Mercurial > vim
annotate runtime/doc/vim9.txt @ 23827:7e0d8f1cae7d v8.2.2455
patch 8.2.2455: Vim9: key type for literal dict and indexing is inconsistent
Commit: https://github.com/vim/vim/commit/2e5910bfbb05957c10c9c69756dfa342557e9a8b
Author: Bram Moolenaar <Bram@vim.org>
Date: Wed Feb 3 17:41:24 2021 +0100
patch 8.2.2455: Vim9: key type for literal dict and indexing is inconsistent
Problem: Vim9: key type that can be used for literal dict and indexing is
inconsistent.
Solution: Allow using number and bool as key for a literal dict. (#7771)
| author | Bram Moolenaar <Bram@vim.org> |
|---|---|
| date | Wed, 03 Feb 2021 17:45:06 +0100 |
| parents | 34b4eb3a8458 |
| children | 5b37a0bf7e3a |
| rev | line source |
|---|---|
| 23737 | 1 *vim9.txt* For Vim version 8.2. Last change: 2021 Jan 23 |
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4 VIM REFERENCE MANUAL by Bram Moolenaar |
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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 |
| 23573 | 55 When using `:function` in a Vim9 script file the legacy syntax is used, with |
| 56 the highest |scriptversion|. However, this can be confusing and is therefore | |
| 57 discouraged. | |
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58 |
| 20241 | 59 Vim9 script and legacy Vim script can be mixed. There is no requirement to |
| 22328 | 60 rewrite old scripts, they keep working as before. You may want to use a few |
| 61 `:def` functions for code that needs to be fast. | |
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62 |
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63 ============================================================================== |
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64 |
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65 2. Differences from legacy Vim script *vim9-differences* |
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66 |
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67 THIS IS STILL UNDER DEVELOPMENT - ANYTHING CAN BREAK - ANYTHING CAN CHANGE |
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68 |
| 22441 | 69 Overview ~ |
| 70 | |
| 71 Brief summary of the differences you will most often encounter when using Vim9 | |
| 72 script and `:def` functions; details are below: | |
| 73 - Comments start with #, not ": > | |
| 23573 | 74 echo "hello" # comment |
| 22441 | 75 - Using a backslash for line continuation is hardly ever needed: > |
| 23573 | 76 echo "hello " |
| 22441 | 77 .. yourName |
| 78 .. ", how are you?" | |
| 79 - White space is required in many places. | |
| 80 - Assign values without `:let`, declare variables with `:var`: > | |
| 23573 | 81 var count = 0 |
| 22441 | 82 count += 3 |
| 83 - Constants can be declared with `:final` and `:const`: > | |
| 23573 | 84 final matches = [] # add matches |
| 22441 | 85 const names = ['Betty', 'Peter'] # cannot be changed |
| 86 - `:final` cannot be used as an abbreviation of `:finally`. | |
| 87 - Variables and functions are script-local by default. | |
| 88 - Functions are declared with argument types and return type: > | |
| 89 def CallMe(count: number, message: string): bool | |
| 90 - Call functions without `:call`: > | |
| 23573 | 91 writefile(['done'], 'file.txt') |
| 22441 | 92 - You cannot use `:xit`, `:t`, `:append`, `:change`, `:insert` or curly-braces |
| 93 names. | |
| 94 - A range before a command must be prefixed with a colon: > | |
| 23573 | 95 :%s/this/that |
| 96 - Unless mentioned specifically, the highest |scriptversion| is used. | |
| 22441 | 97 |
| 98 | |
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99 Comments starting with # ~ |
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100 |
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101 In legacy Vim script comments start with double quote. In Vim9 script |
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102 comments start with #. > |
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103 # declarations |
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104 var count = 0 # number of occurrences |
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105 |
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106 The reason is that a double quote can also be the start of a string. In many |
| 21825 | 107 places, especially halfway through an expression with a line break, it's hard |
| 108 to tell what the meaning is, since both a string and a comment can be followed | |
| 109 by arbitrary text. To avoid confusion only # comments are recognized. This | |
| 110 is the same as in shell scripts and Python programs. | |
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111 |
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112 In Vi # is a command to list text with numbers. In Vim9 script you can use |
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113 `:number` for that. > |
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114 101 number |
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115 |
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116 To improve readability there must be a space between a command and the # |
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117 that starts a comment: > |
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118 var name = value # comment |
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119 var name = value# error! |
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120 |
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121 In legacy Vim script # is also used for the alternate file name. In Vim9 |
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122 script you need to use %% instead. Instead of ## use %%% (stands for all |
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123 arguments). |
| 20115 | 124 |
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125 |
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126 Vim9 functions ~ |
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127 |
| 20241 | 128 A function defined with `:def` is compiled. Execution is many times faster, |
| 129 often 10x to 100x times. | |
| 130 | |
| 20552 | 131 Many errors are already found when compiling, before the function is executed. |
| 20241 | 132 The syntax is strict, to enforce code that is easy to read and understand. |
| 133 | |
| 23164 | 134 Compilation is done when either of these is encountered: |
| 135 - the first time the function is called | |
| 21991 | 136 - when the `:defcompile` command is encountered in the script where the |
| 137 function was defined | |
| 138 - `:disassemble` is used for the function. | |
| 139 - a function that is compiled calls the function or uses it as a function | |
| 140 reference | |
| 20552 | 141 |
| 142 `:def` has no options like `:function` does: "range", "abort", "dict" or | |
| 23164 | 143 "closure". A `:def` function always aborts on an error (unless `:silent!` was |
| 144 used for the command or inside a `:try` block), does not get a range passed | |
| 23305 | 145 cannot be a "dict" function, and can always be a closure. |
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146 |
| 20241 | 147 The argument types and return type need to be specified. The "any" type can |
| 148 be used, type checking will then be done at runtime, like with legacy | |
| 149 functions. | |
| 150 | |
| 21825 | 151 Arguments are accessed by name, without "a:", just like any other language. |
| 152 There is no "a:" dictionary or "a:000" list. | |
| 20241 | 153 |
| 154 Variable arguments are defined as the last argument, with a name and have a | |
| 21825 | 155 list type, similar to TypeScript. For example, a list of numbers: > |
| 22171 | 156 def MyFunc(...itemlist: list<number>) |
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157 for item in itemlist |
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158 ... |
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159 |
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160 |
| 20241 | 161 Functions and variables are script-local by default ~ |
| 20856 | 162 *vim9-scopes* |
| 20115 | 163 When using `:function` or `:def` to specify a new function at the script level |
| 164 in a Vim9 script, the function is local to the script, as if "s:" was | |
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165 prefixed. Using the "s:" prefix is optional. To define a global function or |
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166 variable the "g:" prefix must be used. For functions in an autoload script |
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167 the "name#" prefix is sufficient. > |
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168 def ThisFunction() # script-local |
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169 def s:ThisFunction() # script-local |
| 22171 | 170 def g:ThatFunction() # global |
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171 def scriptname#function() # autoload |
| 20115 | 172 |
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173 When using `:function` or `:def` to specify a nested function inside a `:def` |
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174 function, this nested function is local to the code block it is defined in. |
| 22565 | 175 In a `:def` function it is not possible to define a script-local function. It |
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176 is possible to define a global function by using the "g:" prefix. |
| 20115 | 177 |
| 178 When referring to a function and no "s:" or "g:" prefix is used, Vim will | |
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179 search for the function: |
| 22565 | 180 - in the function scope, in block scopes |
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181 - in the script scope, possibly imported |
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182 - in the list of global functions |
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183 However, it is recommended to always use "g:" to refer to a global function |
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184 for clarity. |
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185 |
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186 In all cases the function must be defined before used. That is when it is |
| 22723 | 187 called, when `:defcompile` causes it to be compiled, or when code that calls |
| 188 it is being compiled (to figure out the return type). | |
| 20241 | 189 |
| 21676 | 190 The result is that functions and variables without a namespace can usually be |
| 20241 | 191 found in the script, either defined there or imported. Global functions and |
| 21676 | 192 variables could be defined anywhere (good luck finding out where!). |
| 20115 | 193 |
| 21825 | 194 Global functions can still be defined and deleted at nearly any time. In |
| 20317 | 195 Vim9 script script-local functions are defined once when the script is sourced |
| 20552 | 196 and cannot be deleted or replaced. |
| 20115 | 197 |
| 23305 | 198 When compiling a function and a function call is encountered for a function |
| 199 that is not (yet) defined, the |FuncUndefined| autocommand is not triggered. | |
| 200 You can use an autoload function if needed, or call a legacy function and have | |
| 201 |FuncUndefined| triggered there. | |
| 202 | |
| 20115 | 203 |
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204 Reloading a Vim9 script clears functions and variables by default ~ |
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205 *vim9-reload* |
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206 When loading a legacy Vim script a second time nothing is removed, the |
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207 commands will replace existing variables and functions and create new ones. |
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208 |
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209 When loading a Vim9 script a second time all existing script-local functions |
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210 and variables are deleted, thus you start with a clean slate. This is useful |
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211 if you are developing a plugin and want to try a new version. If you renamed |
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212 something you don't have to worry about the old name still hanging around. |
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213 |
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214 If you do want to keep items, use: > |
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215 vim9script noclear |
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216 |
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217 You want to use this in scripts that use a `finish` command to bail out at |
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218 some point when loaded again. E.g. when a buffer local option is set: > |
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219 vim9script noclear |
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220 setlocal completefunc=SomeFunc |
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221 if exists('*g:SomeFunc') | finish | endif |
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222 def g:SomeFunc() |
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223 .... |
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224 |
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225 |
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226 Variable declarations with :var, :final and :const ~ |
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227 *vim9-declaration* *:var* |
