[Zope3-dev] Proposal: Improving on __implements__

[Phillip J. Eby]

At 11:15 AM 1/19/03 +0200, Steve Alexander wrote:
>However, I still need the registry to make declarations for builtin 
>classes and other classes where the class object itself is immutable.

Doesn't that registry (typeImplements) already exist?


>I'd rather spell this as below, to get rid of the class.__implements__:
>
>   declareImplements(ServiceSubscriberEventChannel, IBindingAware)
>   declareImplementsLike(ServiceSubscriberEventChannel,
>                         EventChannel, SubscriptionTracker)

And the 'implements()' in the class body isn't a "declaration", 
too?  ;)  Perhaps the "magic" one should be called 
'instancesImplement()'.  The bare word 'implements' is a lousy name for an 
API, even for what it means now.


>I'd like to remove all reference to an '__implements__' attribute from 
>regular code.

I'm +1 on that *goal* - just not necessarily via the spelling I've seen so far.

Here's a crazy one:

class Foo(Bar, implements(Baz, Spam, interfacesOf(Thingy))):
     ...

It's of course crazy because it's going to mess with the MRO of the 
result.  But it's closest to simulating a Java-style "implements" 
clause.  I don't care for a bare 'implements' in the body of the class, but 
it just might work in the bases.  But I don't think it's worth the cost of 
(up to) doubling the length of the MRO.