[z3-five] Re: Traversal issue [was: 0.2 release]

[Sidnei da Silva]

| I'm rather horrified such a thing should be necessary, and also 
| concerned about performance implications.
| 
| I'm confused why we need to do all this special work while Zope itself 
| does not. Zope doesn't have any code unwrapping the call stack just to 
| determine how the code was called, right? What's different here?

No 'sane' code seems to implement __bobo_traverse__. In fact, I
couldn't find a example of how it should look like. It's really
annoying that the consumers of __bobo_traverse__ expect it to always
return something and never raise an exception. 

An idea just occurred me: We could try to return an dummy object which
doesn't have __bobo_traverse__ and then:

- Raise NotFound when the object is published by ZPublisher
- Raise AttributeError/KeyError when restrictedTraverse tries to
  traverse further on that object.

That seems to be a bit cleaner, and doesn't break any assumptions made
by __bobo_traverse__.

-- 
Sidnei da Silva <sidnei at awkly.org>
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