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228 Local variables need to be declared with `:var`. Local constants need to be |
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229 declared with `:final` or `:const`. We refer to both as "variables" in this |
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230 section. |
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231 |
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232 Variables can be local to a script, function or code block: > |
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233 vim9script |
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234 var script_var = 123 |
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235 def SomeFunc() |
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236 var func_var = script_var |
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237 if cond |
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238 var block_var = func_var |
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239 ... |
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240 |
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241 The variables are only visible in the block where they are defined and nested |
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242 blocks. Once the block ends the variable is no longer accessible: > |
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243 if cond |
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244 var inner = 5 |
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245 else |
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246 var inner = 0 |
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247 endif |
| 22171 | 248 echo inner # Error! |
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249 |
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250 The declaration must be done earlier: > |
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251 var inner: number |
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252 if cond |
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253 inner = 5 |
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254 else |
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255 inner = 0 |
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256 endif |
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257 echo inner |
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258 |
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259 To intentionally hide a variable from code that follows, a block can be |
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260 used: > |
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261 { |
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262 var temp = 'temp' |
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263 ... |
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264 } |
| 22171 | 265 echo temp # Error! |
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266 |
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267 Declaring a variable with a type but without an initializer will initialize to |
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268 zero, false or empty. |
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269 |
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270 In Vim9 script `:let` cannot be used. An existing variable is assigned to |
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271 without any command. The same for global, window, tab, buffer and Vim |
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272 variables, because they are not really declared. They can also be deleted |
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273 with `:unlet`. |
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274 |
| 21676 | 275 Variables and functions cannot shadow previously defined or imported variables |
| 276 and functions. | |
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277 Variables may shadow Ex commands, rename the variable if needed. |
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278 |
| 20241 | 279 Global variables and user defined functions must be prefixed with "g:", also |
| 280 at the script level. > | |
| 19968 | 281 vim9script |
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282 var script_local = 'text' |
| 21499 | 283 g:global = 'value' |
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284 var Funcref = g:ThatFunction |
| 19968 | 285 |
|
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286 Since `&opt = value` is now assigning a value to option "opt", ":&" cannot be |
|
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287 used to repeat a `:substitute` command. |
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288 |
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289 |
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290 Constants ~ |
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291 *vim9-const* *vim9-final* |
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292 How constants work varies between languages. Some consider a variable that |
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293 can't be assigned another value a constant. JavaScript is an example. Others |
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294 also make the value immutable, thus when a constant uses a list, the list |
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295 cannot be changed. In Vim9 we can use both. |
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296 |
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297 `:const` is used for making both the variable and the value a constant. Use |
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298 this for composite structures that you want to make sure will not be modified. |
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299 Example: > |
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300 const myList = [1, 2] |
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301 myList = [3, 4] # Error! |
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302 myList[0] = 9 # Error! |
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303 muList->add(3) # Error! |
|
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304 < *:final* |
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305 `:final` is used for making only the variable a constant, the value can be |
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306 changed. This is well known from Java. Example: > |
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307 final myList = [1, 2] |
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308 myList = [3, 4] # Error! |
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309 myList[0] = 9 # OK |
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310 muList->add(3) # OK |
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311 |
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312 It is common to write constants as ALL_CAPS, but you don't have to. |
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313 |
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314 The constant only applies to the value itself, not what it refers to. > |
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315 final females = ["Mary"] |
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316 const NAMES = [["John", "Peter"], females] |
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317 NAMES[0] = ["Jack"] # Error! |
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318 NAMES[0][0] = "Jack" # Error! |
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319 NAMES[1] = ["Emma"] # Error! |
| 23573 | 320 NAMES[1][0] = "Emma" # OK, now females[0] == "Emma" |
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321 |
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322 < *E1092* |
| 21499 | 323 Declaring more than one variable at a time, using the unpack notation, is |
| 324 currently not supported: > | |
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325 var [v1, v2] = GetValues() # Error! |
| 21499 | 326 That is because the type needs to be inferred from the list item type, which |
| 327 isn't that easy. | |
| 328 | |
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329 |
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330 Omitting :call and :eval ~ |
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331 |
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332 Functions can be called without `:call`: > |
| 22171 | 333 writefile(lines, 'file') |
| 19303 | 334 Using `:call` is still possible, but this is discouraged. |
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335 |
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336 A method call without `eval` is possible, so long as the start is an |
|
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337 identifier or can't be an Ex command. Examples: > |
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338 myList->add(123) |
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339 g:myList->add(123) |
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340 [1, 2, 3]->Process() |
|
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341 {a: 1, b: 2}->Process() |
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342 "foobar"->Process() |
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343 ("foobar")->Process() |
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344 'foobar'->Process() |
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345 ('foobar')->Process() |
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346 |
| 21825 | 347 In the rare case there is ambiguity between a function name and an Ex command, |
| 21676 | 348 prepend ":" to make clear you want to use the Ex command. For example, there |
| 349 is both the `:substitute` command and the `substitute()` function. When the | |
| 350 line starts with `substitute(` this will use the function. Prepend a colon to | |
| 351 use the command instead: > | |
|
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352 :substitute(pattern (replacement ( |
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353 |
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354 Note that while variables need to be defined before they can be used, |
| 21825 | 355 functions can be called before being defined. This is required to allow |
| 356 for cyclic dependencies between functions. It is slightly less efficient, | |
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357 since the function has to be looked up by name. And a typo in the function |
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358 name will only be found when the function is called. |
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359 |
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360 |
| 19968 | 361 Omitting function() ~ |
| 362 | |
| 363 A user defined function can be used as a function reference in an expression | |
| 364 without `function()`. The argument types and return type will then be checked. | |
| 365 The function must already have been defined. > | |
| 366 | |
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367 var Funcref = MyFunction |
| 19968 | 368 |
| 369 When using `function()` the resulting type is "func", a function with any | |
| 370 number of arguments and any return type. The function can be defined later. | |
| 371 | |
| 372 | |
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373 Lambda using => instead of -> ~ |
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374 |
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375 In legacy script there can be confusion between using "->" for a method call |
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376 and for a lambda. Also, when a "{" is found the parser needs to figure out if |
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377 it is the start of a lambda or a dictionary, which is now more complicated |
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378 because of the use of argument types. |
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379 |
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380 To avoid these problems Vim9 script uses a different syntax for a lambda, |
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381 which is similar to Javascript: > |
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382 var Lambda = (arg) => expression |
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383 |
|
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384 No line break is allowed in the arguments of a lambda up to and including the |
|
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385 "=>". This is OK: > |
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386 filter(list, (k, v) => |
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387 v > 0) |
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388 This does not work: > |
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389 filter(list, (k, v) |
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390 => v > 0) |
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391 This also does not work: > |
|
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392 filter(list, (k, |
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393 v) => v > 0) |
|
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394 But you can use a backslash to concatenate the lines before parsing: > |
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395 filter(list, (k, |
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396 \ v) |
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397 \ => v > 0) |
