[Michael Foord] >> ... >> Adding the following new asserts: >> >> ... >> assertNotIs (first, second, msg=None)
[Steve Holden] > Please, let's call this one "assertIsNot". +1 > I know it's valid Python to say > > if a not is b: Nope, that's a syntax error. > but it's a much less natural way of expressing the condition, and (for all I > know) might even introduce an extra negation operation. "is not" is, I > believe, treated as a single operator. "is not" and "not in" are both binary infix operators, not to be confused with the distinct use of "not" on its own as a unary prefix operator. "not is" and "in not" are both gibberish. >>> 1 is not 2 True >>> 1 is (not 2) False >>> 1 not is 2 SyntaxError: invalid syntax >>> 1 not in [2] True >>> 1 in not [2] SyntaxError: invalid syntax >>> 1 in (not [2]) Traceback (most recent call last): ... TypeError: argument of type 'bool' is not iterable _______________________________________________ Python-Dev mailing list Python-Dev@python.org http://mail.python.org/mailman/listinfo/python-dev Unsubscribe: http://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
