a,b = 2,3 and [a,b] = [2,3]

[Chris Angelico]

On Tue, Sep 3, 2019 at 5:53 PM Serhiy Storchaka <storchaka at gmail.com> wrote:
>
> 02.09.19 12:24, Chris Angelico пише:
> > But the curious difference happens in 3.7. I don't know what changed
> > to cause this, but from there on, the list gets built and then
> > unpacked.
>
> This was a side effect of moving the optimization for `x in [a, b]` from
> the peepholer to the AST optimizer.
>

Ah ha. Thank you.

Is it worth trying to reinstate that? On the one hand, there's no
reason to build the list, and this technically is a (performance)
regression. On the other hand, it's not code people actually write,
since you can do the same thing with a tuple and it IS optimized.

ChrisA