On 2019-11-08 18:09, Brett Cannon wrote:
On Fri, Nov 8, 2019 at 10:01 AM Ricky Teachey <ri...@teachey.org
<mailto:ri...@teachey.org>> wrote:
throwing this idea out there, no idea if it is practical but it
might be pretty nice/easily understood syntax.
could a context manager be created such that anything imported under
it is guaranteed to be imported from the standard library, and
produce an error otherwise? perhaps by adding a level keyword
argument to the __import__ built in.
__import__ already has a 'level' argument.
something like:
with __import__(level="std"):
# imports guaranteed to fail of not in the standard library
from pathlib import Path
from sys import argv
with __import__(level="package"):
# imports guaranteed to fail of not in the current package
import mod1
import mod2
with __import__(level="local"):
# imports guaranteed to fail of not in the local directory
import mod1
import mod2
with __import__(level="site"):
# imports guaranteed to fail if not in site-packages, or some
other definition that makes sense
import numpy as np
Not without frame inspection to know what import statements are in the
context manager's block.
This can all be done with code which calls importlib.import_module() and
checks __spec__.origin to see where the module came from. Basically if
you're willing to give up the syntax support of 'import' statements
(which are just calls to __import__ with some assignments afterwards to
bind things to names) you can have this protection today without adding
syntax (which is always a massive ask).
If we were to add syntax, the best I think I can come up with is:
# imports guaranteed to fail of not in the standard library
from pathlib in std import Path
from sys in std import argv
# imports guaranteed to fail of not in the current package
import mod1 in package
import mod2 in package
# imports guaranteed to fail of not in the local directory
import mod1 in local
import mod2 in local
# imports guaranteed to fail if not in site-packages, or some other
definition that makes sense
import numpy in site as np
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