On Mon, 2005-07-11 at 17:47 -0400, Stevan Little wrote:

> I actually agree with you on that. But I would like to clarify it to 
> say that:
>    Foo.isa(Bar) # Foo.meta.isa(Bar) || Foo.meta.does(Bar)
> ... meaning that the .isa() which is supposed to be aliased into the 
> class from .meta is actually this.

I've always thought that .does() should check .isa() as well.  That's
how Class::Roles works in Perl 5.

If you *really* need to know that Bar inherits from Foo, there's .isa().
If all you really care about is that Bar is Liskov-a-rific with respect
to Foo, use .does(), which checks that Bar inherits from or does the
role of Foo, whether it mixes in any methods or not.

Have I mentioned before that I think you should be able to say:

class Foo
        method foo { ... }
        method more_foo { ... }

class Bar does Foo
        method foo { ... }

... probably get a compile-time error that Bar doesn't support

> I see a reason to differentiate between roles and classes on the 
> metalevel, but the argument is not as strong on the user-level.

I go further to see little reason to distinguish between role, class,
and type names (and what reason there is is for introspective
capabilities, not standard user-level type checking).

-- c

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