[luabind] How to create a Lua-defined subclass from C++

[Glen F. <hol...@gm...>]

Hi there, I've got subclassing working pretty well between Lua and C++.  So I have a C++ base class, and can create subclasses in Lua and instantiate them there, add them to my "world", have them traversed and their methods called from C++, etc.

What I don't understand how to do is how to create instances of Lua classes from C++.  Is this possible?  I have the name of the classes, because I call my own "register" method from Lua, so my app knows the names of available subclasses.  But how can I create a new instance of one of them from C++?

Lua:
	class 'Derived' (app.Base)

	function Derived:__init(str)
	    app.Base.__init(self, str .. " (Derived)")
	end

	app.registerSubClass('Derived')

Later on, in C++, I'd like to do the Lua equivalent of:
	x = Derived("hello")

Then I can do:
	world = app.getWorld()
	world:addObject(x)

All I can think of is something like:
	shared_ptr<Base> x = luabind::call_function<shared_ptr<Base> >(luaState, "createObject", "Derived", "hello");
	world->addObject(x);  // and so on...

Any ideas?  I can't just call new on my luabind::wrap_base - derived object, then register that with Lua/luabind somehow (and tell it what Lua subclass it should be using)?  (that would be nice ;-)

Thanks,
Glen.