Forgive me if this has already been discussed, but it seems to me that one could reduce the memory usage of dictionaries by 2/3 by removing the precomputed hash in each bucket.
Since Dictionaries only allow immutable objects as keys, one could move the precomputed hash into the keys. * Strings are probably the most popular keys for dictionaries and they already cache the hash (hmm that almost rhymes). * Numbers are trivial to hash. * For Tuples one could add a member to cache the hash. So why store the hash? I imagine it makes rebuilding the dictionary a bit quicker, since I guess you can avoid some comparisions since you know there are no duplicates. haven't looked at the code to see if it does that tho. and collision chains are possibly a bit quicker to traverse, tho I think python uses a mask instead of a mod by prime, so hash keys with the same low bits will collide, so collisions might be more common, but that's possibly fixable by using a congruential hash, but that's all black magic to me. -Kirat -- http://mail.python.org/mailman/listinfo/python-list
