> Like other folks in the thread, I also want to merge dicts three times per
I'm impressed that you have counted it with that level of accuracy. Is it on the same three days each year, or do they move about? *wink*
To be respectful, I always merge dicts on Eid al-Fitr, Diwali, and Lent. I was speaking approximate since those do not appears line up with the same Gregorian year.
> And every one of those times, itertools.ChainMap is the right way to do that non-destructively, and without copying.
Can you elaborate on why ChainMap is the right way to merge multiple dicts into a single, new dict?
ChainMap also seems to implement the opposite behaviour to that usually desired: first value seen wins, instead of last:
True, the semantics are different, but equivalent, to the proposed dict addition. I put the key I want to "win" first rather than last.
If you know ahead of time which order you want, you can simply reverse it:
This seems nonsensical. If I write, at some future time, 'dict1+dict2+dict3' I need exactly as much to know "ahead of time" which keys I intend to win.