Re: Lua 5 and tags

[Jamie Webb <j@...>]

On Mon, Jul 26, 2004 at 08:17:20AM -0700, Mark Hamburg wrote:
> If you can live with single-inheritance, my scheme using indices in the
> metatable will work with the type-testing technique used in Oberon. Single
> inheritance allows us to know that a class is at a particular depth in the
> inheritance tree. The metatable for a class can then include the appropriate
> light userdata for each class in its inheritance hierarchy. Testing for
> class membership then becomes something like:
> 
>     luaObj.metatable[ classInfo->depth ] == classInfo

You can do something rather similar that works with multiple
inheritance by checking something like:

luaObj.metatable[ pushlightuserdata(classInfo) ] == true

-- Jamie Webb