Raymond Hettinger wrote:
I don't favor one over the other. Am just pointing-out that the proposal is a little more complex than simply wishing for an ordered verion of a dictionary and expecting that that wish is self-defining in a way the matches everyone's intuition, use cases, and expectations.
If you have an odict with first-insertion ordering, it's fairly trivial to convert it to a dictionary with last-insertion ordering:
class odictlastinsertion(odict): def __setitem__(self, k, v): self.pop(k, None) self[k] = v
As you note, going the other way would be rather difficult, suggesting that the version ordered by the first key insertion is the more fundamental structure.
A PEP would definitely be needed to thrash out those kind of issues and decisions though