Daniel Nouri wrote:
> Ross Patterson wrote:
>> Daniel Nouri <[EMAIL PROTECTED]>
>> writes:
>>
>>> Martin Aspeli wrote:
>>>
>>>> Unfortunately, acquisition doesn't work properly inside Python property
>>>> __get__ accessors. I've seen this pattern before, but I've seen people have
>>>> various problems with it (that I can't remember the details of right now).
>>> Hmm, I've been using @property now for quite a long time for handling
>>> context without any problems. It would be good to have a minimal failing
>>> example.
>>>
>>> I know that formlib actions, which are applied via a decorator, have
>>> problems with acquisition. But then, they do much more than @property.
>> Here's a doctest showing what I think Martin was talking about:
>>
>> <snip>
>>
>> >>> foo.aq_parent
>> <Application at >
>> >>> foo.has_aq
>> True
>> >>> foo.has_aq_descr
>> True
>>
>> Those last two "True"s come out "False" if you actually run this test.
>>
>> It's a problem in all descriptors as far as I can tell. I'd be very
>> interested in any work arounds for this as I run into it all the time.
>>
>> Also, is there someplace this test might be included? Or is this
>> considered not to be a bug?
>
> Thanks for providing this clear example. I agree that it's a bug.
>
> I added a bit to the doctest, just to make sure that the acquisition
> wrapping of an attribute that's accessed in a descriptor (or property) is
> preserved:
>
> >>> foo.bar = SimpleItem('bar').__of__(foo)
> >>> foo.bar_property.aq_parent
> <Foo at />
> >>> foo.bar_descr.aq_parent
> <Foo at />
>
> For a view, this means that when returning context in a property 'context',
> the wrapping would be okay. This base class would thus do the "right thing"
> and also work if Acquisition would be fixed to also work in descriptors:
Some further experiments showed that this is not true. The call to
'self.context' will aq wrap the value returned by the context descriptor in
self. Thus making a context descriptor proves to be totally pointless. :)
--
http://danielnouri.org
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