On Fri, Nov 8, 2019 at 11:07 AM Ricky Teachey <ri...@teachey.org> wrote:
>
>
>> __import__ already has a 'level' argument.
>>
>
> doh! maybe "context" is better, then.
>
>
>> Not without frame inspection to know what import statements are in the
>> context manager's block.
>>
>>
> I don't doubt you know what you're talking about, so this is a learning
> question: why couldn't you do it by simply adding an
> "inside_context_manager" flag, and producing an appropriate globals and
> locals based on the flag value?
>
Not thread-safe (we have a custom import lock to avoid this sort of
problem) and the instant you start mucking with globals() and locals() you
have (a) become a bit magical, and (b) made things extremely slow for PyPy.
My opinion on this idea is while I appreciate the motivation behind it,
this is proposing a lot of churn and change in Python to fix a single issue
that only some people hit and most people learn to avoid the first time to
realize what they have done. If it was a problem people ran into constantly
throughout their life using Python then maybe I would personally be more
receptive, but since it's a one-time mistake for vast majority of people I
think I don't feel comfortable making every book on Python be outdated
overnight over this.
-Brett
>
> this is really lame, but maybe like this:
>
> class __import__:
>
> def __enter__(self):
> self.inside_context_manager = True
> return None
>
> def __exit__(self, *args):
> self.inside_context_manager = False
>
> def __call__(self, name, globals=None, locals=None, fromlist=(),
> level=0, context=None):
> am_i_outside_context_manager = not self.inside_context_manager
> if am_i_outside_context_manager:
> do_normal_import(name, globals, locals, fromlist, level)
> else:
> # inside context manager
> if context is None:
> raise ValueError("invalid import context")
> cglobals = contextualized_globals(globals, context)
> clocals = contextualized_locals(locals, context)
> do_special_import(name, cglobals, clocals, fromlist, level)
>
>
>
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