[Zope3-dev] Re: calling interface returns object, calling queryAdapter returns None?

[Chris Withers]

All the following are great, especially the (SF) ones ;-)

Tres Seaver wrote:
>   >>> from zope.interface import Interface, Attribute
>   >>> from zope.interface import implements, directlyProvides
>   >>> from zope.component import provideUtility, provideAdapter, adapts
>   >>> class IFoo(Interface):
>   ...     name = Attribute(u'Name')
>   >>> class FooUtil:
>   ...     implements(IFoo)
>   ...     def __init__(self, name):
>   ...         self.name = name
>   >>> fooUtil = FooUtil('default')
>   >>> provideUtility(fooUtil)
>   >>> fooUtilNamed = FooUtil('named')
>   >>> provideUtility(fooUtilNamed, name='named')
>   >>> class FooAdapter:
>   ...     implements(IFoo)
>   ...     adapts(None)
>   ...     name = 'default'
>   ...     def __init__(self, context,*args):
>   ...         self.context = context
>   >>> class FooAdapterNamed(FooAdapter):
>   ...     name = 'named'
>   >>> provideAdapter(FooAdapter)
>   >>> provideAdapter(FooAdapterNamed, name='named')
> 
> Now the usage.  Things which *don't* work today are marked '(SF)'.
> 
> Interfaces called with *no* context argument return
> utilities, not adapters (SF)::
> 
>   >>> u_default = IFoo() # return the default utility
>   >>> u_default.__class__.__name__, u_default.name
>   ('FooUtil', 'default')
> 
> Named utilities can also be looked up (SF)::
> 
>   >>> u_named = IFoo(name='named')
>   >>> u_named.__class__.__name__, u_named.name
>   ('FooUtil', 'named')
> 
> Default adapter lookup works as expected::
> 
>   >>> context = object()
>   >>> a_default = IFoo(context)
>   >>> a_default.__class__.__name__, a_default.name
>   ('FooAdapter', 'default')
> 
> But we can also do named adapter lookup (SF)::
> 
>   >>> a_named = IFoo(context, name='named')
>   >>> a_named.__class__.__name__, a_named.name
>   ('FooAdapterNamed', 'named')

I'll note that none of these appear to do contextual lookup.
Would we want a spelling like this which worked with contextual lookup?

One thing I think I mentioned before would be the ability to use 
"calling the interface" to get a multi-adapter:

>>> provideAdapter(FooAdapter,adapts=(None,None))
>>> a_default = IFoo(objects=(context,context))
>>> a_default.__class__.__name__, a_default.name
('FooAdapter', 'default')

One other thing, where is the code that gets called when you do 
ISomething(..etc...)? I had a look in interface.py and couldn't find 
anything :-S

I'd be interested in knocking the above set of extras up on a branch and 
seeing what people think...

cheers,

Chris

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