Chris Withers wrote:
>
> Chris Withers wrote:
> > Steve Alexander wrote:
> > > > Do you know if objects in PARENTS are acquisition wrapped?
> > > I'm pretty sure that they are.
> >
> > They are indeed, in fact, pretty much everything is :(
> > The only way to check if o is in PARENTS appears to be:
>
> > if o.aq_base in map (lambda o : o.aq_base,PARENTS):
>
> Hmm, is there anyway the Acquisition ExtensionClass(right thing? I'm not
> too hot here ;-) could be altered such that, if r1 and r2 are two
> different acquisition wrappers for the same object that:
>
> r1 == r2 and r1 in [r2,x,y]
>
> would return true?
Yes. I think that this would be a great idea.
Note that if r1 implements __cmp__, then it is called.
This means that you could implement the proposed behavior now
with:
def __cmp__(self, o):
return cmp(
id(getattr(self, 'aq_base', self)),
id(getattr(o, 'aq_base', self))
)
It also means that (with the proposed change) that '=='
will only be equivalent to an identity comparison if
an object doesn't define comparison. In most cases, however,
this shouldn't be a problem.
> It might be best to leave (r1 is r2) returning false as it does now so
> that you can actually tell if things aren't what you expected ;-)
Good, because there's no hook to override 'is'.
> PS: This question is still worrying me :(
>
> > 2. Is there any case where a Zope object isn't going to have a .aq_base
> > attribute?
Sure. There is no guarentee that all objects are wrapped.
A common idiot for dealing with this is getattr(o, 'aq_base', o).
So your example above would become:
if getattr(o, 'aq_base', o) in map (
lambda o : getattr(o, 'aq_base', o),
PARENTS)
I've considered implementing the aquisition attributes in
the Implicit and and explict base classes, which would probably
be a good idea.
Jim
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