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398 |
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399 Additionally, a lambda can contain statements in {}: > |
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400 var Lambda = (arg) => { |
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401 g:was_called = 'yes' |
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402 return expression |
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403 } |
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404 NOT IMPLEMENTED YET |
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405 |
| 23737 | 406 *vim9-curly* |
|
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407 To avoid the "{" of a dictionary literal to be recognized as a statement block |
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408 wrap it in parenthesis: > |
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409 var Lambda = (arg) => ({key: 42}) |
|
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410 |
| 23737 | 411 Also when confused with the start of a command block: > |
| 412 ({ | |
| 413 key: value | |
| 414 })->method() | |
| 415 | |
|
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416 |
|
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417 Automatic line continuation ~ |
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418 |
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419 In many cases it is obvious that an expression continues on the next line. In |
|
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420 those cases there is no need to prefix the line with a backslash (see |
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421 |line-continuation|). For example, when a list spans multiple lines: > |
|
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422 var mylist = [ |
|
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423 'one', |
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424 'two', |
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425 ] |
|
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426 And when a dict spans multiple lines: > |
|
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427 var mydict = { |
|
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428 one: 1, |
|
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429 two: 2, |
|
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430 } |
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431 Function call: > |
|
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432 var result = Func( |
|
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433 arg1, |
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434 arg2 |
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435 ) |
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436 |
|
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437 For binary operators in expressions not in [], {} or () a line break is |
|
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438 possible just before or after the operator. For example: > |
|
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439 var text = lead |
|
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440 .. middle |
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441 .. end |
|
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442 var total = start + |
| 23573 | 443 end - |
|
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444 correction |
|
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445 var result = positive |
|
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446 ? PosFunc(arg) |
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447 : NegFunc(arg) |
|
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448 |
| 21499 | 449 For a method call using "->" and a member using a dot, a line break is allowed |
| 450 before it: > | |
|
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451 var result = GetBuilder() |
| 20965 | 452 ->BuilderSetWidth(333) |
| 453 ->BuilderSetHeight(777) | |
| 454 ->BuilderBuild() | |
|
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455 var result = MyDict |
| 21499 | 456 .member |
| 20965 | 457 |
|
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458 For commands that have an argument that is a list of commands, the | character |
|
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459 at the start of the line indicates line continuation: > |
|
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460 autocmd BufNewFile *.match if condition |
|
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461 | echo 'match' |
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462 | endif |
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463 |
|
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464 < *E1050* |
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465 To make it possible for the operator at the start of the line to be |
| 21250 | 466 recognized, it is required to put a colon before a range. This will add |
|
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467 "start" and print: > |
|
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468 var result = start |
|
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469 + print |
| 21250 | 470 Like this: > |
|
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471 var result = start + print |
| 21250 | 472 |
|
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473 This will assign "start" and print a line: > |
|
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474 var result = start |
|
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475 :+ print |
|
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476 |
| 23047 | 477 Note that the colon is not required for the |+cmd| argument: > |
| 478 edit +6 fname | |
| 479 | |
|
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480 It is also possible to split a function header over multiple lines, in between |
|
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481 arguments: > |
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482 def MyFunc( |
|
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483 text: string, |
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484 separator = '-' |
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485 ): string |
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486 |
| 23305 | 487 Since a continuation line cannot be easily recognized the parsing of commands |
|
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488 has been made stricter. E.g., because of the error in the first line, the |
| 23305 | 489 second line is seen as a separate command: > |
| 490 popup_create(some invalid expression, { | |
| 491 exit_cb: Func}) | |
| 492 Now "exit_cb: Func})" is actually a valid command: save any changes to the | |
| 493 file "_cb: Func})" and exit. To avoid this kind of mistake in Vim9 script | |
| 494 there must be white space between most command names and the argument. | |
| 495 | |
| 23666 | 496 However, the argument of a command that is a command won't be recognized. For |
| 497 example, after "windo echo expr" a line break inside "expr" will not be seen. | |
| 498 | |
| 23305 | 499 |
| 21250 | 500 Notes: |
| 501 - "enddef" cannot be used at the start of a continuation line, it ends the | |
| 502 current function. | |
| 503 - No line break is allowed in the LHS of an assignment. Specifically when | |
| 504 unpacking a list |:let-unpack|. This is OK: > | |
| 22171 | 505 [var1, var2] = |
| 21250 | 506 Func() |
| 507 < This does not work: > | |
| 22171 | 508 [var1, |
| 21250 | 509 var2] = |
| 510 Func() | |
| 511 - No line break is allowed in between arguments of an `:echo`, `:execute` and | |
| 512 similar commands. This is OK: > | |
| 22171 | 513 echo [1, |
| 21250 | 514 2] [3, |
| 515 4] | |
| 516 < This does not work: > | |
| 22171 | 517 echo [1, 2] |
| 21250 | 518 [3, 4] |
|
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519 |
|
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520 No curly braces expansion ~ |
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521 |
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522 |curly-braces-names| cannot be used. |
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523 |
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524 |
|
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525 Dictionary literals ~ |
|
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526 |
|
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527 Traditionally Vim has supported dictionary literals with a {} syntax: > |
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528 let dict = {'key': value} |
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529 |
|
23088
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530 Later it became clear that using a simple text key is very common, thus |
|
285cde4b8d0e
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|
531 literal dictionaries were introduced in a backwards compatible way: > |
|
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532 let dict = #{key: value} |
|
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533 |
|
23088
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534 However, this #{} syntax is unlike any existing language. As it turns out |
|
285cde4b8d0e
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|
535 that using a literal key is much more common than using an expression, and |
|
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|
536 considering that JavaScript uses this syntax, using the {} form for dictionary |
|
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537 literals is considered a much more useful syntax. In Vim9 script the {} form |
|
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|
538 uses literal keys: > |
| 23666 | 539 var dict = {key: value} |
|
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|
540 |
|
23088
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changeset
|
541 This works for alphanumeric characters, underscore and dash. If you want to |
|
285cde4b8d0e
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|
542 use another character, use a single or double quoted string: > |
| 23666 | 543 var dict = {'key with space': value} |
| 544 var dict = {"key\twith\ttabs": value} | |
| 545 var dict = {'': value} # empty key | |
|
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|
546 |
|
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547 In case the key needs to be an expression, square brackets can be used, just |
|
285cde4b8d0e
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548 like in JavaScript: > |
| 23666 | 549 var dict = {["key" .. nr]: value} |
|
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550 |
|
23827
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|
551 The key type can be string, number, bool or float. Other types result in an |
|
7e0d8f1cae7d
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552 error. A number can be given with and without the []: > |
|
7e0d8f1cae7d
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|
553 var dict = {123: 'without', [456]: 'with'} |
|
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|
554 echo dict |
|
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555 {'456': 'with', '123': 'without'} |
|
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|
556 |
|
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|
557 |
|
21584
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|
558 No :xit, :t, :append, :change or :insert ~ |
| 19303 | 559 |
|
21584
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|
560 These commands are too easily confused with local variable names. |
|
d0c76ce48326
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561 Instead of `:x` or `:xit` you can use `:exit`. |
|
d0c76ce48326
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|
562 Instead of `:t` you can use `:copy`. |
|
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563 |
| 19303 | 564 |
| 565 Comparators ~ | |
| 566 | |
| 567 The 'ignorecase' option is not used for comparators that use strings. | |
|
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|
568 |
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569 |
| 23666 | 570 For loop ~ |
| 571 | |
| 572 Legacy Vim script has some tricks to make a for loop over a list handle | |
| 573 deleting items at the current or previous item. In Vim9 script it just uses | |
| 574 the index, if items are deleted then items in the list will be skipped. | |
| 575 Example legacy script: > | |
| 576 let l = [1, 2, 3, 4] | |
| 577 for i in l | |
| 578 echo i | |
| 579 call remove(l, index(l, i)) | |
| 580 endfor | |
| 581 Would echo: | |
| 582 1 | |
| 583 2 | |
| 584 3 | |
| 585 4 | |
| 586 In compiled Vim9 script you get: | |
| 587 1 | |
| 588 3 | |
| 589 Generally, you should not change the list that is iterated over. Make a copy | |
| 590 first if needed. | |
| 591 | |
| 592 | |
|
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593 White space ~ |
|
94eda51ba9ba
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|
594 |
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595 Vim9 script enforces proper use of white space. This is no longer allowed: > |
|
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596 var name=234 # Error! |
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597 var name= 234 # Error! |
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598 var name =234 # Error! |
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599 There must be white space before and after the "=": > |
|
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600 var name = 234 # OK |
