[Python-3000] ordered dict for p3k collections? (original) (raw)

Adam Olsen rhamph at gmail.com
Fri Sep 14 19:50:34 CEST 2007

On 9/14/07, Mark Summerfield <mark at qtrac.eu> wrote:

On 2007-09-14, Nicko van Someren wrote: > On 11 Sep 2007, at 15:06, Mark Summerfield wrote: > > Is there any chance that an ordered dict will be added to Python 3's > > library? > > It would make sense, since one of the primary justifications for the > new metaclass system (PEP 3115) is to allow the metaclass to provide > order-preserving dictionaries to record the order in which members > are defined. > > > I think other people must find such things useful. There are three > > implementations on the Python Cookbook site, and one on PyPI, all in > > pure Python (plus I have my own implementation, also pure Python). > > Is there much commonality between the interfaces for these? I'm sure > there are various different opinions as to the exact nature of the > API, particularly around any facilities for re-ordering, slicing etc. > Cheers, > Nicko

After posting I realised that actually this isn't P3K-specific. I'd hope to see the collections module extended with more data structures in general. I put a similar post on the main python list but with no consensus so far... I put forward an API which is the same as dict (but any list or iterator returned "just happens" to work in key order) plus a few extra methods to exploit the ordering. I don't know how to refer to a usenet thread but this should get there:

That's a sorted dict. PEP 3115 wants an insertion-ordered dict. You're not the first to confuse them. ;)

-- Adam Olsen, aka Rhamphoryncus

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