[Python-Dev] performance of {} versus dict()

Stephen J. Turnbull stephen at xemacs.org
Thu Nov 15 03:28:45 CET 2012

Chris Angelico writes:

 > >>> {"a":1}+{"b":2}

 > It would make sense for this to result in {"a":1,"b":2}.

The test is not "does this sometimes make sense?"  It's "does this
ever result in nonsense, and if so, do we care?"

Here, addition is usually commutative.  Should {'a':1}+{'a':2} be the
same as, or different from, {'a':2}+{'a':1}, or should it be an error?

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