.. program:: stubgen

A stub file (see PEP 484) contains only type hints for the public interface of a module, with empty function bodies. Mypy can use a stub file instead of the real implementation to provide type information for the module. They are useful for third-party modules whose authors have not yet added type hints (and when no stubs are available in typeshed) and C extension modules (which mypy can't directly process).

Mypy includes the stubgen tool that can automatically generate stub files (.pyi files) for Python modules and C extension modules. For example, consider this source file:

from other_module import dynamic

BORDER_WIDTH = 15

class Window:
    parent = dynamic()
    def __init__(self, width, height):
        self.width = width
        self.height = height

def create_empty() -> Window:
    return Window(0, 0)

Stubgen can generate this stub file based on the above file:

from typing import Any

BORDER_WIDTH: int = ...

class Window:
    parent: Any = ...
    width: Any = ...
    height: Any = ...
    def __init__(self, width, height) -> None: ...

def create_empty() -> Window: ...

Stubgen generates draft stubs. The auto-generated stub files often require some manual updates, and most types will default to Any. The stubs will be much more useful if you add more precise type annotations, at least for the most commonly used functionality.

The rest of this section documents the command line interface of stubgen. Run stubgen --help for a quick summary of options.

You can give stubgen paths of the source files for which you want to generate stubs:

$ stubgen foo.py bar.py

This generates stubs out/foo.pyi and out/bar.pyi. The default output directory out can be overridden with :option:`-o DIR <-o>`.

You can also pass directories, and stubgen will recursively search them for any .py files and generate stubs for all of them:

$ stubgen my_pkg_dir

Alternatively, you can give module or package names using the -m or -p options:

$ stubgen -m foo -m bar -p my_pkg_dir

Details of the options:

.. option:: -m MODULE, --module MODULE

    Generate a stub file for the given module. This flag may be repeated
    multiple times.

    Stubgen *will not* recursively generate stubs for any submodules of
    the provided module.

.. option:: -p PACKAGE, --package PACKAGE

    Generate stubs for the given package. This flag maybe repeated
    multiple times.

    Stubgen *will* recursively generate stubs for all submodules of
    the provided package. This flag is identical to :option:`--module` apart from
    this behavior.

By default stubgen will try to import the target modules and packages. This allows stubgen to use runtime introspection to generate stubs for C extension modules and to improve the quality of the generated stubs. By default, stubgen will also use mypy to perform light-weight semantic analysis of any Python modules. Use the following flags to alter the default behavior:

.. option:: --no-import

    Don't try to import modules. Instead use mypy's normal search mechanism to find
    sources. This does not support C extension modules. This flag also disables
    runtime introspection functionality, which mypy uses to find the value of
    ``__all__``. As result the set of exported imported names in stubs may be
    incomplete. This flag is generally only useful when importing a module generates
    an error for some reason.

.. option:: --parse-only

    Don't perform semantic analysis of source files. This may generate
    worse stubs -- in particular, some module, class, and function aliases may
    be represented as variables with the ``Any`` type. This is generally only
    useful if semantic analysis causes a critical mypy error.

.. option:: --doc-dir PATH

    Try to infer better signatures by parsing .rst documentation in ``PATH``.
    This may result in better stubs, but currently it only works for C extension
    modules.

.. option:: --py2

    Run stubgen in Python 2 mode (the default is Python 3 mode).

.. option:: --ignore-errors

    If an exception was raised during stub generation, continue to process any
    remaining modules instead of immediately failing with an error.

.. option:: --include-private

    Include definitions that are considered private in stubs (with names such
    as ``_foo`` with single leading underscore and no trailing underscores).

.. option:: --search-path PATH

    Specify module search directories, separated by colons (only used if
    :option:`--no-import` is given).

.. option:: --python-executable PATH

    Use Python interpreter at ``PATH`` for importing modules and runtime
    introspection. This has no effect with :option:`--no-import`, and this only works
    in Python 2 mode. In Python 3 mode the Python interpreter used to run stubgen
    will always be used.

.. option:: -o PATH, --output PATH

    Change the output directory. By default the stubs are written in the
    ``./out`` directory. The output directory will be created if it doesn't
    exist. Existing stubs in the output directory will be overwritten without
    warning.