function Mesh3D.PaintRed(x)
        return 2*x;
end

function SafePointer(myPointer, myPointerType)
      return {Pointer = myPointer, PointerType = myPointerType);
end

TYPE_3ds =1000; -->Constant

function Mesh3D.New3ds(Filepath,p1,p2)
     
local     tempPointer = Mesh3D.Unsafe_New3ds(p1,p2);
      return SafePointer(tempPointer ,  TYPE_3ds};

end

function Render.3ds(My3ds, p1,p2,p3)
if (My3ds.PointerType= TYPE_3ds) then
Render.3ds(My3ds.Pointer,p1,p2,p3);
else
     Debug.MessageBox("Render.3ds was called by passing incorrect object. Only My3ds object should be passed. A pointer of type " .. My3ds.PointerType .. "was passed.");       

     end

end

Quote:Original post by Namatsu
1.) Yes this is possible Mesh3d would be a table in lua and because a function is a valid data type in lua this would be legal. The code below would also give you the same results

function chode(x)
return 2*x
end

Mesh3D.PaintRed = chode

Hopefully this helps.

2.)

I'm slightly confused as your safe pointer function doesn't actually check anything. I would actually suggest looking into a c++ solution where you have a class that encapsulates your pointer and the type and then all the objects that you actually pass around in lua will be pointers to a single class type. Then when you get the object in c++ you can do something like this.

// suto code below

CLuaSafePointer * pLSP = getdata();
if(pLSP.type == LSP_TYPEIWANT)
{
// do something
}
else
// throw error or ignore

Quote:
2): This seems like overkill to me. You want to check each and every function parameter to ensure its correctness? That adds a small penalty cost for one function, but to put it in all your functions the penalty cost will add up linearly to the # of calls you make.

I think the answer depends on what binding library (if any) you are choosing to use in your game. For example, Luabind uses an exception handling mechanism: link. Using existing functionality like that seems like a much less painful idea to me.

TYPE_3ds =1000; -->Constantfunction SafePointer(myPointer, myPointerType)      return {Pointer = myPointer, PointerType = myPointerType);endfunction Mesh3D.New3ds(Filepath,p1,p2)     local     tempPointer = Mesh3D.Unsafe_New3ds(p1,p2);      return SafePointer(tempPointer ,  TYPE_3ds};endfunction Render.3ds(My3ds, p1,p2,p3)if (My3ds.PointerType= TYPE_3ds) thenRender.3ds(My3ds.Pointer,p1,p2,p3);else     Debug.MessageBox("Render.3ds was called by passing incorrect object. Only My3ds object should be passed. A pointer of type " .. My3ds.PointerType .. "was passed.");            endendAirplaneMesh= Mesh3D.New3ds("MyPlane.3ds",34,2);Render.3ds(AirplaneMesh, 5,2,3); --> I am sure that AirplaneMesh is of type 3ds since I can check it's "PointerType" parameter.

Quote:Original post by Anonymous Poster

About No. 1) Could you please explain the table approach in order to define my functions with a dot in the middle like Mesh3D.PaintRed ? I am new to lua and I don't really get what you are saying...

did you previously define Mesh3D = {}? What about PaintRed?
or did you define Mesh3D = {PaintRed= myFunction} ?

Thanks so much everyone!
Cheers!
Rpd

Quote:Original post by Namatsu

as far as I know you cant have a '.' in a variable name, you are actually accessing a variable inside a table when you call Mesh3D.new in your script. having defined Mesh3D.new in c++, Mesh3D should be a table already. but if you were defining something purely in lua you would have to do the Mesh3D = {} first. Hopefully this explains things better.

Quote:Original post by Namatsu
correct

function Mesh3d.PaintRed(x)
return 2*x
end

should work