[Zope3-dev] Re: __contains__ and acquisition problem?

[Florent Guillaume]

Jim, as the author of the Acquisition classes, could you comment on this?

Thanks,
Florent

Florent Guillaume wrote:
> Could anybody shed some light on what's happening here:
> 
>  >>> from Acquisition import Implicit
> 
>  >>> class Impl(Implicit):
> ...     pass
> 
>  >>> class C(Implicit):
> ...     def __getitem__(self, key):
> ...         print 'getitem', key
> ...         if key == 4:
> ...             raise IndexError
> ...         return key
> ...     def __contains__(self, key):
> ...         print 'contains', repr(key)
> ...         return key == 5
> 
> The class by itself behaves as expected:
> 
>  >>> c = C()
>  >>> 5 in c
> contains 5
> True
>  >>> 3 in c
> contains 3
> False
> 
> Let's put c in the context of i:
> 
>  >>> i = Impl()
>  >>> i.c = c
> 
> Now why is the following happening? Why is __contains__ not used?
> 
>  >>> 3 in i.c # c.__of__(i)
> getitem 0
> getitem 1
> getitem 2
> getitem 3
> True
>  >>> 5 in i.c
> getitem 0
> getitem 1
> getitem 2
> getitem 3
> getitem 4
> False
> 


-- 
Florent Guillaume, Nuxeo (Paris, France)   Director of R&D
+33 1 40 33 71 59   http://nuxeo.com   fg at nuxeo.com