On Sat, May 29, 2021 at 06:54:15PM +0200, Marco Sulla wrote:
> Since `dict` now is ordered, how about a `sort()` method?
> It could have the same signature of list.sort(), with an optional
> parameter "by" that can be "keys" or "values" ("keys" could be the
> default).
Dicts keep their insertion order stable, that doesn't mean that they are
sortable. They aren't lists where you can just reorder items, the
implementation is more complex than a simple list of (key,value) pairs
that can be sorted.
My understanding of the implementation is that the only practical way to
sort a dict is to sort the items ahead of time and then build it.
I don't know the current implementation, but I think it *might* be
something like Raymond Hettinger's proposal for a compact,
order-preserving, key-sharing dict:
https://mail.python.org/pipermail/python-dev/2012-December/123028.html
If you can think of a way to sort something like that, without changing
the way hash lookups work, and more efficiently than just sorting the
items and building a new dict, remember that the implementation can
change at any time.
The bottom line here is that *dicts aren't lists* and it doesn't make
sense to sort them. If you want a sortable data structure, stick to a
list or a tree, or a specialised data structure designed for the task.
--
Steve
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