[Twisted-Python] Interfaces and adapters

[Andrew Bennetts]

On Fri, Aug 26, 2005 at 10:17:07AM +0400, en.karpachov at ospaz.ru wrote:
> Let's say we defined an interface and an adapter:
> 
> class IFoo(zope.interfaces.Interface):
>     pass
> 
> twisted.python.components.registerAdapter(Foo, Bar, IFoo)
> 
> As it is for now, the registerAdapter accepts any Foo, without regarding
> what it implements.

It has to accept pretty much anything -- adapters can be e.g. functions as
well as classes.

> Could somebody give any rationale why this condition shouldn't always hold:
> 
> foo = IFoo(bar)
> assert IFoo.providedBy(foo)
> 
> Seems it is not unreasonable to expect this behaviour, because it is
> exactly what interfaces are all about, or am I wrong?

That's a pretty reasonable expectation.  I think emitting a warning if this
doesn't hold would be a sane thing to do, and it wouldn't break any code.

-Andrew.