On 2009-09-19, Christian Heimes <li...@cheimes.de> wrote: > kj wrote: >> For example, LBYL would look like this: >> >> if os.path.isfile(some_file): >> os.unlink(some_file) >> >> In contrast, EAFP would look like this: >> >> try: >> os.unlink(some_file) >> except OSError: >> pass > > > The two version aren't equal. The first one suffers from a race > condition which may lead to a severe security issue. The file may be > gone or replaced by a different file in the time span between the check > and the call to unlink().
IOW, just be cause you look before you leap, it doesn't mean you're not going to land on anybody and have to ask for forgiveness afterwards. Since you always have to handle the error case, there's not much point in checking first unless the error case has bad side-effects that you're trying to avoid. In this case, attempting to unlink a non-existent file has no bad side-effects, so there's no point in checking before the unlink. -- Grant -- http://mail.python.org/mailman/listinfo/python-list
