Re: Interesting C++ way to allocate user data (placement new)

[Leo Razoumov <slonik.az@...>]

On Wed, May 16, 2012 at 3:14 AM, Patrick Rapin <toupie300@gmail.com> wrote:
>
> One could then get a step further and specify the metatable registry
> name typically associated with the userdata.
>
> void * operator new( size_t size , lua_State * L, const char* metaname )
> {
>  void* obj = lua_newuserdata( L , size );
>  luaL_getmetatable(L, metaname);
>  lua_setmetatable(L, -2);
>  return obj;
> }
>
> So:
> Foo * foo = new ( L, "FooMetatable" ) Foo( constructor arguments );
>

To spare some typing one can define a corresponding macro:

// untested, targeting GCC
#define NEW(L, Type, args...)   (new(L, #Type "Metatable")Type(args))

Foo *foo = NEW(L, Foo, constructor arguments);

--Leo--