On Sun, Apr 29, 2018 at 9:28 PM, Tim Peters <tim.pet...@gmail.com> wrote:
> [David Mertz <me...@gnosis.cx>]
> > Ooops. My proof [of] anti-concept has a flaw. It only "shadows" names
> that
> > already exist. Presumably that's the wrong idea, but it's easy enough to
> > change if desired.
>
> with sublocal(a=6):
> g("first in block")
> a = 5
> g("set a to 5")
> b = 19
> g("set b to 19")
> g("after")
>
> Worm around that too, then going back to the example at the top, if
> the manager's
>
> locals().update(_locals)
>
> had the intended effect, it would end up restoring `b` to 2 too, yes?
> The only names that "should be" restored are the names in the `kws`
> dict.
>
Actually, that wasn't my intention. As I imagined the semantics, I wanted
a context manager that restored the "outside" context for anything defined
"inside" the context. Allowing keyword arguments was just an extra
"convenience" that was meant to be equivalent to defining/overwriting
variables inside the body. So these would be equivalent:
## 1
with sublocal():
a = 1
b = 2
x = a + b
# a, b now have their old values again
## 2
with sublocal(a=1, b=2):
x = a + b
# a, b now have their old values again
## 3
with sublocal(a=1):
b = 2
x = a + b
# a, b now have their old values again
I knew I was ignoring nonlocals and nested function scopes. But just
trying something really simple that looks like the un-proposal in some
cases. Maybe there's no way in pure-Python to deal with the edge cases
though.
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