Simon Forman wrote: > On Jul 2, 3:57 pm, Scott David Daniels <scott.dani...@acm.org> wrote: >> Duncan Booth wrote: >>> Simon Forman <sajmik...@gmail.com> wrote: >>>> ... >>>> if self.higher is self.lower is None: return >>>> ... >>> As a matter of style however I wouldn't use the shorthand to run two 'is' >>> comparisons together, I'd write that out in full if it was actually needed >>> here. >> Speaking only to the style issue, when I've wanted to do something like >> that, I find: >> >> if self.higher is None is self.lower: >> ... >> >> more readable, by making clear they are both being compared to a >> constant, rather than compared to each other. > > I was going to do it that way for aesthetics if nothing else, but in > this particular code "self.higher is self.lower" could only have been > True if they were both None, so the final "is None" was redundant and > I only included it as a "just-in-case" check in case someone someday > used the code in such a way as to assign the same object (not None) to > both self.higher and self.lower... Totally pointless, I'm sorry to > say. I'm glad the whole line was redundant really. >
I say, you should keep the `is None` for readability and to safe guard against immutable optimization and/or Singleton objects. Due to an implementation detail, python does not guarantee that two immutable object will return different objects; you have: >>> a = 1 >>> b = 1 >>> a is b True -- http://mail.python.org/mailman/listinfo/python-list
