[Python-Dev] Proposal: add odict to collections

Nick Coghlan ncoghlan at gmail.com
Sun Jun 15 10:03:02 CEST 2008

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


Nick Coghlan   |   ncoghlan at gmail.com   |   Brisbane, Australia

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