[issue22498] frozenset allows modification via -= operator

2014-09-25 Thread Ezio Melotti
Ezio Melotti added the comment: This doesn't modify f, it replaces it with a new frozenset: >>> f = frozenset({1, 2}) >>> f frozenset({1, 2}) >>> id(f) 3071990668 >>> f -= frozenset({1}) >>> f frozenset({2}) >>> id(f) 3066719340 Notice how the two ids are different. In other

[issue22498] frozenset allows modification via -= operator

2014-09-25 Thread James Paget
New submission from James Paget: The operator -= modifies a frozenset (this should not be possible), instead of signaling a TypeError. Contrast with the += operator. >>> f=frozenset([1,2]) >>> f frozenset([1, 2]) >>> f -= frozenset([1]) >>> f frozenset([2]) >>> f -= frozenset([2]) >>> f frozens