[Zope-dev] brain.getObject and traversal

[Florent Guillaume]

Chris Withers wrote:
>> You're mistaken. The old code did:
>>
>>   def getObject(self, REQUEST=None):
>>         """Try to return the object for this record"""
>>         try:
>>             obj = self.aq_parent.unrestrictedTraverse(self.getPath())
>>             if not obj:
>>                 if REQUEST is None:
>>                     REQUEST = self.REQUEST
>>                 obj = self.aq_parent.resolve_url(self.getPath(), REQUEST)
>>             return obj
>>         except:
>>             zLOG.LOG('CatalogBrains', zLOG.INFO, 'getObject raised an 
>> error',
>>                      error=sys.exc_info())
>>             pass
>>
>> Which effectively returns None.
> 
> 
> Interesting. Where did that code come from?

It's been there for longer than I've being doing Zope.
http://cvs.zope.org/Zope/lib/python/Products/ZCatalog/Attic/CatalogBrains.py?hideattic=1&content-type=text/vnd.viewcvs-markup&rev=1.1.4.4

>> All robust old code had to be able to test for None, because it was 
>> returned in many cases (when indexes got desynchronised, due to 
>> transaction bugs for instance, or manage_beforeDelete swallowing 
>> stuff, or conflict errors happening...). I know I had to add lots in 
>> my code.
> 
> Just because you had to do it in old code doesn't make it not evil. 
> Returning a meaningless value that masks a whole array of possible 
> distinct errors that should all be handled in different ways is mind 
> numbingly stupid IMNSHO. Why you feel so passionately that this should 
> be the case is beyond me. Do you like using bare try: except:s 
> throughout your code too?!

Well of course no, but I never had to check a getObject() against 
Unauthorized. Maybe it's because I only use it in a CMF setting where 
unaccessible objects are filtered anyway.

OTOH you're a bit excessive in your "Whole array of possible distinct 
errors".

>> Unauthorized in getObject is out of the question, that would be new 
>> behaviour.
> 
> Well, in 2.8, new behaviour is expected, right?
> I really passionately believe that we should not be returnining None in 
> Zope 2.8, and since 2.8 hasn't quite hit beta yet I'm very keen to see 
> it fixed asap.
> 
> Any objections?

I'm ok for 2.8. I'll look at it.

Florent

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