[Zope-dev] brain.getObject and traversal

[Chris Withers]

Florent Guillaume wrote:
> 2. is necessary for backward compatibility. *all* the previous 
> implementations of getObject returned None in case of problems.

This is the only bit I'm asking about, I accept that I'm in the insane 
minority on the other point ;-)

Just because that's what it did before doesn't mean we should leave it 
like that. I can see absolutely no benefit in returning None over 
raising a specific error.

Also, the original behaviour of getObject, prior to Casey's drastic and 
unexpected switch to restrictedTraverse(path,None) was to raise 
Unauthorized, NOT to return None.

I first became aware of Casey's changes when I upgraded a production 
Zope instance and started getting loads of random attribute errors where 
  I'd happilly been dealing with the Unauthorized's before.

So, for me, returning None is just plain evil. All it serves to do is 
mask an exception that's likely to be useful. If people are relying on 
it returning None, then it's a one line change in their code.

Now, the other problem I have with this fix is no tests were checked in 
for this. We should have tests that verify this behaves as it should, 
since those tests are likely to be the only formal documentation this 
issue ever receives ;-)

Would anyone object if I wrote tests and changed the implementation to 
raise exceptions, including Unauthorized, instead of returning None?

cheers,

Chris

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