[Python-Dev] Proposal: add odict to collections

[David Wolever]

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".