Mark variable as local without defining it as local

[Real-Gecko]

I have a bunch of files that declare a variable without marking it as local

NewShipType = StartShipConfig()

Problem is that each of this files is executed in it's own context by the game, so NewShipType is not global, but LuaLS thinks it is. So Go to definition on some property of NewShipType shows list of all assignments of this property from all files instead of going to declaration of the field from class. Is there a way to mark variable as local without explicitly marking it as local?

local NewShipType = StartShipConfig()

Maybe something like

---@local
NewShipType = StartShipConfig()

[tomlau10]

Problem is that each of this files is executed in it's own context by the game

When LuaLS works in workspace mode, all files in the same workspace are treated as if they are in the same single Lua runtime.
Therefore the "global" variable defined in any of these files will be treated as globals for all files.
And currently LuaLS doesn't support setfenv to set the function/code chunk environment 😕

As for supporting per-file environment, there are already many feature request:

• Feature request: Per-firectory or per-file environments #3185
• How to apply different libraries to different files? #2157
• Global in one file affects diagnostics in another #2340
• [Feature Request] Multiple-project/Monorepo support #2962
• How to "scope" definition file? #3030

But I guess under the current architecture / working mechanism of LuaLS, it is very difficult to implement ☹️
Maybe it will have better support for this in the v4.0 rewrite.

---

May I ask why don't you just write local NewShipType there, if you can accept a solution of adding @local ? 🤔
Is it because NewShipType actually needs to be a global variable, but only visible in it's own context ?

I don't know much about LuaLS's plugin system, but seems it can transform the file buffer internally when the file is being processed inside LuaLS.
Maybe you can write a custom plugin, which will only active for some specific paths in your project, and it will add local to these variable internally when the file buffer is processed by LuaLS 🤔 🤔

[tomlau10]

I just tested around, and the following simple plugin implements a ---@local feature

• search the text buffer for any ---@local\n
• then strip out the ---@ part, such that this token becomes just a local
• which will then make the next token in the buffer as a local variable when interpreted by LuaLS

=> you can now see that variable A is interpreted as local by LuaLS 👀

you may use the following as the baseline when you develop you plugin 😄

• plugin.lua

function OnSetText(uri, text)
    -- print(uri, text)
    if not uri:match("main%.lua$") then
        return
    end

    -- for each `---@local`, remove the `---@`
    -- such that it becomes a `local` keyword for next line
    local diffs = {}
    for start, finish in text:gmatch '()---@()local\n' do
        -- print(start, finish)
        diffs[#diffs+1] = {
            start  = start,
            finish = finish-1,
            text   = "",
        }
    end
    return diffs
end

• .luarc.json add a line "runtime.plugin": "plugin.lua"
• ref: https://luals.github.io/wiki/plugins/

[Real-Gecko]

I've tried your plugin ant it worked, now I'm curious if I can add local automatically, without modifying initial code using this method. I've tried following:

local util = require 'utility'

function OnSetText(uri, text)
    print('on set text call')
    print(uri, text)
    if not uri:match("main%.lua$") then
        return
    end

    local diffs = {
        [1] = {
            start = 1,
            finsih = 6,
            text = "local "
        }
    }
    print('diffs are')
    print(util.dump(diffs))
    return diffs
end

But I get following error script/string-merger.lua:71: attempt to perform arithmetic on a nil value (field 'finish'), so I guess I'm doing something wrong, any clues?

[Real-Gecko]

Lol I had a typo finsih = 6, finsih instead of finish, anyway looks like this won't help as I've discovered an interesting issue. Go To Definition does not work even if local is explicitly set. I've filed the issue #3222

[tomlau10]

(I haven't read your #3222 yet)

IIUC, in your test plugin you want to add "local " at the beginning of the file, without replacing any text in the buffer.
In this case, I think you have to use start = 1, finish = 0 🤔
Otherwise, it means to replace the text buffer 1..6 with "local "

• For example, given the following text buffer

A = 1
print(A)

if you use start = 1, finish = 6
=> the diffed.lua will show the following

local print(A)

which means the bytes from 1..6: A = 1\n get replaced by local

• when using start = 1, finish = 0
  => the diffed.lua will correctly show

local A = 1
print(A)

=> the local just get inserted at the beginning, without replacing any text in the buffer

[Real-Gecko]

IIUC, in your test plugin you want to add "local " at the beginning of the file, without replacing any text in the buffer.

Thanks for the info!