[Zope3-dev] Twisted framework refactored

[Steve Alexander]

Phillip J. Eby wrote:
> 
> The difference, for anyone who cares, is that Twisted specifically 
> considers '__implements__' to be a *class* attribute, not an instance 
> attribute. 

I'd say __implements__ should be an object attribute. So, a module can 
implement something. An object() can implement something, by setting 
appropriate attributes on it, and setting its __implements__ attribute.

In Python 2.2, a function can implement something:

 >>> from Interface import Interface
 >>> l = lambda: 1
 >>> l.__dict__['__implements__'] = Interface
 >>> l.__implements__
<Interface Interface._Interface.Interface at 81a94a4>
 >>>


Specifically considering __implements__ to be a class attribute is 
wrong, as it adds an unnecessary dependency between the type of an 
object, and its contractual obligations.


--
Steve Alexander