[Zope] Finding an object in a folder

[Paul Winkler]

On Wed, May 25, 2005 at 09:03:13PM +0100, Chris Withers wrote:
> >>if getattr(thefolder.aq_inner.aq_explicit,the_id,None):
> >
> >You are aware that this is in general *NOT* an emulation
> >of "hasattr".
> 
> I didn't say it was ;-)
> 
> >It may fail e.g. for properties.
> 
> How would it fail for properties?

Well, it doesn't distinguish between an attribute which doesn't exist 
and an attribute which has any false value.  This makes it unsuitable as
a hasattr() replacement IMHO.

It feels kind of hacky, but for this kind of thing I've used the "marker" 
pattern that you find throughout the Zope source:

marker = ()
if getattr(some_object, marker) is not marker:
    ...

-- 

Paul Winkler
http://www.slinkp.com