On Fri, Feb 28, 2014 at 4:39 PM, Mark H. Harris <harrismh...@gmail.com> wrote: > On Thursday, February 27, 2014 10:43:23 PM UTC-6, Chris Angelico wrote: > >> Simple rule of thumb: Never use 'is' with strings or ints. They're >> immutable, their identities should be their values. Playing with 'is' >> will only confuse you, unless you're specifically going for >> introspection and such. > > Right. The only time I use "is" is when I'm trying to explain to someone > new to python assignment what is happening inside... what Mark Summerfield > calls "python's beautiful heart," in his his recent book, "Programming in > Python 3" ... a great resource, by the way. >
'is' can and should be used with mutables, to distinguish between identical values with different identities. It's also appropriate to use 'is' with special singletons like None. Just be careful of ints and strings. ChrisA -- https://mail.python.org/mailman/listinfo/python-list
