[Python-ideas] A "local" pseudo-function

[David Mertz]

This doesn't address the fact no one actually needs it.  But if we WANTED a
sublocal() context manager, we could spell it something like this:

In [42]: @contextmanager
    ...: def sublocal(**kws):
    ...:     _locals = locals().copy()
    ...:     _globals = globals().copy()
    ...:     for k, v in kws.items():
    ...:         if k in locals():
    ...:             exec(f"locals()['{k}'] = {v}")
    ...:         elif k in globals():
    ...:             exec(f"globals()['{k}'] = {v}")
    ...:     yield
    ...:     locals().update(_locals)
    ...:     globals().update(_globals)
    ...:

In [43]: a = 42

In [44]: with sublocal(a=43):
    ...:     showa()
    ...:
43

In [45]: showa()
42

In [46]: with sublocal():
    ...:     a = 41
    ...:     showa()
    ...:
41

In [47]: showa()
42

On Sun, Apr 29, 2018 at 4:20 PM, Tim Peters <tim.peters at gmail.com> wrote:

> [Ethan Furman <ethan at stoneleaf.us>]
> > If we need a sublocal scope, I think the most Pythonic* route to have it
> > would be:
> >
> >     with sublocal():
> >         blah blah
> >
>
> As covered most recently in an exchange with Tim Delaney, best I can
> tell absolutely nobody has wanted that.  By "sublocal scope" they
> don't mean a full-fledged new scope at all, but a kind of limited
> "shadowing" of a handful of specific, explicitly given names.  It acts
> like a context manager, if there were a way to clearly spell
>


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