LuaLS / LuaLS/lua-language-server
No way to annotate the parameters on function types
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Description
By "function type" I'm referring to the fun(param:type):return syntax, when used in a @type, @param, or @overload annotation. What I would like to do is to give a description for each parameter in the function type, but there doesn't seem to be any syntax that supports this. The @param annotation only applies to a literal code function, and I can't split the function type across multiple lines like I can with an enum definition.
Here are some examples of what I mean.
- Since the LuaDoc does not understand metafunctions, I've used
---@type fun...in a number of places to annotate objects that have a__callmetafunction.
---@type fun(x:integer, y:integer)
---@param x integer The x coordinate of the map <-- This does nothing
---@param y integer The y coordinate of the map <-- This does nothing
map = setmetatable({}, {
__call = function(self, x, y)
return self[x + y * self.width]
end
})
map.width = 0
map.height = 0
When hovering over map, I would like to see a tooltip similar to the following:
global map: fun(x: integer, y: integer) {
height: integer = 0,
width: integer = 0,
}
@param x — The x coordinate of the map
@param y — The y coordinate of the map
- Sometimes, I want to declare that a class has a function on it, without explicitly defining that function. This could be a class method, but more often it's a callback – the intent is for someone to assign a function with the required signature to that key.
---@class text_field
---@param value string The new value of the field <-- This does nothing
---@field onmodify fun(value:string)
---@return text_field
function make_text_field() end
-- Client code:
local f = make_text_field()
function f.onmodify(val) end
local new_val
f.onmodify(new_val)
When hovering over f.onmodify, I would like to see a tooltip similar to the following:
function f.onmodify(val:string)
@param val — The new value of the field
- Sometimes a function needs to take a callback function as a parameter. In this case, I want to describe the parameters to that passed in function.
---@param list string
---@param value string The current value <-- This does nothing
---@param fcn fun(value:string)
function foreach(list, fcn) end
-- Client code:
foreach({'a','b','c'}, function(s) end)
When hovering over callback, I would like to see a tooltip similar to the following:
function (s:string)
@param s — The current value
- Sometimes a function needs to return a function, and I would like to describe the parameters the new function takes.
---@param expression string
---@param params table Params to pass to the formula <-- This does nothing
---@return fun(params:table):number
function parse(expression) end
-- Client code:
local formula = parse "a + 2"
formula{a = 5}
When hovering over formula, I would like to see a tooltip similar to the following:
function formula(params:table):number
@param params — Params to pass to the formula
- When specifying alternate parameter lists with
@overload, I'd like to be able to give a description of the other parameters.
---@alias location {x:integer, y:integer}
---@param x integer X coordinate
---@param y integer Y coordinate
---@param loc location X and Y coordinate <-- This is a warning
---@overload fun(loc:location)
function draw(x, y) end
When hovering over draw, I would like to see a tooltip similar to the following:
(2 definitions, 2 prototypes)
(1) function draw(loc: location)
(1) function draw(x: integer, y: integer)
@param x — X coordinate
@param y — Y coordinate
@param loc — X and Y coordinate
In this last case, the tooltip actually looks almost like the above, although the final line is formatted like a header for some reason. However, there's also an "undefined param loc" warning."
Contributor guide
First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
Research direction
Start by reviewing the existing LuaDoc handling for function types, @param, and @overload annotations, then compare the hover output in the five examples. Done means a supported annotation syntax can describe parameters inside function types and those descriptions appear in relevant hovers without spurious undefined-parameter warnings.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- lua
- Domain
- developer-experience, tooling
- Issue type
- Feature
- Difficulty
- 5/5
- Estimated time
- Over a week
- Activity status
- Stale
- Clarity
- Mostly clear
- Newbie friendliness
- 35/100