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[Python-ideas] PEP draft: context variables

Yury Selivanov yselivanov.ml at gmail.com
Tue Sep 5 13:43:57 EDT 2017 
On Tue, Sep 5, 2017 at 10:31 AM, Koos Zevenhoven <k7hoven at gmail.com> wrote:
> On Tue, Sep 5, 2017 at 8:24 PM, Yury Selivanov <yselivanov.ml at gmail.com>
> wrote:
>>
>> On Tue, Sep 5, 2017 at 9:12 AM, Koos Zevenhoven <k7hoven at gmail.com> wrote:
>> > On Tue, Sep 5, 2017 at 6:53 PM, Yury Selivanov <yselivanov.ml at gmail.com>
>> > wrote:
>> >>
>> >> On Tue, Sep 5, 2017 at 8:35 AM, Koos Zevenhoven <k7hoven at gmail.com>
>> >> wrote:
>> >> > On Tue, Sep 5, 2017 at 3:49 AM, Nathaniel Smith <njs at pobox.com>
>> >> > wrote:
>> >> [..]
>> >> >>
>> >> >> I think PEP 550 is sufficient to allow implementing all
>> >> >> your proposed APIs (and that if it isn't, that's a bug in PEP 550).
>> >> >
>> >> >
>> >> > That's not true either. The LocalContext-based semantics introduces
>> >> > scope
>> >> > barriers that affect *all* variables. You might get close by putting
>> >> > just
>> >> > one variable in a LogicalContext and then nest them, but PEP 550 does
>> >> > not
>> >> > allow this in all cases. With the addition of PEP 521 and some
>> >> > trickery,
>> >> > it
>> >> > might.
>> >>
>> >> I think you have a wrong idea about PEP 550 specification.  I
>> >> recommend you to reread it carefully, otherwise we can't have a
>> >> productive discussion here.
>> >>
>> >
>> > I'm sorry, by LocalContext I meant LogicalContext, and by "nesting"
>> > them, I
>> > meant stacking them. It is in fact nesting in terms of value scopes.
>>
>> I don't actually care if you use the latest terminology.  You seem to
>> have a wrong idea about how PEP 550 really works (and its full
>> semantics), because things you say here about it don't make any sense.
>
>
> In PEP 550, introducing a new LogicalContext on the ExecutionContext affects
> the scope of
> any_
> var.set(value) for *
> any
> *
> any_var
> .
> Does that not make sense?

It does. But your other sentence ".. You might get close by putting
just one variable in a LogicalContext and then nest them, but PEP 550
does not allow this in all cases .." does not.

Yury
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