[Python-Dev] Update on PEP 523 and adding a co_extra field to code objects

[Brett Cannon]

On Tue, 30 Aug 2016 at 11:56 Serhiy Storchaka <storchaka at gmail.com> wrote:

> On 30.08.16 21:20, Antoine Pitrou wrote:
> > On Tue, 30 Aug 2016 18:12:01 +0000
> > Brett Cannon <brett at python.org> wrote:
> >>> Why not make it always a list?  List objects are reasonably cheap in
> >>> memory and access time... (unlike dicts)
> >>
> >> Because I would prefer to avoid any form of unnecessary performance
> >> overhead for the common case.
> >
> > But the performance overhead of iterating over a 1-element list
> > is small enough (it's just an array access after a pointer dereference)
> > that it may not be larger than the overhead of the multiple tests and
> > conditional branches your example shows.
>
> Iterating over a tuple is even faster. It needs one pointer dereference
> less.
>

I'll talk it over with Dino and see what he thinks.


>
> And for memory efficiency we can use just a raw array of pointers.
>

I would rather not do that as that leads to having to track the end of the
array, special memory cleanup, etc.
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