[Zope-dev] adapting to None

[Chris Withers]

Dieter Maurer wrote:
> Then, use something different from adaptation (as adaptation does
> not fit your wishes).

This is what I'm trying to do with subclassing, and my question was why 
that subclassing wasn't working...

> I expect that your adapter factory can raise "ComponentLookupError"
> when it cannot handle the adaptation and then the "default" argument
> of the adapter lookup will take effect.
> 
>    adapter = IMyInterface(obj, None)

...which might work, except I'd want that None to be the default and 
with no need to specify it.

The pythonic way to do this would be to make IMyInterface a subclass of 
Interface (which it is) and tweak the implementation of whatever 
implements IMyInterface(...), which is exactly what I'm trying to do.

 From looking at the python implementation of Interface, __call__ is 
indicated to be the method to override, but with the C-based Interface, 
this has no effect. Why is that?

*That's* what I'm looking for help with, not judgement on whether 
adapting to None is a good idea or not ;-)

Chris

-- 
Simplistix - Content Management, Zope & Python Consulting
            - http://www.simplistix.co.uk