Question

Currently I have something in lua that is like OOP using tables.

TCharacterController = {}
TCharacterController.speed = 10.0
TCharacterController.axis = "x"

function TCharacterController:new(o)
    o = o or {}
    setmetatable(o, self)
    self.__index = self
    return o
end

function TCharacterController:update()
    --this is a function that is called by the C application
end

The concept is that I will create a child object

ScriptObj = TCharacterController:new()

for each script instance attached to an object in my application (this is for a game). So I have an entity layer and all of the entities will have the ability to have a ScriptObj attached to them. My idea is that the Script is actually a class and it is instantiated for each entity it is attached too.

My question is, how do I instantiate the instance of the TCharacterController using the C API?

Answer 1

Since new is using the self reference syntatic sugar, you need to pass self as the first arg, the rest is just a function call of a table lookup:

lua_getglobal(L, "TCharacterController"); /* get the table */
lua_getfield(L, -1, "new");  /* get the function from the table */
lua_insert(L, -2); /* move new up a position so self is the first arg */
lua_pcall(L, 1, 1); /* call it, the returned table is left on the stack */