|
1682 |
|
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|
1683 What we end up with is very similar to Dart: > |
|
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|
1684 :var name # mutable variable and value |
|
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|
1685 :final name # immutable variable, mutable value |
|
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|
1686 :const name # immutable variable and value |
|
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1687 |
|
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|
1688 Since legacy and Vim9 script will be mixed and global variables will be |
|
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|
1689 shared, optional type checking is desirable. Also, type inference will avoid |
|
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|
1690 the need for specifying the type in many cases. The TypeScript syntax fits |
|
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|
1691 best for adding types to declarations: > |
|
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1692 var name: string # string type is specified |
|
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|
1693 ... |
|
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|
1694 name = 'John' |
|
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|
1695 const greeting = 'hello' # string type is inferred |
|
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|
1696 |
|
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|
1697 This is how we put types in a declaration: > |
|
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1698 var mylist: list<string> |
|
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|
1699 final mylist: list<string> = ['foo'] |
|
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1700 def Func(arg1: number, arg2: string): bool |
|
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1701 |
|
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|
1702 Two alternatives were considered: |
|
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1703 1. Put the type before the name, like Dart: > |
|
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1704 var list<string> mylist |
|
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1705 final list<string> mylist = ['foo'] |
|
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|
1706 def Func(number arg1, string arg2) bool |
|
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1707 2. Put the type after the variable name, but do not use a colon, like Go: > |
|
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1708 var mylist list<string> |
|
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1709 final mylist list<string> = ['foo'] |
|
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|
1710 def Func(arg1 number, arg2 string) bool |
|
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1711 |
|
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1712 The first is more familiar for anyone used to C or Java. The second one |
| 22565 | 1713 doesn't really have an advantage over the first, so let's discard the second. |
|
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1714 |
|
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1715 Since we use type inference the type can be left out when it can be inferred |
|
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|
1716 from the value. This means that after `var` we don't know if a type or a name |
|
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|
1717 follows. That makes parsing harder, not only for Vim but also for humans. |
|
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|
1718 Also, it will not be allowed to use a variable name that could be a type name, |
|
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|
1719 using `var string string` is too confusing. |
|
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1720 |
|
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1721 The chosen syntax, using a colon to separate the name from the type, adds |
|
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|
1722 punctuation, but it actually makes it easier to recognize the parts of a |
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1723 declaration. |
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1724 |
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1725 |
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1726 Expressions ~ |
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1727 |
| 22565 | 1728 Expression evaluation was already close to what other languages are doing. |
| 1729 Some details are unexpected and can be improved. For example a boolean | |
| 1730 condition would accept a string, convert it to a number and check if the | |
| 1731 number is non-zero. This is unexpected and often leads to mistakes, since | |
| 1732 text not starting with a number would be converted to zero, which is | |
| 22723 | 1733 considered false. Thus using a string for a condition would often not give an |
| 1734 error and be considered false. That is confusing. | |
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1735 |
| 23047 | 1736 In Vim9 type checking is stricter to avoid mistakes. Where a condition is |
| 22565 | 1737 used, e.g. with the `:if` command and the `||` operator, only boolean-like |
| 1738 values are accepted: | |
| 1739 true: `true`, `v:true`, `1`, `0 < 9` | |
| 1740 false: `false`, `v:false`, `0`, `0 > 9` | |
| 1741 Note that the number zero is false and the number one is true. This is more | |
| 22723 | 1742 permissive than most other languages. It was done because many builtin |
| 22565 | 1743 functions return these values. |
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1744 |
| 22565 | 1745 If you have any type of value and want to use it as a boolean, use the `!!` |
| 1746 operator: | |
| 24751 | 1747 true: `!!'text'`, `!![99]`, `!!{'x': 1}`, `!!99` |
| 22565 | 1748 false: `!!''`, `!![]`, `!!{}` |
| 1749 | |
| 1750 From a language like JavaScript we have this handy construct: > | |
| 1751 GetName() || 'unknown' | |
| 1752 However, this conflicts with only allowing a boolean for a condition. | |
| 1753 Therefore the "??" operator was added: > | |
| 1754 GetName() ?? 'unknown' | |
| 1755 Here you can explicitly express your intention to use the value as-is and not | |
| 1756 result in a boolean. This is called the |falsy-operator|. | |
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1757 |
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1758 |
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1759 Import and Export ~ |
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1760 |
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1761 A problem of legacy Vim script is that by default all functions and variables |
