Steven D'Aprano schreef: > If seq can be None as well as a sequence, doing a test "if len(seq) > 0" > won't save you because len(None) will fail. You need an explicit test > for seq being None: > > if seq is not None and len(seq) > 0 > > Or even better: > > if seq > > which Just Works regardless of the type of seq.
Yes, true. I agree that testing in a Boolean context works best in those cases. After a good night's sleep I remember why I felt uneasy doing it like that: I feel that 'if seq' should be synonym with 'if seq is not None', but I can't explain why. No rational reasons I think; it's probably just from being used to C and C++ where 'if (p)' in pointer contexts is used as synonym for 'if (p != NULL)'. In general I don't have too many problems using Python idioms instead of C or C++ idioms, but apparently sometimes my years of experience in these languages sometimes show trough in Python. Luckily my BASIC habits have died out long ago. -- If I have been able to see further, it was only because I stood on the shoulders of giants. -- Isaac Newton Roel Schroeven -- http://mail.python.org/mailman/listinfo/python-list
