Re: Register Lua callback functions from within Lua to C++

[Michael Bauroth <Michael.Bauroth@...>]

Hi, me once more. Have found out, that the code works very well (another 
error confused me here). The remaining question is, how to pass a 
additional parameter (in my special case the sender object), when I 
trigger the callback?

// push function
lua_rawgeti( L, LUA_REGISTRYINDEX, m_CbOnMouseDown );

// push parameter(s)
lua_rawgeti( L, LUA_REGISTRYINDEX, this );
// XXX doesn't work, needs an integer here  :(

// call function
if ( lua_pcall( L, 1, LUA_MULTRET, 0 ) != 0 )
{
    TRACE( _T( "Error calling LUA callback OnMouseDown\n" ) );
}

Best Regards
Micha

Michael Bauroth schrieb:
> Hi,
>
> normally Google is my friend, but this time I searched several hours but 
> without luck. What I'm looking for is a way, in which I can register 
> from Lua side a callback to C++ as a pointer like this:
>
> Lua:
>
> function OnMouseDown( btn )
>     -- do something
> end
>
> function createButton()
>     btn = Button:new()
>     btn:RegisterCallback( OnMouseDown )
>     return btn
> end;
>
> Button b1 = createButton()
>
>
> Button is a C++ class accessible from Lua. The class has a method 
> RegisterCallback(), which should take the Lua function pointer and store 
> it internally for later use. What I've found was something like this 
> (doesn't work til now):
>
> int FButton::RegisterCallback( lua_State *L )
> {
>     m_CbOnMouseDown = luaL_ref( L, LUA_REGISTRYINDEX );
>
>     return 0;
> }
>
> What I'm doing wrong?
>
> Any help is higly appreciated.
>
> Thanx in advance.
> Micha