Exclude multiple directories on mypy commandline: improve documentation

[cclauss]

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This question is about the mypy commandline, not about mypy configuration files.

The --exclude documentation does not explain how to exclude multiple directories on mypy commandline.

Should there be a single --exclude option with comma-separated terms or
should there be multiple --exclude options whose terms would be additive?

mypy --ignore-missing-imports --exclude @mypy_failing_files.txt # does not work as expected.

Given https://github.com/TheAlgorithms/Python we would like to exclude directories until they can be made mypy compatible. We currently have an include list that works but as our mypy compatibility increases, we would like to switch to a shorter exclude list like:

 mypy --ignore-missing-imports \
           --exclude ./arithmetic_analysis/ \
           --exclude ./ciphers/ \
           --exclude ./compression/ \
           --exclude ./conversions/ \
           --exclude ./data_structures/ \
           --exclude ./digital_image_processing/ \
           --exclude ./dynamic_programming/ \
           --exclude ./graphics/ \
           --exclude ./graphs/ \
           --exclude ./hashes/ \
           --exclude ./linear_algebra/ \
           --exclude ./maths/ \
           --exclude ./matrix/ \
           --exclude ./other/ \
           --exclude ./project_euler/ \
           --exclude ./scripts/ \
           --exclude ./searches/ \
           --exclude ./strings/ \
           --exclude ./web_programming/ .

[cclauss]

This works... Closing.

mypy --ignore-missing-imports \
    --exclude '(arithmetic_analysis|ciphers|compression|conversions|data_structures|digital_image_processing|dynamic_programming|graphics|graphs|hashes|linear_algebra|maths|matrix|other|project_euler|scripts|searches|strings|web_programming*)/$' .

[JelleZijlstra]

If the correct solution isn't obvious, the documentation should be improved. We could add an example excluding multiple directories.

[sam-hoffman]

I also found that the correct syntax wasn't obvious :( would really appreciate an example excluding multiple directories and an example excluding from a config file

[JelleZijlstra]

Reopening as a docs issue

[hauntsaninja]

The docs (that you linked to) do technically have an example excluding multiple things: --exclude '/(site-packages|node_modules|__pycache__|\..*)/$'

[cclauss]

That example has \..*)/$ which makes it difficult to understand for people who are not regex gurus.

If I want to land mypy in the continuous integration of a project but there are ten files or directories that are not yet compliant, how can I write a --exclude that spreads out over multiple lines so it more readable than #10250 (comment) ?

[JukkaL]

It could be good to have a few more examples in the docs, each of which only does a fairly specific thing, and clearly explain what each example does exactly. Regular expressions are not very familiar to everybody, and they can be used in subtly incorrect ways that result in false negatives or other unexpected results.

[stevekm]

I consider myself to be pretty decent with regex and even I cannot figure out how to simultaneously exclude

• files in some subdir matching a pattern (e.g. my Django migration files)
• a couple specific files scattered throughout the repo

Being forced to write one massive regex for this is pretty horrible. The command line syntax should be more similar to find and rsync which both allow for multiple inclusion and exclusion criteria in a more sensible way.