[Python-Dev] Concurrent.futures: no type discovery for PyCharm

[Guido van Rossum]

In any case I think this should be filed (by the OP) as an issue against
JetBrains' PyCharm issue tracker. Who knows they may be able to
special-case this in a jiffy. I don't think we should add any clever hacks
to the stdlib for this.

On Tue, Apr 23, 2019 at 9:59 AM Nathaniel Smith <njs at pobox.com> wrote:

> On Tue, Apr 23, 2019, 05:09 Andrew Svetlov <andrew.svetlov at gmail.com>
> wrote:
>
>> I agree that `from typing import TYPE_CHECKING` is not desirable from
>> the import time reduction perspective.
>>
>> From my understanding code completion *can* be based on type hinting
>> to avoid actual code execution.
>> That's why I've mentioned that typeshed already has the correct type
>> information.
>>
>> if TYPE_CHECKING:
>>     import ...
>>
>> requires mypy modification.
>>
>> if False:
>>     import ...
>>
>> Works right now for stdlib (mypy ignores stdlib code but uses typeshed
>> anyway) but looks a little cryptic.
>> Requires a comprehensive comment at least.
>>
>
> Last time I looked at this, I'm pretty sure `if False` broke at least one
> popular static analysis tool (ie it was clever enough to ignore everything
> inside `if False`) – I think either pylint or jedi?
>
> I'd suggest checking any clever hacks against at least: mypy,
> pylint/astroid, jedi, pyflakes, and pycharm. They all have their own static
> analysis engines, and each one has its own idiosyncratic quirks.
>
> We've struggled with this a *lot* in trio, and eventually ended up giving
> up on all forms of dynamic export cleverness; we've even banned the use of
> __all__ entirely. Static analysis has gotten good enough that users won't
> accept it not working, but it hasn't gotten good enough to handle anything
> but the simplest static exports in a reliable way:
>     https://github.com/python-trio/trio/pull/316
>     https://github.com/python-trio/trio/issues/542
>
> The stdlib has more leeway because when tools don't work on the stdlib
> then they tend to eventually add workarounds. I'm just saying, think twice
> before diving into clever hacks to workaround static analysis limits, and
> if you're going to do it then be careful to be thorough. You're basically
> relying on undocumented bugs, and it gets really messy really quickly.
>
> -n
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-- 
--Guido van Rossum (python.org/~guido)
*Pronouns: he/him/his **(why is my pronoun here?)*
<http://feministing.com/2015/02/03/how-using-they-as-a-singular-pronoun-can-change-the-world/>
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