Lots and lots of people want ordered dicts it seems. Or at least, they want to be able to access their dictionary keys in order. It's in the FAQ (
http://www.python.org/doc/faq/programming.html#how-can-i-get-a-dictionary-to-display-its-keys-in-a-consistent-order) and has recently shown up as a recipe (
http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/438823).
I have lots of code that looks like:
keys = mydict.keys()
keys.sort()
It seems that there should be a more straight foreward way to address this extremely common use case. How about adding optional parameters to some of the dict methods that control the order that keys are returned?
For example, instead of the above lines, maybe make it:
keys = mydict.keys(sorted=True)
.items() could work the same way. It could probably work for .iterkeys() and .iteritems() as well, though the trivial implementation wouldn't save any memory over .keys().
Maybe we could even extend it to:
keys = mydict.keys(sorted=True, reversed=True) # of something...
It just seems that the community spends a lot of time working around this issue and there is a simple solution. (For a given definition of simple :)
The pros:
-Simple syntax that is fully backward compatible
-Seems like it would save a lot of effort in education and meet a community need
-Dicts are by definition unordered, "Although practicality beats purity."
The cons:
-May be difficult to implement the .iter*() methods efficiently.
What do y'all think?
Chris
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