| 21250 | 601 White space must also be put before the # that starts a comment after a |
| 602 command: > | |
|
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603 var name = 234# Error! |
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604 var name = 234 # OK |
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605 |
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606 White space is required around most operators. |
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607 |
| 23466 | 608 White space is required in a sublist (list slice) around the ":", except at |
| 609 the start and end: > | |
| 610 otherlist = mylist[v : count] # v:count has a different meaning | |
| 611 otherlist = mylist[:] # make a copy of the List | |
| 612 otherlist = mylist[v :] | |
| 613 otherlist = mylist[: v] | |
| 614 | |
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615 White space is not allowed: |
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616 - Between a function name and the "(": > |
| 23666 | 617 Func (arg) # Error! |
| 618 Func | |
| 22171 | 619 \ (arg) # Error! |
| 23666 | 620 Func |
| 621 (arg) # Error! | |
| 622 Func(arg) # OK | |
| 623 Func( | |
| 624 arg) # OK | |
| 625 Func( | |
| 626 arg # OK | |
| 627 ) | |
|
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628 |
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629 |
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630 Conditions and expressions ~ |
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631 |
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632 Conditions and expressions are mostly working like they do in other languages. |
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633 Some values are different from legacy Vim script: |
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634 value legacy Vim script Vim9 script ~ |
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635 0 falsy falsy |
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636 1 truthy truthy |
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637 99 truthy Error! |
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638 "0" falsy Error! |
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639 "99" truthy Error! |
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640 "text" falsy Error! |
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641 |
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642 For the "??" operator and when using "!" then there is no error, every value |
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643 is either falsy or truthy. This is mostly like JavaScript, except that an |
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644 empty list and dict is falsy: |
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645 |
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646 type truthy when ~ |
| 23466 | 647 bool true, v:true or 1 |
|
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648 number non-zero |
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649 float non-zero |
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650 string non-empty |
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651 blob non-empty |
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652 list non-empty (different from JavaScript) |
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653 dictionary non-empty (different from JavaScript) |
| 19968 | 654 func when there is a function name |
| 23466 | 655 special true or v:true |
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656 job when not NULL |
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657 channel when not NULL |
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658 class when not NULL |
| 23466 | 659 object when not NULL (TODO: when isTrue() returns true) |
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660 |
|
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661 The boolean operators "||" and "&&" expect the values to be boolean, zero or |
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662 one: > |
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663 1 || false == true |
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664 0 || 1 == true |
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665 0 || false == false |
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666 1 && true == true |
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667 0 && 1 == false |
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668 8 || 0 Error! |
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669 'yes' && 0 Error! |
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670 [] || 99 Error! |
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671 |
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672 When using "!" for inverting, there is no error for using any type and the |
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673 result is a boolean. "!!" can be used to turn any value into boolean: > |
| 23573 | 674 !'yes' == false |
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675 !![] == false |
| 23573 | 676 !![1, 2, 3] == true |
|
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677 |
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678 When using "`.."` for string concatenation arguments of simple types are |
|
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679 always converted to string: > |
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680 'hello ' .. 123 == 'hello 123' |
| 23466 | 681 'hello ' .. v:true == 'hello true' |
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682 |
|
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683 Simple types are string, float, special and bool. For other types |string()| |
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684 can be used. |
|
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685 *false* *true* *null* |
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686 In Vim9 script one can use "true" for v:true, "false" for v:false and "null" |
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687 for v:null. When converting a boolean to a string "false" and "true" are |
|
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688 used, not "v:false" and "v:true" like in legacy script. "v:none" is not |
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689 changed, it is only used in JSON and has no equivalent in other languages. |
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690 |
| 23666 | 691 Indexing a string with [idx] or [idx : idx] uses character indexes instead of |
| 21825 | 692 byte indexes. Example: > |
| 693 echo 'bár'[1] | |
| 694 In legacy script this results in the character 0xc3 (an illegal byte), in Vim9 | |
| 695 script this results in the string 'á'. | |
| 23573 | 696 A negative index is counting from the end, "[-1]" is the last character. |
| 23666 | 697 To exclude the last character use |slice()|. |
| 23573 | 698 If the index is out of range then an empty string results. |
| 699 | |
| 700 In legacy script "++var" and "--var" would be silently accepted and have no | |
| 701 effect. This is an error in Vim9 script. | |
| 702 | |
| 703 Numbers starting with zero are not considered to be octal, only numbers | |
| 704 starting with "0o" are octal: "0o744". |scriptversion-4| | |
| 21825 | 705 |
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706 |
| 21093 | 707 What to watch out for ~ |
| 708 *vim9-gotchas* | |
| 709 Vim9 was designed to be closer to often used programming languages, but at the | |
| 710 same time tries to support the legacy Vim commands. Some compromises had to | |
| 711 be made. Here is a summary of what might be unexpected. | |
| 712 | |
| 713 Ex command ranges need to be prefixed with a colon. > | |
| 23666 | 714 -> legacy Vim: shifts the previous line to the right |
| 715 ->func() Vim9: method call in a continuation line | |
| 716 :-> Vim9: shifts the previous line to the right | |
| 21093 | 717 |
| 23666 | 718 %s/a/b legacy Vim: substitute on all lines |
| 21093 | 719 x = alongname |
| 23666 | 720 % another Vim9: modulo operator in a continuation line |
| 721 :%s/a/b Vim9: substitute on all lines | |
| 722 't legacy Vim: jump to mark t | |
| 723 'text'->func() Vim9: method call | |
| 724 :'t Vim9: jump to mark t | |
| 21093 | 725 |
| 21676 | 726 Some Ex commands can be confused with assignments in Vim9 script: > |
| 23666 | 727 g:name = value # assignment |
| 728 g:pattern:cmd # invalid command - ERROR | |
| 729 :g:pattern:cmd # :global command | |
| 21676 | 730 |
| 21093 | 731 Functions defined with `:def` compile the whole function. Legacy functions |
| 732 can bail out, and the following lines are not parsed: > | |
| 733 func Maybe() | |
| 734 if !has('feature') | |
| 735 return | |
| 736 endif | |
| 737 use-feature | |
| 738 endfunc | |
| 739 Vim9 functions are compiled as a whole: > | |
| 740 def Maybe() | |
| 741 if !has('feature') | |
| 742 return | |
| 743 endif | |
| 23573 | 744 use-feature # May give a compilation error |
| 21093 | 745 enddef |
| 746 For a workaround, split it in two functions: > | |
| 747 func Maybe() | |
| 748 if has('feature') | |
| 23666 | 749 call MaybeInner() |
| 21093 | 750 endif |
| 751 endfunc | |
| 752 if has('feature') | |
| 753 def MaybeInner() | |
| 754 use-feature | |
| 755 enddef | |
| 756 endif | |
| 22171 | 757 Or put the unsupported code inside an `if` with a constant expression that |
| 21991 | 758 evaluates to false: > |
| 759 def Maybe() | |
| 760 if has('feature') | |
| 761 use-feature | |
| 762 endif | |
| 763 enddef | |
| 23573 | 764 < *vim9-user-command* |
| 23666 | 765 Another side effect of compiling a function is that the presence of a user |
| 23573 | 766 command is checked at compile time. If the user command is defined later an |
| 767 error will result. This works: > | |
| 768 command -nargs=1 MyCommand echom <q-args> | |
| 769 def Works() | |
| 770 MyCommand 123 | |
| 771 enddef | |
| 772 This will give an error for "MyCommand" not being defined: > | |
| 773 def Works() | |
| 774 command -nargs=1 MyCommand echom <q-args> | |
| 775 MyCommand 123 | |
| 776 enddef | |
| 777 A workaround is to invoke the command indirectly with `:execute`: > | |
| 778 def Works() | |
| 779 command -nargs=1 MyCommand echom <q-args> | |
| 780 execute 'MyCommand 123' | |
| 781 enddef | |
| 782 | |
| 21991 | 783 Note that for unrecognized commands there is no check for "|" and a following |
| 784 command. This will give an error for missing `endif`: > | |
| 785 def Maybe() | |
| 786 if has('feature') | use-feature | endif | |
| 787 enddef | |
| 21093 | 788 |
| 23305 | 789 Other differences ~ |
| 790 | |
| 791 Patterns are used like 'magic' is set, unless explicitly overruled. | |
| 792 The 'edcompatible' option value is not used. | |
| 793 The 'gdefault' option value is not used. | |
| 794 | |
| 795 | |
|
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796 ============================================================================== |
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797 |
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798 3. New style functions *fast-functions* |
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799 |
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800 THIS IS STILL UNDER DEVELOPMENT - ANYTHING CAN BREAK - ANYTHING CAN CHANGE |
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801 |
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802 *:def* |
| 21825 | 803 :def[!] {name}([arguments])[: {return-type}] |
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804 Define a new function by the name {name}. The body of |
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805 the function follows in the next lines, until the |
|
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806 matching `:enddef`. |
|
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|
807 |
|
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|
808 When {return-type} is omitted or is "void" the |
|
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|
809 function is not expected to return anything. |
|
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|
810 |
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|
811 {arguments} is a sequence of zero or more argument |
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812 declarations. There are three forms: |
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|
813 {name}: {type} |
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814 {name} = {value} |
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|
815 {name}: {type} = {value} |
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|
816 The first form is a mandatory argument, the caller |
|
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|
817 must always provide them. |
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|
818 The second and third form are optional arguments. |
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819 When the caller omits an argument the {value} is used. |
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820 |
| 20856 | 821 The function will be compiled into instructions when |
| 21499 | 822 called, or when `:disassemble` or `:defcompile` is |
| 823 used. Syntax and type errors will be produced at that | |
| 824 time. | |
| 20856 | 825 |
| 21499 | 826 It is possible to nest `:def` inside another `:def` or |
| 827 `:function` up to about 50 levels deep. | |
| 19303 | 828 |
|
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|
829 [!] is used as with `:function`. Note that |
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|
