Re: [Python-ideas] Dict joining using + and +=

On Wed, Feb 27, 2019 at 9:34 AM George Castillo gmcastil@gmail.com wrote:

The key conundrum that needs to be solved is what to do for `d1 + d2` when

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there are overlapping keys. I propose to make d2 win in this case, which is what happens in `d1.update(d2)` anyways. If you want it the other way, simply write `d2 + d1`.

This would mean that addition, at least in this particular instance, is not a commutative operation. Are there other places in Python where this is the case?

Yes there are. 'a' + 'b' is not the same as 'b' + 'a'.

For non-numbers we only require + to be associative, i.e. a + b + c == (a + b) + c == a + (b + c).

That is satisfied for this proposal.