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

Guido van Rossum guido at python.org
Fri Dec 15 10:53:40 EST 2017

Make it so. "Dict keeps insertion order" is the ruling. Thanks!

On Fri, Dec 15, 2017 at 2:30 AM, INADA Naoki <songofacandy at gmail.com> wrote:

> That's interesting information - I wasn't aware of the different > performance goals.

FYI, performance characteristic of my POC implementation of OrderedDict based on dict order are: * 50% less memory usage * 15% faster creation * 100% (2x) faster iteration * 20% slower movetoend * 40% slower comparison (copied from https://bugs.python.org/issue31265#msg301942 ) Comparison is very unoptimized at the moment and I believe it can be more faster. On the other hand, I'm not sure about I can optimize movetoend() more. If OrderdDict is recommended to be used for just keeping insertion order, I feel 1/2 memory usage and 2x faster iteration are more important than 20% slower movetoend(). But if either "dict keeps insertion order" or "dict keeps insertion order until deletion" is language spec, there is no reason to use energy and time for discussion of OrderedDict implementation. Regards, INADA Naoki <songofacandy at gmail.com>

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