830 script-local functions cannot be deleted or redefined |
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|
831 later in Vim9 script. They can only be removed by |
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|
832 reloading the same script. |
|
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833 |
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|
834 *:enddef* |
| 21499 | 835 :enddef End of a function defined with `:def`. It should be on |
| 836 a line by its own. | |
|
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837 |
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|
838 |
|
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|
839 If the script the function is defined in is Vim9 script, then script-local |
|
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|
840 variables can be accessed without the "s:" prefix. They must be defined |
| 20856 | 841 before the function is compiled. If the script the function is defined in is |
| 842 legacy script, then script-local variables must be accessed with the "s:" | |
| 21991 | 843 prefix and they do not need to exist (they can be deleted any time). |
|
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|
844 |
| 20552 | 845 *:defc* *:defcompile* |
| 846 :defc[ompile] Compile functions defined in the current script that | |
| 847 were not compiled yet. | |
| 848 This will report errors found during the compilation. | |
|
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|
849 |
| 19404 | 850 *:disa* *:disassemble* |
| 851 :disa[ssemble] {func} Show the instructions generated for {func}. | |
| 852 This is for debugging and testing. | |
|
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|
853 Note that for command line completion of {func} you |
|
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|
854 can prepend "s:" to find script-local functions. |
| 19404 | 855 |
| 23737 | 856 :disa[ssemble]! {func} Like `:disassemble` but with the instructions used for |
| 857 profiling. | |
| 858 | |
| 21250 | 859 Limitations ~ |
| 860 | |
| 861 Local variables will not be visible to string evaluation. For example: > | |
|
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|
862 def MapList(): list<string> |
|
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863 var list = ['aa', 'bb', 'cc', 'dd'] |
| 21250 | 864 return range(1, 2)->map('list[v:val]') |
| 865 enddef | |
| 866 | |
| 867 The map argument is a string expression, which is evaluated without the | |
| 868 function scope. Instead, use a lambda: > | |
|
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|
869 def MapList(): list<string> |
|
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870 var list = ['aa', 'bb', 'cc', 'dd'] |
|
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|
871 return range(1, 2)->map(( _, v) => list[v]) |
| 21250 | 872 enddef |
| 873 | |
|
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|
874 The same is true for commands that are not compiled, such as `:global`. |
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|
875 For these the backtick expansion can be used. Example: > |
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|
876 def Replace() |
|
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877 var newText = 'blah' |
|
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|
878 g/pattern/s/^/`=newText`/ |
|
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879 enddef |
| 21250 | 880 |
|
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|
881 ============================================================================== |
|
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|
882 |
|
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|
883 4. Types *vim9-types* |
|
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|
884 |
|
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|
885 THIS IS STILL UNDER DEVELOPMENT - ANYTHING CAN BREAK - ANYTHING CAN CHANGE |
|
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|
886 |
|
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|
887 The following builtin types are supported: |
|
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|
888 bool |
|
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|
889 number |
|
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|
890 float |
|
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|
891 string |
|
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|
892 blob |
|
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|
893 list<{type}> |
|
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|
894 dict<{type}> |
|
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|
895 job |
|
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|
896 channel |
| 19646 | 897 func |
| 19968 | 898 func: {type} |
|
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|
899 func({type}, ...) |
|
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900 func({type}, ...): {type} |
|
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|
901 |
|
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902 Not supported yet: |
|
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|
903 tuple<a: {type}, b: {type}, ...> |
|
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|
904 |
|
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|
905 These types can be used in declarations, but no value will have this type: |
| 21499 | 906 {type}|{type} {not implemented yet} |
|
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|
907 void |
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|
908 any |
|
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|
909 |
|
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|
910 There is no array type, use list<{type}> instead. For a list constant an |
|
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|
911 efficient implementation is used that avoids allocating lot of small pieces of |
|
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|
912 memory. |
|
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|
913 |
|
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|
914 A partial and function can be declared in more or less specific ways: |
|
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|
915 func any kind of function reference, no type |
| 19968 | 916 checking for arguments or return value |
|
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|
917 func: {type} any number and type of arguments with specific |
|
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|
918 return type |
| 19968 | 919 func({type}) function with argument type, does not return |
|
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|
920 a value |
| 19968 | 921 func({type}): {type} function with argument type and return type |
| 922 func(?{type}) function with type of optional argument, does | |
| 923 not return a value | |
| 924 func(...{type}) function with type of variable number of | |
| 925 arguments, does not return a value | |
| 926 func({type}, ?{type}, ...{type}): {type} | |
| 927 function with: | |
| 928 - type of mandatory argument | |
| 929 - type of optional argument | |
| 930 - type of variable number of arguments | |
| 931 - return type | |
|
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|
932 |
|
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|
933 If the return type is "void" the function does not return a value. |
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|
934 |
|
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|
935 The reference can also be a |Partial|, in which case it stores extra arguments |
|
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|
936 and/or a dictionary, which are not visible to the caller. Since they are |
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|
937 called in the same way the declaration is the same. |
|
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|
938 |
|
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939 Custom types can be defined with `:type`: > |
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940 :type MyList list<string> |
|
21715
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|
941 Custom types must start with a capital letter, to avoid name clashes with |
|
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|
942 builtin types added later, similarly to user functions. |
|
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943 {not implemented yet} |
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944 |
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|
945 And classes and interfaces can be used as types: > |
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946 :class MyClass |
|
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947 :var mine: MyClass |
|
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|
948 |
|
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|
949 :interface MyInterface |
|
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|
950 :var mine: MyInterface |
|
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|
951 |
|
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952 :class MyTemplate<Targ> |
|
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953 :var mine: MyTemplate<number> |
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954 :var mine: MyTemplate<string> |
|
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955 |
|
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956 :class MyInterface<Targ> |
|
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957 :var mine: MyInterface<number> |
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958 :var mine: MyInterface<string> |
|
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959 {not implemented yet} |
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960 |
|
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961 |
|
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962 Variable types and type casting ~ |
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963 *variable-types* |
|
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964 Variables declared in Vim9 script or in a `:def` function have a type, either |
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965 specified explicitly or inferred from the initialization. |
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966 |
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967 Global, buffer, window and tab page variables do not have a specific type, the |
|
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968 value can be changed at any time, possibly changing the type. Therefore, in |
|
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969 compiled code the "any" type is assumed. |
|
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970 |
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971 This can be a problem when the "any" type is undesired and the actual type is |
|
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972 expected to always be the same. For example, when declaring a list: > |
|
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973 var l: list<number> = [1, g:two] |
| 23305 | 974 At compile time Vim doesn't know the type of "g:two" and the expression type |
| 975 becomes list<any>. An instruction is generated to check the list type before | |
| 976 doing the assignment, which is a bit inefficient. | |
| 977 *type-casting* | |
| 978 To avoid this, use a type cast: > | |
|
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979 var l: list<number> = [1, <number>g:two] |
| 23305 | 980 The compiled code will then only check that "g:two" is a number and give an |
| 981 error if it isn't. This is called type casting. | |
|
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982 |
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983 The syntax of a type cast is: "<" {type} ">". There cannot be white space |
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984 after the "<" or before the ">" (to avoid them being confused with |
|
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985 smaller-than and bigger-than operators). |
|
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986 |
|
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987 The semantics is that, if needed, a runtime type check is performed. The |
|
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988 value is not actually changed. If you need to change the type, e.g. to change |
|
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989 it to a string, use the |string()| function. Or use |str2nr()| to convert a |
|
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990 string to a number. |
|
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991 |
|
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992 |
|
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993 Type inference ~ |
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994 *type-inference* |
|
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995 In general: Whenever the type is clear it can be omitted. For example, when |
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996 declaring a variable and giving it a value: > |
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997 var name = 0 # infers number type |
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998 var name = 'hello' # infers string type |
|
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999 |
|
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1000 The type of a list and dictionary comes from the common type of the values. |
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1001 If the values all have the same type, that type is used for the list or |
