>>You should _never_ use 'is' to check for equivalence of value. Yes, due >>to the implementation of CPython the behaviour you quote above does >>occur, but it doesn't mean quite what you seem to think it does. > > > /me not checking for value. I'm checking for identity. Suppose "a" is a > constant. I want to check if "b" is the same constant.
/me too. That's what my example was all about. I was using identity to a known CONSTANT (in caps as per python naming conventions :-) to sidestep costly value equality computations. > By doing an "is" instead of a "==" you *can* catch some errors. > <snip> > By > testing with "is" you test for *that* integer, the one defined on your > module and that shouldn't go out of it anyway. I totally agree with you on this point. Anything that helps guarding against "stealthed" errors is a good thing by my standards. Cheers! /Joel Hedlund -- http://mail.python.org/mailman/listinfo/python-list
