Guido van Rossum <gu...@python.org> added the comment:
I think for `|=` the only choice is for it to be essentially an alias to `.update()`. So that means `cm |= other` becomes `cm.maps[0].update(other)`. For `|` we are breaking new ground and we could indeed make `cm | other` do something like `ChainMap(other, *cm.maps)`. I've not used ChainMap much (though I've seen some code that uses it) so I'm probably not the best judge of whether this is a good feature to have. Note that `other | cm` will just do whatever `other.__or__` does, since ChainMap isn't a true subclass of dict, so it will not fall back to `cm.__ror__`. Basically ChainMap will not get control in this case. Other thoughts: - Maybe `cm1 | cm2` (both ChainMaps) ought to return `ChainMap(*cm2.maps, *cm1.maps)`? - These semantics make `|=` behave rather differently from `|`. Is that okay? If not, which of them should change, and how? ---------- _______________________________________ Python tracker <rep...@bugs.python.org> <https://bugs.python.org/issue36144> _______________________________________ _______________________________________________ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
