[ZPT] python: path(request/foo) or 0

[Evan Simpson]

Tim Head wrote:
> i've got a question. in one of the examples(the file thingie) the start 
> varible has the value that is submited with the request or if left blank 
> defaults to 0. i tried to do they same in one of my pages with the 
> result that i end up with an error if the variable isn't submited with 
> the request.
> It seems the OR doesn't work.

I haven't been careful enough to keep the examples and docs in line with 
the current implementation :-(

For a while, "path('whatever')" in a Python expression would evaluate to 
an un-raised exception if the path failed to resolve.  This exception 
was false-valued, so the OR trick worked.  This was a Wrong Thing, and 
caused other problems.  The proper way to do this now is:

python:path('whatever | nothing') or 0

Cheers,

Evan @ Zope