Gabriel Genellina wrote:
Python doesn't require __add__ to be associative, so this should not be used as a general sum replacement.
It does not _require_ this, but using an __add__ that is not commutative and associative, or has side effects, would qualify as a serious misuse, anyway. So I think that this isn't a real disadvantage (it can always be documented that sum() expects __add__ to have these properties).
But you are right that summing floats with a requirement of high precision is a quite specific use case, so there are no serious arguments to do this, either.
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