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1762 are global. It is possible to make them script-local, but then they are not |
| 22171 | 1763 available in other scripts. This defies the concept of a package that only |
| 1764 exports selected items and keeps the rest local. | |
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1765 |
| 21825 | 1766 In Vim9 script a mechanism very similar to the JavaScript import and export |
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1767 mechanism is supported. It is a variant to the existing `:source` command |
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1768 that works like one would expect: |
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1769 - Instead of making everything global by default, everything is script-local, |
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1770 unless exported. |
| 22171 | 1771 - When importing a script the symbols that are imported are explicitly listed, |
| 1772 avoiding name conflicts and failures if functionality is added later. | |
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1773 - The mechanism allows for writing a big, long script with a very clear API: |
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1774 the exported function(s) and class(es). |
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1775 - By using relative paths loading can be much faster for an import inside of a |
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1776 package, no need to search many directories. |
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1777 - Once an import has been used, it can be cached and loading it again can be |
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1778 avoided. |
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1779 - The Vim-specific use of "s:" to make things script-local can be dropped. |
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1780 |
| 20856 | 1781 When sourcing a Vim9 script from a legacy script, only the items defined |
| 1782 globally can be used, not the exported items. Alternatives considered: | |
| 1783 - All the exported items become available as script-local items. This makes | |
| 22171 | 1784 it uncontrollable what items get defined and likely soon leads to trouble. |
| 20856 | 1785 - Use the exported items and make them global. Disadvantage is that it's then |
| 1786 not possible to avoid name clashes in the global namespace. | |
| 1787 - Completely disallow sourcing a Vim9 script, require using `:import`. That | |
| 1788 makes it difficult to use scripts for testing, or sourcing them from the | |
| 1789 command line to try them out. | |
| 22171 | 1790 Note that you can also use `:import` in legacy Vim script, see above. |
| 20856 | 1791 |
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1792 |
| 22328 | 1793 Compiling functions early ~ |
| 1794 | |
| 1795 Functions are compiled when called or when `:defcompile` is used. Why not | |
| 1796 compile them early, so that syntax and type errors are reported early? | |
| 1797 | |
| 1798 The functions can't be compiled right away when encountered, because there may | |
| 1799 be forward references to functions defined later. Consider defining functions | |
| 1800 A, B and C, where A calls B, B calls C, and C calls A again. It's impossible | |
| 1801 to reorder the functions to avoid forward references. | |
| 1802 | |
| 1803 An alternative would be to first scan through the file to locate items and | |
| 1804 figure out their type, so that forward references are found, and only then | |
| 1805 execute the script and compile the functions. This means the script has to be | |
| 1806 parsed twice, which is slower, and some conditions at the script level, such | |
| 1807 as checking if a feature is supported, are hard to use. An attempt was made | |
| 1808 to see if it works, but it turned out to be impossible to make work nicely. | |
| 1809 | |
| 1810 It would be possible to compile all the functions at the end of the script. | |
| 1811 The drawback is that if a function never gets called, the overhead of | |
| 1812 compiling it counts anyway. Since startup speed is very important, in most | |
| 1813 cases it's better to do it later and accept that syntax and type errors are | |
| 1814 only reported then. In case these errors should be found early, e.g. when | |
| 1815 testing, the `:defcompile` command will help out. | |
| 1816 | |
| 1817 | |
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1818 Why not use an embedded language? ~ |
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1819 |
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1820 Vim supports interfaces to Perl, Python, Lua, Tcl and a few others. But |
| 22328 | 1821 these interfaces have never become widely used, for various reasons. When |
| 1822 Vim9 was designed a decision was made to make these interfaces lower priority | |
| 1823 and concentrate on Vim script. | |
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1824 |
| 22328 | 1825 Still, plugin writers may find other languages more familiar, want to use |
| 1826 existing libraries or see a performance benefit. We encourage plugin authors | |
| 1827 to write code in any language and run it as an external tool, using jobs and | |
| 1828 channels. We can try to make this easier somehow. | |
| 1829 | |
| 1830 Using an external tool also has disadvantages. An alternative is to convert | |
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1831 the tool into Vim script. For that to be possible without too much |
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1832 translation, and keeping the code fast at the same time, the constructs of the |
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1833 tool need to be supported. Since most languages support classes the lack of |
| 22171 | 1834 support for classes in Vim is then a problem. |
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1835 |
| 22328 | 1836 |
| 1837 Classes ~ | |
| 1838 | |
| 1839 Vim supports a kind-of object oriented programming by adding methods to a | |
| 1840 dictionary. With some care this can be made to work, but it does not look | |
| 1841 like real classes. On top of that, it's quite slow, because of the use of | |
| 1842 dictionaries. | |
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1843 |
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1844 The support of classes in Vim9 script is a "minimal common functionality" of |
| 22171 | 1845 class support in most languages. It works much like Java, which is the most |
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1846 popular programming language. |
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1847 |
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1848 |
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1849 |
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1850 vim:tw=78:ts=8:noet:ft=help:norl: |