Signal Rebirthed

[Blequi]

I think you will have trouble implementing object orientation, as the language needs to be built ground up with that mind.

An option would be to follow the same trick used by __thiscall calling convention. An approach like this is used in Lua implementation of OO.

[DarkstaR]

I haven't gotten too far, since I've been busy the last few weeks. Everything I have is currently on the google code repo. I have some ideas for implementing OOP, but it is a bit tricky.

[jeremic]

An option would be to follow the same trick used by __thiscall calling convention. An approach like this is used in Lua implementation of OO.

I'm not too familiar with LUA, but as far as I recall OO was an afterthought in LUA as the language itself predates the "OOP boom". To me, OO in LUA seems like a big hack using tables. Is this correct?

[Blequi]

what I meant is that __thiscall basically inserts the "this" pointer as
the first argument in each instance method call from the class instance (pseudo code):

class SomeClass
{
    void SomeFunction(T1 param1, T2 param2, ...);
}

SomeClass c = new SomeClass();
c.SomeFunction(param1, param2, ...);

is basically

SomeFunction(SomeClass& this, T1 param1, T2 param2, ...);

SomeClass c = new SomeClass();
SomeFunction(c, param1, param2, ...);

In Lua, OOP has been implemented the same way using tables, just that the "this"
pointer we call "self"

local SomeClass = {}
SomeClass.__index = SomeClass

function SomeClass.SomeFunction(self, param1, param2, ...)
    ...
end

--[[
The same as:

function SomeClass:SomeFunction(param1, param2, ...)
    ...
end
]]

local c = setmetatable({}, SomeClass)
c:SomeFunction(param1, param2, ...)
-- The same as SomeClass.SomeFunction(c, param1, param2, ...)

Basically, both comes down to:

SomeFunction(SomeClass& this, T1 param1, T2 param2, ...);

[jeremic]

But that's cheating! That is the equivalent of calling C an object oriented programming language by passing structure pointers to functions and adding some syntactic sugar. How is inheritance and polymorphism implemented in LUA?

[Blequi]

But that's cheating!

well, it's tpforums :P

That is the equivalent of calling C an object oriented programming language by passing structure pointers to functions and adding some syntactic sugar.

yeah, Lua uses the ':Func' as syntatic sugar for the '.Func(self, ' and speed up the OOP coding.

How is inheritance and polymorphism implemented in LUA?

It's all about controling metamethods of the parent table. Basically, __index is the getter and __newindex is the setter function. There are more metamethods (aka methods to control its attached table) even to operator overloading like __add, __sub, __lt, __lt, __rt, __eq, __neq, ...

I'm a Lua lover, even though I think that implementation is ugly as hell (without proper keywords and so on), but as the Lua author said Lua is meant to be built from the ground up just with the table data structure. Probably that's the reason he stickied this way.