Wednesday, July 7, 2021

Re: Help converting function to Vim9 script

> Any idea what would be the best way to convert the snippet above?

Move the `i` variable in the script-local namespace.  That is, don't declare it inside the function, but at the script-level.  You can still reset it to a default value whenever the function is invoked:

    vim9script
    var i: number
    def FixBeginfig()
        i = 1
        global /^beginfig(\d*);$/ substitute//\='beginfig(' .. i .. ');'/ | ++i
    enddef
    command -buffer -nargs=0 -bar FixBeginfigs FixBeginfig()

This works because – in a Vim9 script – all commands are executed in the Vim9 script context.  As a result, they have access to any Vim9 syntax, and to all items defined in the script-local namespace.

Whether they're executed from a global command, an autocmd, a user command, a simple `:execute`, ... it doesn't matter.

For this reason, in your user command definition, you don't need `:call` nor `<sid>`.  You don't need a bang after `:command` either since the patch v8.1.0573.

---

However, as mentioned earlier, there won't be a speed increase because the command is not compiled, just executed.  Like most (all?) commands executed by another command.  This is confirmed by the output of `:disassemble`:

    <SNR>1_FixBeginfig
        i = 1
       0 PUSHNR 1
       1 STORESCRIPT i-0 in /tmp/t.vim

        global /^beginfig(\d*);$/ substitute//\='beginfig(' .. i .. ');'/ | ++i
       2 EXEC     global /^beginfig(\d*);$/ substitute//\='beginfig(' .. i .. ');'/ | ++i
       3 RETURN void

Notice that the second generated instruction is a simple `EXEC`.

FWIW, I would still refactor the code in Vim9.  Mainly because of type checking, and for better readability.



On Sunday, July 4, 2021 at 8:42:10 PM UTC+2 Lifepillar wrote:
The MetaPost plugin in Vim contains the following definition to replace
the n-th occurrence of `beginfig(...)` with `beginfig(n)`:

function! s:fix_beginfigs()
let i = 1
g/^beginfig(\d*);$/s//\='beginfig('.i.');'/ | let i = i + 1
endfunction

command -nargs=0 FixBeginfigs call s:fix_beginfigs()

On attempting to convert it to Vim9 script, I came up with this:

def FixBeginfig()
i = 1
g/^beginfig(\d*);$/s//\='beginfig(' .. i .. ');'/ | i += 1
enddef

command! -buffer -nargs=0 -bar FixBeginfigs call <sid>FixBeginfig()

But this results in 'Undefined variable: i', likely because the command
is not evaluated in Vim9 script context.

Any idea what would be the best way to convert the snippet above?

Thanks,
Life.


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