PEP 584 – Add + and – operators to the built-in dict class

Re:PEP 584 – Add + and – operators to the built-in dict class by jessaustin on Wednesday March 06, 2019 @11:36AM (#19320184)

  >>> { 'a' : 1 } | { 'a' : 2 }

ISTM the most logical result would be:

  { 'a' : { 1, 2 } }

...but I could certainly understand throwing an exception.

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Re:PEP 584 – Add + and – operators to the built-in dict class by xiao_haozi on Wednesday March 06, 2019 @01:20PM (#19321182)

While I see your point, I don't think this makes sense historically. Dictionaries never supported such behavior before so you'd be introducing a new core concept to a dictionary. But moreover, you'd be changing the type of the value only on duplicated keys, and what about if you were to add another value of 2 to a? Are you making this a set, and why? I think it would come with too many caveats and assumptions in the PEP.

I'm not saying you have a bad idea/logic here, just that I'm not sure it's the best thing for the dict.

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Re:PEP 584 – Add + and – operators to the built-in dict class by dan-robertson on Wednesday March 06, 2019 @03:21PM (#19322381)

Note that this forgets the order of the arguments, which may not be desirable

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Re:PEP 584 – Add + and – operators to the built-in dict class by kqr on Wednesday March 06, 2019 @03:31PM (#19322451)

If the property we want to achieve is "a | b == b | a" we necessarily have to forget the order of the arguments.

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