PEP 0448 – Additional Unpacking Generalizations

Re:PEP 0448 – Additional Unpacking Generalizations by kbd on Friday July 17, 2015 @11:08PM (#9906431)

I wonder why set operations were never supported for dictionaries.

a = b | c

makes perfect sense, vs:

a = b.copy()

a.update(c)

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Re:PEP 0448 – Additional Unpacking Generalizations by JoshTriplett on Saturday July 18, 2015 @12:21AM (#9906562)

b|c for sets is commutative; b|c for dictionaries is not. | is not strictly required to commute, but a | operator that does not commute is surprising behavior, and Python doesn't favor surprising behavior.

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Re:PEP 0448 – Additional Unpacking Generalizations by kbd on Saturday July 18, 2015 @12:57AM (#9906633)

Thanks! That's exactly what I figured was the reason.

Personally I'd have gone for the practicality beats purity side of things here, but oh well.

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Re:PEP 0448 – Additional Unpacking Generalizations by azernik on Saturday July 18, 2015 @04:13AM (#9906956)

I think this is a practicality concern; specifically, with regards to the UI, and following the rule of least surprise to keep user (i.e. programmer) confusion down.

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