Tim Peters wrote:
[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.
Rats, naturally I was thinking of "if not (a is b):"
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
regards
Steve
--
Steve Holden +1 571 484 6266 +1 800 494 3119
Holden Web LLC http://www.holdenweb.com/
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