[Python-ideas] Preserving **kwargs order

[Eric Snow]

On Thu, Apr 3, 2014 at 4:24 PM, Chris Angelico <rosuav at gmail.com> wrote:

> On Fri, Apr 4, 2014 at 6:14 AM,  <random832 at fastmail.us> wrote:
> > Iterating in insertion order would make the iteration completely
> > independent of the hashing algorithm. The hashing algorithm determines
> > what buckets each item goes in, but you don't _have_ to iterate in
> > bucket order, depending on your data structure. C#, for example, stores
> > items in an array [which are populated from a freelist of array slots
> > that don't have items in them, or sequentially at the end of the array
> > if there are no slots in the freelist] and the buckets as linked lists
> > within the array.
>
> However that's done, it implies additional storage beyond the
> straight-forward mapping, right? Python's dict implementation is
> *highly* optimized (which is necessary, given how much of Python is
> built on dicts), and any proposal that basically says "Every dict
> needs to keep track of insertion order, for the sake of the handful of
> cases where you actually care" is likely to have the aerodynamic
> qualities of a rock.
>

Raymond has a proposal (back-burnered?) for a compact dict implementation
that preserves order in iteration until the first deletion:

https://mail.python.org/pipermail/python-dev/2012-December/123028.html
https://mail.python.org/pipermail/python-dev/2013-May/126327.html

-eric
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