Is there a difference between setting the metamethod with __index = object and object itself?

[vxsqi]

Hi there, I was wondering if there was any difference when you set a table’s metatable with the metamethod __index = object and using just object itself.

See below as example:

local object = {}
object.__index = object

function object.new()
    local self = {}
    self.abc = 123

    setmetatable(self,{__index = object}) -- notice metamethod here
    return self
end

compared to:

local object = {}
object.__index = object

function object.new()
    local self = {}
    self.abc = 123

    setmetatable(self,object) -- notice it's just object and not __index = object
    return self
end

[DasKairo (Cairo)]

There is no difference, its just how the metatable is being applied.

So when you are applying the metatable in the second Argument, you are basically telling the code to create a metatable within that Array that has the __index metamethod inside, so basically this is what the second Example is:

Array = {__index = Array} -- Metamethod specified
-- Array.__index = Array is Basically the same thing as the line above.

setmetatable(self, Array) -- creates metatable from Array

Compared to the first:

Array = {}
-- doesnt require a specified metamethod

setmetatable(self, {__index = Array})
--[[
    Applies metatable without the Variable while creating a new table
    for the metatable.
--]]

The First method is more cleaner in my opinion, however it is up to you.