On Mon, 5 Dec 2022 at 06:04, David Mertz, Ph.D. <[email protected]> wrote:
>
> Like most commenters, I think the whole "create an anonymous function then
> call it" scoping thing is too complex and has too many edge cases to be a
> good idea.
>
> That said, I decided to play around with what I can do to serve the general
> purpose within existing Python:
>
> >>> @contextmanager
> ... def local(pats=["scoped_*"]):
> ... try:
> ... yield
> ... finally:
> ... for _var in list(globals()):
> ... for pat in pats:
> ... if fnmatch(_var, pat):
> ... exec(f"del {_var}", globals())
> ...
> >>> with local(['a', 'b', 'c']):
> ... a, b = 5, 6
> ... c = a + b
> ... d = c**2
> ... print(d)
> ...
> 121
> >>> a
> Traceback (most recent call last):
> Cell In [37], line 1
> a
> NameError: name 'a' is not defined
>
> >>> d
> 121
>
You're not the first to try to use globals() for this, but it means
that the context manager works ONLY at top-level. You can't do this
with it:
def foo():
with local("abc"):
a, b = 5, 6
c = a + b
d = c ** 2
print(d)
print(a)
and expect it to work.
(Side point, though: if you're deleting a name from globals(), why not
just delete it straight out of the dictionary rather than exec'ing?)
ChrisA
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