[Python-Dev] os.path.walk() lacks 'depth first' option (original) (raw)

Guido van Rossum guido@python.org
Mon, 12 May 2003 21:44:41 -0400

How odd. I was going to say the reverse; that I always want to distinguish between the two, because TypeError almost invariably is a programming error of some kind, while AttributeError is nearly always an error that I'm checking in order to have a fallback. E.g.:

try: foo = thingy.foo except AttributeError: # default case else: foo() However, if 'thingy.foo' were to raise any other kind of error, such as a TypeError, it'd probably mean that thingy had a broken 'foo' descriptor that I'd want to know about.

This sounds like a much more advanced use, typical to a certain style of programming. Others would do this using hasattr() or three-argument getattr(); some will argue that you should have a base class that handles the default case so you don't need to handle that case separately at all (though that may not always be possible, e.g. when dealing with objects created by a 3rd party library).

Your example argues for allowing to distringuish between AttributeError and TypeError, but doesn't convince me that they are totally different beasts.

--Guido van Rossum (home page: http://www.python.org/~guido/)