[Python-Dev] Guarantee ordered dict literals in v3.7? (original) (raw)

Peter Ludemann pludemann at google.com
Sun Nov 5 15:50:12 EST 2017

Isn't ordered dict also useful for **kwargs?

If it turns out that there's a dict implementation that's faster by not preserving order, collections.UnorderedDict could be added. There could also be specialized implementations that pre-size the dict (cf: C++ unordered_map::reserve), etc., etc. But these are all future things, which might not be necessary.

On 5 November 2017 at 12:44, Sven R. Kunze <srkunze at mail.de> wrote:

+1 from me too.

On 04.11.2017 21:55, Jim Baker wrote: +1, as Guido correctly recalls, this language guarantee will work well with Jython when we get to the point of implementing 3.7+. On Sat, Nov 4, 2017 at 12:35 PM, Guido van Rossum <guido at python.org> wrote:

This sounds reasonable -- I think when we introduced this in 3.6 we were worried that other implementations (e.g. Jython) would have a problem with this, but AFAIK they've reported back that they can do this just fine. So let's just document this as a language guarantee.

On Sat, Nov 4, 2017 at 10:30 AM, Stefan Krah <stefan at bytereef.org> wrote:

Hello, would it be possible to guarantee that dict literals are ordered in v3.7?

The issue is well-known and the workarounds are tedious, example: https://mail.python.org/pipermail/python-ideas/2015-Decembe r/037423.html If the feature is guaranteed now, people can rely on it around v3.9.

Stefan Krah

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