Type annotations don't work in strict mode with mypy

[gaborbernat]

Python 3.9.5 + mypy 0.812

# magic.py
from jinja2 import Environment

mypy ./magic.py
Success: no issues found in 1 source file

mypy ./magic.py --strict
magic.py:1: error: Module 'jinja2' does not explicitly export attribute 'Environment'; implicit reexport disabled
Found 1 error in 1 file (checked 1 source file)

Thanks 👍

[davidism]

You can add the following config to your project to allow Jinja (or other packages) to export from __init__, since it's a very common pattern.

[mypy-jinja2]
no_implicit_reexport = False

See python/mypy#10198 for discussion on changing this behavior.

[gaborbernat]

I'd expect that configuration to be part of the upstream project, not the downstream user. Seems it's a choice of the project if they want implicit re-export or not, not the user apps 🤔 All other projects I've been using until now used explicit exports to work around this.

[davidism]

There is no configuration that upstream projects can provide.

[gaborbernat]

Hence why most projects use explicit export to not run into this. If you insist on implicit re-export feels like worth creating a PEP and allowing this configurability.

[dquitmann-op]

Hi @davidism,

is there any release schedule for 3.0.1 fixing this behavior? I do not want to build any pressure, just to know if we should (temporarily) change our pipelines or just can wait for a fixed release coming in the next days.

Thanks very much for the quick fix and your answer in advance!