None or 0

Terry Reedy tjreedy at
Sat Sep 7 18:05:49 EDT 2002

To summarize Tim's thorough answer:
the language reference guarantees (specifies) the short-circuit
that you discovered.  It also guarantees that
> a = a or b
is *not* equivalent to
> if a is None:   a = b
unless *you* can guarantee that 'a' will never have a null value other
than None.

I add: as far as I know, both have been true since the beginning and
will remain true thru the 2.x series.  I would be extremely surprised
if anything changed thereafter.

Terry J. Reedy

More information about the Python-list mailing list