Hi

> Check out Python's new class heirarchy then. There is the standard 
> object
> system, using built in classes-metaclasses, and then one can easily 
> define
> their own metaclasses as needed.
>
> Singletons are extremely easy, as would a protoype based language be 
> too.
>
> I haven't played with the meta programming level in Python much, but 
> it's very
> powerful under there.

Having explicit metaclasses is easy but dangerous. Noury did that 
several times in Squeak, nathanael too. However, with two explicit 
metaclases and two simple naive methods we can break a complete system. 
I suggest you to read the excellent paper written by Noury Safe 
Metaclass Composition
OOPSLA'98

For me the metaclass limitation imposed by implicit metaclasses was the 
smartest choice
made at that time. Sure we pay the price with limited reuse but we have 
safety.

Now the future is bright because with traits we can solve a lot of the 
problems of metaclass composition by simply composing metaclass based 
on traits. We have a paper submitted on that topics if some of you are 
interested.