Is it possible in an array to get the array index?

[RobertSobral]

I'm testing with lua code, to obtain array using metatable

but when I define my array, it does not return the index

for example:

local function CreateMtbl(tbl)
    return {
        __index = function(t, k)
            return tbl.index[k](t.ptr)
        end,
        __newindex = function(t, k, v)
            return tbl.newindex[k](t.ptr, v)
        end,
        __tostring = function(t)
            return t.ptr
        end
    }
end

local function CallFunc(ptr, pointer, func)
    local function idx(t, i)
        return func(pointer(t.ptr, i))
    end
    local function tostring(t)
        return t.ptr
    end

    return setmetatable({ptr = ptr}, {__index = idx, __tostring = tostring})
end


--- @class var_cast
--- @field id integer
--- @field name integer
--- @field timeout integer
--- @return var_cast
local var_cast = {
        id = func.get_id,
        name = func.get_name,
        timeout = func.get_timeout
}
function MyVarCast(ptr)
    return setmetatable({ptr = ptr}, CreateMetable(my_class))
end


local my_class = {
    var4 = function (ptr) return CallFunc(ptr, func.get_var4, var_cast) end
}

--- @class my_class
--- @field var4 var_cast[]
--- @return my_class
function MyClass(ptr)
    return setmetatable({ptr = ptr}, CreateMtbl(my_class))
end

When I do

local myid = MyClass(myptr).var4[1].id

he returns me (field) var_cast.id: integer

What can I do to get it to return the index for example:

for i = 0, 10 do
    local m_id = myid.my_class[i].id
end

expected return

(field) var_cast.i.id: integer

local m_id = myid.my_class[1].id

expected return

(field) var_cast.1.id: integer

[tomlau10]

I don't think this is ever possible. 😕

In LuaLS there is no dynamically created classes, all classes must be defined by @class first.
In your case, the only class defined is var_cast, which has an id field.

• objects from the same class have same fields
• luals annotation is used to define the class, not an identifier to an object instance

---

local myid = MyClass(myptr).var4[1].id

• var4 is of type var_cast[]
• so any positive integer index to it will return a var_cast type
  • the type of var4[1] == var4[2] == var4[i] == var_cast
• there is no such var_cast.i or var_cast.1 type
  the id field belongs to var_cast type

[RobertSobral]

Is there something that symbolizes then (field) 1.id and (field) i.id ?

[tomlau10]

I don't quite understand the question here. 😕

I can see what you want to achieve from your given examples above, but I don't think they are conceptually correct.
AFAIK, LuaLS aims to provide type inferences on variables and table fields.
By table fields it means fields which belong to a table/class, or in general a type container.

• In your examples, the field id belongs to the type var_cast => that's why it is showing (field) var_cast.id
• Conceptually there is no var_cast.1 / var_cast.i type which contains a id field.
  This concept seems totally wrong to me 😕😕

---

Let's consider the following example, a hash table of id: integer => Object

---@class Object
---@field id integer

---@type table<integer, Object>
local objects = {}

local o1 = objects[1] --> Object
print(o1.id) --> (field) Object.id: integer

• any integer index on objects{} will return an Object type variable.
  they are all equal in terms of type
• therefore those objects can access an id field, which belongs to this Object class
• there is no such concept Object.1.id / Object.i.id
  the id field just belongs to the Object class, and has the same integer type