[Zope3-dev] Re: wildcard adapter

[Tres Seaver]

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Chris Withers wrote:
> Marius Gedminas wrote:
>> Now when you try to adapt anything to ITest, zope.component will call
>> your ``adapter`` function and then check the return value.  A return
>> value of None means "the adapter is not available", and results in a
>> TypeError you see here:
> 
> Yes, apologies, both you and Philipp are correct, I was trying to show a 
> simple version of a problem and oversimplified.
> 
> Here's what I really meant:
> 
>  >>> from zope.component import provideAdapter
>  >>> from zope.interface import Interface
>  >>> from zope.component import getMultiAdapter
>  >>> class ITest(Interface): pass
> ...
>  >>> def adapter(*args): return args
> ...
> 
>  >>> provideAdapter(adapter,adapts=(None,),provides=ITest)
>  >>> ITest(1)
> (1,)
> 
> Yay, as expected...
> 
>  >>> getMultiAdapter((1,),ITest)
> (1,)
> 
> Good, still works...
> 
>  >>> provideAdapter(adapter,adapts=(None,None),provides=ITest)
>  >>> getMultiAdapter((1,1),ITest)
> Traceback (most recent call last):
> ...
> zope.component.interfaces.ComponentLookupError:
>   ((1, 1), <InterfaceClass __main__.ITest>, u'')
> 
> Oh dear, what have I done wrong here?

The "order" of your adapter registration is *one*, but you are trying to
look it up against *two* objects (like a view).


Tres.
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Tres Seaver          +1 540-429-0999          tseaver at palladion.com
Palladion Software   "Excellence by Design"    http://palladion.com
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