How to automatically generate Python .pyi stub files from existing .py source files

Question

How to make stub .pyi file automatically from an existing .py source file?

Answer

Use stubgen, which is included with mypy, to automatically generate draft .pyi files from existing Python source files.

Note: The generated .pyi file should be reviewed manually. Automatically generated stubs may contain incomplete types or Any where the tool cannot infer accurate type information.

1. Install mypy

Run the following command:

python -m pip install mypy

2. Generate a Stub File from a Single Python File

Use the following command:

stubgen path/to/example.py -o stubs

Example:

stubgen calculator.py -o stubs

Expected output:

stubs/calculator.pyi

3. Generate Stubs for Multiple Python Files

stubgen foo.py bar.py -o stubs

This generates:

stubs/foo.pyi
stubs/bar.pyi

Alternatively, installing the module via pip install . allows PyCharm to generate skeletons automatically, which eliminates the need for maintaining a stub file.

For further context, note that this behavior is a known limitation of PyCharm. You can track its progression or vote for its prioritization here: Build skeletons for binary modules under project content.