|
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1002 dictionary. If there is a mix of types, the "any" type is used. > |
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1003 [1, 2, 3] list<number> |
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1004 ['a', 'b', 'c'] list<string> |
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1005 [1, 'x', 3] list<any> |
|
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1006 |
| 21991 | 1007 |
|
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1008 Stricter type checking ~ |
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1009 *type-checking* |
| 21991 | 1010 In legacy Vim script, where a number was expected, a string would be |
| 1011 automatically converted to a number. This was convenient for an actual number | |
| 1012 such as "123", but leads to unexpected problems (but no error message) if the | |
| 1013 string doesn't start with a number. Quite often this leads to hard-to-find | |
| 1014 bugs. | |
| 1015 | |
| 1016 In Vim9 script this has been made stricter. In most places it works just as | |
| 22171 | 1017 before, if the value used matches the expected type. There will sometimes be |
| 1018 an error, thus breaking backwards compatibility. For example: | |
| 21991 | 1019 - Using a number other than 0 or 1 where a boolean is expected. *E1023* |
| 1020 - Using a string value when setting a number options. | |
| 1021 - Using a number where a string is expected. *E1024* | |
| 1022 | |
| 23573 | 1023 One consequence is that the item type of a list or dict given to map() must |
| 1024 not change. This will give an error in compiled code: > | |
| 1025 map([1, 2, 3], (i, v) => 'item ' .. i) | |
| 1026 E1012: Type mismatch; expected list<number> but got list<string> | |
| 1027 Instead use |mapnew()|. | |
| 1028 | |
|
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1029 ============================================================================== |
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1030 |
|
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1031 5. Namespace, Import and Export |
|
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1032 *vim9script* *vim9-export* *vim9-import* |
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1033 |
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1034 THIS IS STILL UNDER DEVELOPMENT - ANYTHING CAN BREAK - ANYTHING CAN CHANGE |
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1035 |
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1036 A Vim9 script can be written to be imported. This means that everything in |
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1037 the script is local, unless exported. Those exported items, and only those |
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1038 items, can then be imported in another script. |
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1039 |
| 21991 | 1040 You can cheat by using the global namespace explicitly. We will assume here |
| 1041 that you don't do that. | |
| 1042 | |
|
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1043 |
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1044 Namespace ~ |
|
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1045 *vim9-namespace* |
| 19303 | 1046 To recognize a file that can be imported the `vim9script` statement must |
|
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1047 appear as the first statement in the file. It tells Vim to interpret the |
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1048 script in its own namespace, instead of the global namespace. If a file |
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1049 starts with: > |
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1050 vim9script |
|
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1051 var myvar = 'yes' |
|
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1052 Then "myvar" will only exist in this file. While without `vim9script` it would |
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1053 be available as `g:myvar` from any other script and function. |
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1054 |
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1055 The variables at the file level are very much like the script-local "s:" |
| 20115 | 1056 variables in legacy Vim script, but the "s:" is omitted. And they cannot be |
| 1057 deleted. | |
|
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1058 |
| 20115 | 1059 In Vim9 script the global "g:" namespace can still be used as before. And the |
| 1060 "w:", "b:" and "t:" namespaces. These have in common that variables are not | |
| 1061 declared and they can be deleted. | |
|
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1062 |
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1063 A side effect of `:vim9script` is that the 'cpoptions' option is set to the |
|
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1064 Vim default value, like with: > |
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1065 :set cpo&vim |
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1066 One of the effects is that |line-continuation| is always enabled. |
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1067 The original value of 'cpoptions' is restored at the end of the script. |
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1068 |
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1069 |
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1070 Export ~ |
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1071 *:export* *:exp* |
| 21499 | 1072 Exporting an item can be written as: > |
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1073 export const EXPORTED_CONST = 1234 |
|
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1074 export var someValue = ... |
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1075 export final someValue = ... |
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1076 export const someValue = ... |
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1077 export def MyFunc() ... |
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1078 export class MyClass ... |
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1079 |
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1080 As this suggests, only constants, variables, `:def` functions and classes can |
| 21499 | 1081 be exported. {classes are not implemented yet} |
|
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1082 |
| 20856 | 1083 *E1042* |
| 1084 `:export` can only be used in Vim9 script, at the script level. | |
|
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1085 |
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1086 |
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1087 Import ~ |
| 20965 | 1088 *:import* *:imp* *E1094* |
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1089 The exported items can be imported individually in another Vim9 script: > |
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1090 import EXPORTED_CONST from "thatscript.vim" |
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1091 import MyClass from "myclass.vim" |
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1092 |
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1093 To import multiple items at the same time: > |
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1094 import {someValue, MyClass} from "thatscript.vim" |
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1095 |
| 19303 | 1096 In case the name is ambiguous, another name can be specified: > |
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1097 import MyClass as ThatClass from "myclass.vim" |
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1098 import {someValue, MyClass as ThatClass} from "myclass.vim" |
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1099 |
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1100 To import all exported items under a specific identifier: > |
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1101 import * as That from 'thatscript.vim' |
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1102 |
| 22328 | 1103 {not implemented yet: using "This as That"} |
| 1104 | |
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1105 Then you can use "That.EXPORTED_CONST", "That.someValue", etc. You are free |
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1106 to choose the name "That", but it is highly recommended to use the name of the |
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1107 script file to avoid confusion. |
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1108 |
| 22171 | 1109 `:import` can also be used in legacy Vim script. The imported items still |
| 1110 become script-local, even when the "s:" prefix is not given. | |
| 1111 | |
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1112 The script name after `import` can be: |
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1113 - A relative path, starting "." or "..". This finds a file relative to the |
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1114 location of the script file itself. This is useful to split up a large |
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1115 plugin into several files. |
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1116 - An absolute path, starting with "/" on Unix or "D:/" on MS-Windows. This |
| 22723 | 1117 will rarely be used. |
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1118 - A path not being relative or absolute. This will be found in the |
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1119 "import" subdirectories of 'runtimepath' entries. The name will usually be |
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1120 longer and unique, to avoid loading the wrong file. |
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1121 |
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1122 Once a vim9 script file has been imported, the result is cached and used the |
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1123 next time the same script is imported. It will not be read again. |
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1124 *:import-cycle* |
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1125 The `import` commands are executed when encountered. If that script (directly |
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1126 or indirectly) imports the current script, then items defined after the |
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1127 `import` won't be processed yet. Therefore cyclic imports can exist, but may |
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1128 result in undefined items. |
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1129 |
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1130 |
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1131 Import in an autoload script ~ |
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1132 |
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1133 For optimal startup speed, loading scripts should be postponed until they are |
| 19303 | 1134 actually needed. A recommended mechanism: |
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1135 |
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1136 1. In the plugin define user commands, functions and/or mappings that refer to |
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1137 an autoload script. > |
| 23666 | 1138 command -nargs=1 SearchForStuff searchfor#Stuff(<f-args>) |
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1139 |
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1140 < This goes in .../plugin/anyname.vim. "anyname.vim" can be freely chosen. |
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1141 |
| 21825 | 1142 2. In the autoload script do the actual work. You can import items from |
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1143 other files to split up functionality in appropriate pieces. > |
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1144 vim9script |
| 23573 | 1145 import FilterFunc from "../import/someother.vim" |
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1146 def searchfor#Stuff(arg: string) |
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1147 var filtered = FilterFunc(arg) |
|
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1148 ... |
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1149 < This goes in .../autoload/searchfor.vim. "searchfor" in the file name |
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1150 must be exactly the same as the prefix for the function name, that is how |
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1151 Vim finds the file. |
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1152 |
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1153 3. Other functionality, possibly shared between plugins, contains the exported |
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1154 items and any private items. > |
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1155 vim9script |
|
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1156 var localVar = 'local' |
| 22171 | 1157 export def FilterFunc(arg: string): string |
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1158 ... |
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1159 < This goes in .../import/someother.vim. |
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1160 |
|
21771
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1161 When compiling a `:def` function and a function in an autoload script is |
