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

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

I used the Lunar template for this. I will try to find it out, but for a 
newbie this thingie could be a little bit tricky (I guess I have no 
chance) :)

any hint?

Or would it be better to open a new thread, because this one has a 
different title and is initiallyl solved?

Best Regards
Micha

Jan de Vos schrieb:
> You need the correct metatable to be set on you userdata object.
>
> If you are not using any binding framework (such as tolua++ or luabind),
> you might be able to take a look at how the Button:new() function is
> implemented. Do the same in your code, and it will work :-)
>
> If you have no idea of how the Button:new() function was implemented,
> chances are that its programmer used some binding framework or other.
> The answer to your question greatly depends on that, so please try to
> find out.
>
>
> Jan
>
> > -----Original Message-----
> > From: lua-bounces@bazar2.conectiva.com.br 
> > [mailto:lua-bounces@bazar2.conectiva.com.br] On Behalf Of 
> > Michael Bauroth
> > Sent: maandag 10 november 2008 15:35
> > To: Lua list
> > Subject: Re: Register Lua callback functions from within Lua to C++
> >
> > Unfortunately this doesn't do the trick :(
> >
> > Let us reduce the complexity of the problem even more ...
> >
> > Primary I create an C++ object Button in Lua:
> >
> > btn = Button:new()
> > btn.RegisterCallback( callback )
> >
> > In C++ I store the reference ...
> >
> > m_CbOnMouseDown = luaL_ref( L, LUA_REGISTRYINDEX );
> >
> >
> > Later on I want to call a function from C++ in Lua like this:
> >
> > callback( btn )
> >
> > where btn should be of type Button again, so that I can call 
> > additonal 
> > C++ methods on it. I don't use any binding framework at the moment.
> >
> >
> > // push function
> > lua_rawgeti( L, LUA_REGISTRYINDEX, m_CbOnMouseDown );
> >
> > //push parameter(s)
> > //lua_pushlightuserdata( L, this );
> > //lua_pushvalue(L, 1);
> > 			
> > // call function
> > if ( lua_pcall( L, 1, LUA_MULTRET, 0 ) != 0 )
> > {
> >      // error
> > }
> >
> > pushlightuserdata has the disadvantage to give me only type free data.
> > Were should I embed the call to pushvalue instead?
> >
> > Best Regards
> > Micha
> >
> >
> >
> > Peter Cawley schrieb:
> > > It depends on which Lua/C++ binding framework you're using, but I'd 
> > > guess that a copy of the Lua-ized 'this' pointer will be at 
> > stack index 
> > > 1, and so you could use lua_pushvalue(L, 1); to push a copy 
> > of it to the 
> > > top of the stack.