[Zope-Coders] Changes to ZPublisher

[Sidnei da Silva]

On Wed, Oct 06, 2004 at 12:29:55PM -0400, Chris McDonough wrote:
| > Before the changes, exceptions on __bobo_traverse__ would not be
| > handled, so if a AttributeError would happen, it would pop up
| > untouched, resulting on a 500 response status, instead of 404.
| 
| Why is that a good thing?  Shouldn't it be up to the implementor to
| decide what should happen during bobo traverse?  If an exception happens
| that raises AttributeError or KeyError during __bt__, I don't think I
| want it to try something else.

I suppose you are referring to the stuff below here. As for converting
into a NotFoundError, Tres suggested to do it in ZPublisher, and
AttributeErrors not coming from __bobo_traverse__ are converted to
NotFound already.

| > It would also try __bobo_traverse__ only, if __bobo_traverse__ exists,
| > completely ignoring __getattr__ and __getitem__.
| 
| What makes it desirable to use __getattr__ and/or __getitem__ if the
| object has a __bobo_traverse__?

Simplifying __bobo_traverse__ implementation?

| > After my change, AttributeError and KeyError in __bobo_traverse__
| > will be converted to a NotFound, resulting in a 404 response status.
| 
| This seems like a bit more DWIM that would need to be carefully
| undocumented, like all the other DWIM. ;-)

The intention here is not introduce anything new, but to traversal
using __bobo_traverse__ behave the same way as attribute traversal
with regards to exceptions raised.

| > It will also continue looking through __getattr__ and __getitem__,
| > which is where the semantics really differ. I'm more worried about
| > changing the semantincs because there are other places where
| > __bobo_traverse__ is used, namely restrictedTravers on OFS.Traversable
| > and PageTemplates.Expressions.
| 
| I don't know if this is a win.

It's probably not, that's why I'm asking :)

| > This change would simplify the implementations of __bobo_traverse__,
| > which would not have to worry about looking at __getattr__ and
| > __getitem__ themselves, but I would like to know what people think
| > first.
| 
| I'm -1, FWIW.

Thanks!

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Sidnei da Silva <sidnei at awkly.org>
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