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1162 encountered, the script is not loaded until the `:def` function is called. |
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1163 |
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1164 |
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1165 Import in legacy Vim script ~ |
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1166 |
| 20856 | 1167 If an `import` statement is used in legacy Vim script, the script-local "s:" |
| 1168 namespace will be used for the imported item, even when "s:" is not specified. | |
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1169 |
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1170 |
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1171 ============================================================================== |
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1172 |
| 22328 | 1173 6. Future work: classes *vim9-classes* |
| 1174 | |
| 1175 Above "class" was mentioned a few times, but it has not been implemented yet. | |
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1176 Most of Vim9 script can be created without this functionality, and since |
| 22328 | 1177 implementing classes is going to be a lot of work, it is left for the future. |
| 1178 For now we'll just make sure classes can be added later. | |
| 1179 | |
| 1180 Thoughts: | |
| 1181 - `class` / `endclass`, everything in one file | |
| 1182 - Class names are always CamelCase | |
| 1183 - Single constructor | |
| 1184 - Single inheritance with `class ThisClass extends BaseClass` | |
| 1185 - `abstract class` | |
| 1186 - `interface` (Abstract class without any implementation) | |
| 1187 - `class SomeClass implements SomeInterface` | |
| 1188 - Generics for class: `class <Tkey, Tentry>` | |
| 1189 - Generics for function: `def <Tkey> GetLast(key: Tkey)` | |
| 1190 | |
| 1191 Again, much of this is from TypeScript. | |
| 1192 | |
| 1193 Some things that look like good additions: | |
| 1194 - Use a class as an interface (like Dart) | |
| 1195 - Extend a class with methods, using an import (like Dart) | |
| 1196 | |
| 1197 An important class that will be provided is "Promise". Since Vim is single | |
| 1198 threaded, connecting asynchronous operations is a natural way of allowing | |
| 1199 plugins to do their work without blocking the user. It's a uniform way to | |
| 1200 invoke callbacks and handle timeouts and errors. | |
| 1201 | |
| 1202 ============================================================================== | |
| 1203 | |
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1204 9. Rationale *vim9-rationale* |
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1205 |
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1206 The :def command ~ |
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1207 |
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1208 Plugin writers have asked for much faster Vim script. Investigations have |
| 19303 | 1209 shown that keeping the existing semantics of function calls make this close to |
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1210 impossible, because of the overhead involved with calling a function, setting |
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1211 up the local function scope and executing lines. There are many details that |
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1212 need to be handled, such as error messages and exceptions. The need to create |
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1213 a dictionary for a: and l: scopes, the a:000 list and several others add too |
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1214 much overhead that cannot be avoided. |
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1215 |
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1216 Therefore the `:def` method to define a new-style function had to be added, |
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1217 which allows for a function with different semantics. Most things still work |
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1218 as before, but some parts do not. A new way to define a function was |
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1219 considered the best way to separate the legacy style code from Vim9 style code. |
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1220 |
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1221 Using "def" to define a function comes from Python. Other languages use |
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1222 "function" which clashes with legacy Vim script. |
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1223 |
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1224 |
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1225 Type checking ~ |
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1226 |
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1227 When compiling lines of Vim commands into instructions as much as possible |
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1228 should be done at compile time. Postponing it to runtime makes the execution |
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1229 slower and means mistakes are found only later. For example, when |
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1230 encountering the "+" character and compiling this into a generic add |
| 23666 | 1231 instruction, at runtime the instruction would have to inspect the type of the |
| 1232 arguments and decide what kind of addition to do. And when the type is | |
| 1233 dictionary throw an error. If the types are known to be numbers then an "add | |
| 1234 number" instruction can be used, which is faster. The error can be given at | |
| 1235 compile time, no error handling is needed at runtime, since adding two numbers | |
| 1236 cannot fail. | |
|
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1237 |
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1238 The syntax for types, using <type> for compound types, is similar to Java. It |
|
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1239 is easy to understand and widely used. The type names are what were used in |
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1240 Vim before, with some additions such as "void" and "bool". |
|
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1241 |
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1242 |
| 22328 | 1243 Removing clutter and weirdness ~ |
| 20856 | 1244 |
| 22328 | 1245 Once decided that `:def` functions have different syntax than legacy functions, |
| 1246 we are free to add improvements to make the code more familiar for users who | |
| 1247 know popular programming languages. In other words: remove weird things that | |
|
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1248 only Vim does. |
| 22328 | 1249 |
| 1250 We can also remove clutter, mainly things that were done to make Vim script | |
|
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1251 backwards compatible with the good old Vi commands. |
| 20856 | 1252 |
| 22328 | 1253 Examples: |
| 1254 - Drop `:call` for calling a function and `:eval` for manipulating data. | |
| 1255 - Drop using a leading backslash for line continuation, automatically figure | |
| 1256 out where an expression ends. | |
| 20856 | 1257 |
| 22328 | 1258 However, this does require that some things need to change: |
| 1259 - Comments start with # instead of ", to avoid confusing them with strings. | |
|
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1260 This is good anyway, it is known from several popular languages. |
| 22328 | 1261 - Ex command ranges need to be prefixed with a colon, to avoid confusion with |
| 1262 expressions (single quote can be a string or a mark, "/" can be divide or a | |
| 1263 search command, etc.). | |
| 1264 | |
| 1265 Goal is to limit the differences. A good criteria is that when the old syntax | |
|
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1266 is accidentally used you are very likely to get an error message. |
| 20856 | 1267 |
| 1268 | |
|
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1269 Syntax and semantics from popular languages ~ |
|
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1270 |
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1271 Script writers have complained that the Vim script syntax is unexpectedly |
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1272 different from what they are used to. To reduce this complaint popular |
| 20856 | 1273 languages are used as an example. At the same time, we do not want to abandon |
| 1274 the well-known parts of legacy Vim script. | |
|
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1275 |
|
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1276 For many things TypeScript is followed. It's a recent language that is |
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1277 gaining popularity and has similarities with Vim script. It also has a |
| 22328 | 1278 mix of static typing (a variable always has a known value type) and dynamic |
|
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1279 typing (a variable can have different types, this changes at runtime). Since |
| 22328 | 1280 legacy Vim script is dynamically typed and a lot of existing functionality |
| 1281 (esp. builtin functions) depends on that, while static typing allows for much | |
| 1282 faster execution, we need to have this mix in Vim9 script. | |
| 1283 | |
| 22171 | 1284 There is no intention to completely match TypeScript syntax and semantics. We |
| 1285 just want to take those parts that we can use for Vim and we expect Vim users | |
| 22328 | 1286 will be happy with. TypeScript is a complex language with its own history, |
| 1287 advantages and disadvantages. To get an idea of the disadvantages read the | |
| 1288 book: "JavaScript: The Good Parts". Or find the article "TypeScript: the good | |
|
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1289 parts" and read the "Things to avoid" section. |
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1290 |
| 22328 | 1291 People familiar with other languages (Java, Python, etc.) will also find |
| 1292 things in TypeScript that they do not like or do not understand. We'll try to | |
| 1293 avoid those things. | |
|
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1294 |
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1295 Specific items from TypeScript we avoid: |
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1296 - Overloading "+", using it both for addition and string concatenation. This |
|
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1297 goes against legacy Vim script and often leads to mistakes. For that reason |
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1298 we will keep using ".." for string concatenation. Lua also uses ".." this |
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1299 way. And it allows for conversion to string for more values. |
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1300 - TypeScript can use an expression like "99 || 'yes'" in a condition, but |
|
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1301 cannot assign the value to a boolean. That is inconsistent and can be |
|
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1302 annoying. Vim recognizes an expression with && or || and allows using the |
|
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1303 result as a bool. TODO: to be reconsidered |
|
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1304 - TypeScript considers an empty string as Falsy, but an empty list or dict as |
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1305 Truthy. That is inconsistent. In Vim an empty list and dict are also |
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1306 Falsy. |
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1307 - TypeScript has various "Readonly" types, which have limited usefulness, |
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1308 since a type cast can remove the immutable nature. Vim locks the value, |
|
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1309 which is more flexible, but is only checked at runtime. |
| 22171 | 1310 |
|
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1311 |
|
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1312 Declarations ~ |
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1313 |
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1314 Legacy Vim script uses `:let` for every assignment, while in Vim9 declarations |
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1315 are used. That is different, thus it's good to use a different command: |
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1316 `:var`. This is used in many languages. The semantics might be slightly |
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1317 different, but it's easily recognized as a declaration. |
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1318 |
| 23047 | 1319 Using `:const` for constants is common, but the semantics varies. Some |
|
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1320 languages only make the variable immutable, others also make the value |
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1321 immutable. Since "final" is well known from Java for only making the variable |
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1322 immutable we decided to use that. And then `:const` can be used for making |
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1323 both immutable. This was also used in legacy Vim script and the meaning is |
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1324 almost the same. |
