Steven Watanabe wrote: > PEP 8 says, "Comparisons to singletons like None should always be done > with 'is' or 'is not', never the equality operators." I know that "is" > is an identity operator, "==" and "!=" are the equality operators, but > I'm not sure what other singletons are being referred to here.
Other builtin singeltons are NotImplemented and Ellipsis, see: http://docs.python.org/ref/types.html for details. > > Also, I've seen code that does things like: > > if foo is 3: > if foo is not '': > > Are these valid uses of "is"? No. Try this examples: >>> a = 'spam' >>> b = ''.join(list(a)) >>> b 'spam' >>> a == b True >>> a is b False >>> a = 10000 >>> b = 10000 >>> a == b True >>> a is b False > > Thanks in advance. > -- > Steven. Hope this helps. Ziga -- http://mail.python.org/mailman/listinfo/python-list
