Key-ordered dict in Python

Question

I am looking for a solid implementation of an ordered associative array, that is, an ordered dictionary. I want the ordering in terms of keys, not of insertion order.

Answer 1

Here is my own implementation:

import bisect
class KeyOrderedDict(object):
   __slots__ = ['d', 'l']
   def __init__(self, *args, **kwargs):
      self.l = sorted(kwargs)
      self.d = kwargs

   def __setitem__(self, k, v):
      if not k in self.d:
         idx = bisect.bisect(self.l, k)
         self.l.insert(idx, k)
       self.d[k] = v

   def __getitem__(self, k):
      return self.d[k]

   def __delitem__(self, k):
      idx = bisect.bisect_left(self.l, k)
      del self.l[idx]
      del self.d[k]

   def __iter__(self):
      return iter(self.l)

   def __contains__(self, k):
      return k in self.d

The use of bisect keeps self.l ordered, and insertion is O(n) (because of the insert, but not a killer in my case, because I append far more often than truly insert, so the usual case is amortized O(1)). Access is O(1), and iteration O(n). But maybe someone had invented (in C) something with a more clever structure ?