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1325 |
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1326 What we end up with is very similar to Dart: > |
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1327 :var name # mutable variable and value |
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1328 :final name # immutable variable, mutable value |
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1329 :const name # immutable variable and value |
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1330 |
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1331 Since legacy and Vim9 script will be mixed and global variables will be |
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1332 shared, optional type checking is desirable. Also, type inference will avoid |
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1333 the need for specifying the type in many cases. The TypeScript syntax fits |
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1334 best for adding types to declarations: > |
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1335 var name: string # string type is specified |
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1336 ... |
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1337 name = 'John' |
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1338 const greeting = 'hello' # string type is inferred |
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1339 |
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1340 This is how we put types in a declaration: > |
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1341 var mylist: list<string> |
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1342 final mylist: list<string> = ['foo'] |
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1343 def Func(arg1: number, arg2: string): bool |
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1344 |
|
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1345 Two alternatives were considered: |
|
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1346 1. Put the type before the name, like Dart: > |
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1347 var list<string> mylist |
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1348 final list<string> mylist = ['foo'] |
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1349 def Func(number arg1, string arg2) bool |
|
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1350 2. Put the type after the variable name, but do not use a colon, like Go: > |
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1351 var mylist list<string> |
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1352 final mylist list<string> = ['foo'] |
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1353 def Func(arg1 number, arg2 string) bool |
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1354 |
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1355 The first is more familiar for anyone used to C or Java. The second one |
| 22565 | 1356 doesn't really have an advantage over the first, so let's discard the second. |
|
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1357 |
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1358 Since we use type inference the type can be left out when it can be inferred |
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1359 from the value. This means that after `var` we don't know if a type or a name |
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1360 follows. That makes parsing harder, not only for Vim but also for humans. |
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1361 Also, it will not be allowed to use a variable name that could be a type name, |
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1362 using `var string string` is too confusing. |
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1363 |
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1364 The chosen syntax, using a colon to separate the name from the type, adds |
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1365 punctuation, but it actually makes it easier to recognize the parts of a |
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1366 declaration. |
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1367 |
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1368 |
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1369 Expressions ~ |
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1370 |
| 22565 | 1371 Expression evaluation was already close to what other languages are doing. |
| 1372 Some details are unexpected and can be improved. For example a boolean | |
| 1373 condition would accept a string, convert it to a number and check if the | |
| 1374 number is non-zero. This is unexpected and often leads to mistakes, since | |
| 1375 text not starting with a number would be converted to zero, which is | |
| 22723 | 1376 considered false. Thus using a string for a condition would often not give an |
| 1377 error and be considered false. That is confusing. | |
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1378 |
| 23047 | 1379 In Vim9 type checking is stricter to avoid mistakes. Where a condition is |
| 22565 | 1380 used, e.g. with the `:if` command and the `||` operator, only boolean-like |
| 1381 values are accepted: | |
| 1382 true: `true`, `v:true`, `1`, `0 < 9` | |
| 1383 false: `false`, `v:false`, `0`, `0 > 9` | |
| 1384 Note that the number zero is false and the number one is true. This is more | |
| 22723 | 1385 permissive than most other languages. It was done because many builtin |
| 22565 | 1386 functions return these values. |
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1387 |
| 22565 | 1388 If you have any type of value and want to use it as a boolean, use the `!!` |
| 1389 operator: | |
| 1390 true: !`!'text'`, `!![99]`, `!!{'x': 1}`, `!!99` | |
| 1391 false: `!!''`, `!![]`, `!!{}` | |
| 1392 | |
| 1393 From a language like JavaScript we have this handy construct: > | |
| 1394 GetName() || 'unknown' | |
| 1395 However, this conflicts with only allowing a boolean for a condition. | |
| 1396 Therefore the "??" operator was added: > | |
| 1397 GetName() ?? 'unknown' | |
| 1398 Here you can explicitly express your intention to use the value as-is and not | |
| 1399 result in a boolean. This is called the |falsy-operator|. | |
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1400 |
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1401 |
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1402 Import and Export ~ |
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1403 |
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1404 A problem of legacy Vim script is that by default all functions and variables |
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1405 are global. It is possible to make them script-local, but then they are not |
| 22171 | 1406 available in other scripts. This defies the concept of a package that only |
| 1407 exports selected items and keeps the rest local. | |
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1408 |
| 21825 | 1409 In Vim9 script a mechanism very similar to the JavaScript import and export |
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1410 mechanism is supported. It is a variant to the existing `:source` command |
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1411 that works like one would expect: |
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1412 - Instead of making everything global by default, everything is script-local, |
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1413 unless exported. |
| 22171 | 1414 - When importing a script the symbols that are imported are explicitly listed, |
| 1415 avoiding name conflicts and failures if functionality is added later. | |
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1416 - The mechanism allows for writing a big, long script with a very clear API: |
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1417 the exported function(s) and class(es). |
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1418 - By using relative paths loading can be much faster for an import inside of a |
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1419 package, no need to search many directories. |
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1420 - Once an import has been used, it can be cached and loading it again can be |
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1421 avoided. |
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1422 - The Vim-specific use of "s:" to make things script-local can be dropped. |
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1423 |
| 20856 | 1424 When sourcing a Vim9 script from a legacy script, only the items defined |
| 1425 globally can be used, not the exported items. Alternatives considered: | |
| 1426 - All the exported items become available as script-local items. This makes | |
| 22171 | 1427 it uncontrollable what items get defined and likely soon leads to trouble. |
| 20856 | 1428 - Use the exported items and make them global. Disadvantage is that it's then |
| 1429 not possible to avoid name clashes in the global namespace. | |
| 1430 - Completely disallow sourcing a Vim9 script, require using `:import`. That | |
| 1431 makes it difficult to use scripts for testing, or sourcing them from the | |
| 1432 command line to try them out. | |
| 22171 | 1433 Note that you can also use `:import` in legacy Vim script, see above. |
| 20856 | 1434 |
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1435 |
| 22328 | 1436 Compiling functions early ~ |
| 1437 | |
| 1438 Functions are compiled when called or when `:defcompile` is used. Why not | |
| 1439 compile them early, so that syntax and type errors are reported early? | |
| 1440 | |
| 1441 The functions can't be compiled right away when encountered, because there may | |
| 1442 be forward references to functions defined later. Consider defining functions | |
| 1443 A, B and C, where A calls B, B calls C, and C calls A again. It's impossible | |
| 1444 to reorder the functions to avoid forward references. | |
| 1445 | |
| 1446 An alternative would be to first scan through the file to locate items and | |
| 1447 figure out their type, so that forward references are found, and only then | |
| 1448 execute the script and compile the functions. This means the script has to be | |
| 1449 parsed twice, which is slower, and some conditions at the script level, such | |
| 1450 as checking if a feature is supported, are hard to use. An attempt was made | |
| 1451 to see if it works, but it turned out to be impossible to make work nicely. | |
| 1452 | |
| 1453 It would be possible to compile all the functions at the end of the script. | |
| 1454 The drawback is that if a function never gets called, the overhead of | |
| 1455 compiling it counts anyway. Since startup speed is very important, in most | |
| 1456 cases it's better to do it later and accept that syntax and type errors are | |
| 1457 only reported then. In case these errors should be found early, e.g. when | |
| 1458 testing, the `:defcompile` command will help out. | |
| 1459 | |
| 1460 | |
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1461 Why not use an embedded language? ~ |
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1462 |
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1463 Vim supports interfaces to Perl, Python, Lua, Tcl and a few others. But |
| 22328 | 1464 these interfaces have never become widely used, for various reasons. When |
| 1465 Vim9 was designed a decision was made to make these interfaces lower priority | |
| 1466 and concentrate on Vim script. | |
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1467 |
| 22328 | 1468 Still, plugin writers may find other languages more familiar, want to use |
| 1469 existing libraries or see a performance benefit. We encourage plugin authors | |
| 1470 to write code in any language and run it as an external tool, using jobs and | |
| 1471 channels. We can try to make this easier somehow. | |
| 1472 | |
| 1473 Using an external tool also has disadvantages. An alternative is to convert | |
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1474 the tool into Vim script. For that to be possible without too much |
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1475 translation, and keeping the code fast at the same time, the constructs of the |
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1476 tool need to be supported. Since most languages support classes the lack of |
| 22171 | 1477 support for classes in Vim is then a problem. |
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1478 |
| 22328 | 1479 |
| 1480 Classes ~ | |
| 1481 | |
| 1482 Vim supports a kind-of object oriented programming by adding methods to a | |
| 1483 dictionary. With some care this can be made to work, but it does not look | |
| 1484 like real classes. On top of that, it's quite slow, because of the use of | |
| 1485 dictionaries. | |
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1486 |
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1487 The support of classes in Vim9 script is a "minimal common functionality" of |
| 22171 | 1488 class support in most languages. It works much like Java, which is the most |
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1489 popular programming language. |
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1490 |
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1491 |
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1492 |
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1493 vim:tw=78:ts=8:noet:ft=help:norl: |