[Python-Dev] Proposal: add odict to collections (original) (raw)

David Wolever wolever at cs.toronto.edu
Sun Jun 15 06:59:51 CEST 2008

On 14-Jun-08, at 8:39 PM, Armin Ronacher wrote:

... I noticed lately that quite a few projects are implementing their own subclasses of dict that retain the order of the key/value pairs. ... I'm +1 on this one too, as there are at least a couple of times in
recent memory when I would have found this useful.

And, as far as questions about the definition of an ordered
dictionary, is there any good reason not to simply treat the dict as
a list? Something like (with the obvious bits left out):

class odict(dict): def init(self, *args): self._order = [] def setitem(self, key, val): if key not in self:
self._order.append(key) def iter(self): return self._order def items(self): return ([item, self[item] for item in self._order]) def sort(self): self._order.sort() ... and so on ...

That way all the order-related functions are well defined, so it
would be hard claim that it doesn't do the "right thing" without
claiming that lists don't do the "right thing".

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