Userdata
From Legacy Roblox Wiki
A userdata is the type Lua uses for data structures in the underlying C program. There are no native Lua functions for handling those types, they must be handled via metatable. All Roblox objects are userdata Lua type.
Advanced
You can create a new userdata by passing true to the undocumented newproxy function. This userdata cannot be used for anything other than invoking functions via its metatable.
NOTE: newproxy is deleted for the time being, possibly permanently.
local NewUserData = newproxy(true) -- New userdata; Returns an empty metatable getmetatable(NewUserData).__index = {Name = "Foo", FooValue = "EPIC"} -- index MetaMethod print(type(NewUserData), NewUserData.Name, NewUserData.FooValue)
In the output window, you should see
userdata Foo EPIC
An equivalent functionality can be achieved in pure Lua:
function newproxy( src ) local obj = {} local mt if src == true then mt = {} elseif src then mt = getmetatable( src ) end setmetatable( obj, mt ) return obj end local NewUserData = newproxy(true) -- New userdata; Returns an empty metatable getmetatable(NewUserData).__index = {Name = "Foo", FooValue = "EPIC"} -- index MetaMethod print(type(NewUserData), NewUserData.Name, NewUserData.FooValue)
Output:
table Foo EPIC