Friday, 19 February 2021

Mypy 0.812 Released

We’ve just uploaded mypy 0.812 to the Python Package Index (PyPI). Mypy is a static type checker for Python. This release includes a fix to a regression in source file finding logic in mypy 0.800, and a new command-line option --exclude to exclude paths from the build. You can install it as follows:

    python3 -m pip install -U mypy

You can read the full documentation for this release on Read the Docs.

Improved Source File Finding

Mypy 0.800 changed how mypy finds modules if you run mypy as mypy directory/ or mypy -p package. Mypy started looking for source files in directories without a file. This is often the expected behavior, and it avoids excluding some files that should be type checked.

However, this caused issues for some users, such as when using mypy . to type check all files under the current directory. Mypy could now try to type check files inside nested virtual environments and node_modules directories, which is usually not desirable. This could result in mypy needlessly complaining about duplicate module names, in particular.

Now mypy will skip directories named site-packages or node_modules, and any directory beginning with a dot (such as .git) when recursively looking for files to check.

This doesn’t affect how mypy resolves imports — it only affects when mypy is given a directory or a package to type check. You can override the exclusions by explicitly passing the files on the command line.

This was contributed by Shantanu (PR 9992).

Excluding Paths

Mypy now supports the --exclude regex command line option to exclude paths matching a regular expression when searching for files to type check. For example, mypy --exclude '/setup\.py$' skips all files. This lets you exclude additional paths that mypy started finding after mypy 0.800 changed module finding behavior, as discussed above.

You can also specify this in the config file (exclude=regex). The option expects forward slashes as directory separators on all platforms, including Windows, for consistency.

This was also contributed by Shantanu (PR 9992). See the documentation for more details.

Typeshed Updates

There are no typeshed updates in this release.


Thanks to Shantanu who contributed to this release.

We’d also like to thank our employer, Dropbox, for funding the mypy core team.