[Python-ideas] New PEP 550: Execution Context

[Guido van Rossum]

Thanks for the explanation. Can you make sure this is explained in the PEP?

On Aug 11, 2017 10:43 PM, "Yury Selivanov" <yselivanov.ml at gmail.com> wrote:

> > On Fri, Aug 11, 2017 at 10:17 PM, Guido van Rossum <guido at python.org>
> wrote:
> > > I may have missed this (I've just skimmed the doc), but what's the
> rationale
> > > for making the EC an *immutable* mapping? It's impressive that you
> managed
> > > to create a faster immutable dict, but why does the use case need one?
>
> > In this proposal, you have lots and lots of semantically distinct ECs.
> > Potentially every stack frame has its own (at least in async code). So
> > instead of copying the EC every time they create a new one, they want
> > to copy it when it's written to. This is a win if writes are
> > relatively rare compared to the creation of ECs.
>
> Correct. If we decide to use HAMT, the ratio of writes/reads becomes
> less important though.
>
> Yury
>
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