> From: [EMAIL PROTECTED] > > > > How could it not be an exception, in the plain English sense of the > > word? Most certainly you're asking for the index because you want to do > > something with the index. If the item is not found, you have no index, > > so that's a special case that must be handled separately. There is no > > logical difference between handling that special case in an except > > clause versus handling it with an if-branch. > > In my case of have done os.listdir() on two directories. I want to see > what files are in directory A that are not in directory B. > I have used exceptions in other languages and only do so on logic that > should never happen. In this case it is known that some of the files > will not be in both lists. I just want to know which ones. >
I think you may be confusing exceptions and assertions. Asserts are generally used to trap conditions that should not happen, while exceptions in Python are a standardized way to handle errors of all sorts. Where in C you would, say, open a file and check the return code to ensure that the file actually exists before using it, in Python you wrap the open statement in a try/except block instead. -- -Bill Hamilton -- http://mail.python.org/mailman/listinfo/python-list
