Chetan wrote: >> Steven D'Aprano wrote: >> > On Sat, 28 Oct 2006 03:13:42 +0100, Steve Holden wrote: >> > >> >>> Finally, while True/False is a good mental mapping for numeric >> >>> comparisons, >> >>> take the following: >> >>> >> >>> >>> if "Cliff is a pillar of the open source community": >> >>> .... print "thank you" >> >>> .... else: >> >>> .... print "bugger off" >> >>> >> >>> bugger off >> >>> >> >> First off, even though nobody has called me on it, this example really prints >> "thank you", not "bugger off". I got confused in my cutting and pasting. >> Sorry about that. >> >> >> >>> Clearly this is not true. (Google Cliff/Dyer open source: only 11 >> >>> hits.), >> >>> but the string is *something* so the if block gets evaluated. >> >>> >> >> >>> if "The above example was bollocks": >> >> ... print "You don't know what you are talking about" >> >> ... else: >> >> ... print "Sorry: of course you are perfectly correct" >> >> ... >> >> You don't know what you are talking about >> > Cliff is making a point about semantics, and he's absolutely correct about >> > it, although it is irrelevant since we're talking about two-value logic >> > not semantics. >> Cheers, >> Cliff > > I am joining after some network downtime here, so I seem to have missed what > the real issue here is. At the risk of being completely irrelevant to the > discussion here, I think it doesn't seem to be just about something or > nothing - is None something or nothing? It seems to be neither:
If is, of course, nothing. You may have misunderstood the semantics of the "and" and "or" operators. >>>> None >>>> None and True >>>> None or True > True >>>> None and False >>>> None or False > False >>>> False or None >>>> False and None > False >>>> True and None >>>> True or None > True >>>> not None > True x and y | x something | x nothing --------------------------------------- y something | y | x y nothing | y | x x or y | x something | x nothing --------------------------------------- y something | x | y y nothing | x | y Georg -- http://mail.python.org/mailman/listinfo/python-list
