[Python-3000] ordered dict for p3k collections?

[Mark Summerfield]

On 2007-09-25, you wrote:
> On 9/25/07, Mark Summerfield <mark at qtrac.eu> wrote:
> > My proposal was for the sorteddict to be put in the collections module,
> > not as a builtin. One of the things I particularly like about Python is
> > that the core language is small.
> >
> > However, I think that the collections module is rather thin, and as you
> > say, it is "obscure" so won't get in the way of inexperienced or casual
> > users if it is beefed up a bit, yet could be really useful to more
> > demanding users.
> >
> > On comp.lang.python, a respondent called Paul Hankin suggested a
> > somewhat different approach to mine: he proposed a sorteddict with the
> > same API as a dict but with a constructor that is similar to the
> > sorted() function:
> >
> >     sorteddict((mapping | sequence | nothing), cmp=None, key=None,
> >                reverse=None)
> >
> > He points out that this has a problem with keyword argument
> > dictionaries, but that one solution is sorteddict(dict(**kwargs), ...).
>
> Why would this be a problem? There is no requirement that sorteddict()
> support this feature.
>
> > From comments other people have made on this list and on
> > comp.lang.python, it may be that Paul Hankin's approach is more popular
> > and better than the one I proposed---the only downside being that he
> > didn't give any hints as to an implementation.
> >
> > I am hoping that Python 2.6 (and 3.0) will have a sorted dictionary of
> > some kind, and I get the impression that it would be welcomed (in the
> > standard library).
>
> For that to happen, someone has to write a production-quality
> implementation, release it as a separate 3rd party module for a while,
> show that it is sufficiently stable and popular to be incorporated in
> the standard library, and commit to maintaining it for a few years at
> least. (It doesn't have to be all the same someone.)

OK, I'm sure I or Paul Hankin or others will put up at least one version
on PyPI and maybe get it in for Python 4:-)

> Hoping and wishing doesn't cause working code to spring into existence.

As a matter of fact it does... by the time I read this Paul Hankin had
written a version based on his idea... and so have I. Neither is likely
to be fast but they both provide the API described above in pure Python.

-- 
Mark Summerfield, Qtrac Ltd., www.qtrac.eu