sphinx-autodoc-future-annotations 0.1.3

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This extension allows you to use Python 3 type annotations for documenting module and class attributes and function arguments and return types. The extension also has support for cyclic imports needed due to type annotations. The extension only works for Python 3.7 and higher and requires the use of from __future__ import annotations.

Example (a_module.py):

from __future__ import annotations

import typing as t

if t.TYPE_CHECKING:
    import another_module

module_attribute: t.Optional[another_module.SomeClass] = None
'''An attribute of the module.'''

class AClass:
    '''A class.'''

    instance_attribute: int
    '''An instance attribute.'''

    class_attribute: float = 3.0
    '''A class attribute.'''

    def __init__(self, arg: t.Union[int, str]):
        pass

    def method(self) -> int:
        '''A method.'''
        pass

Example (another_module.py):

from __future__ import annotations

import typing

if typing.TYPE_CHECKING:
    import a_module

def function(arg: a_module.AClass):
    '''A function.'''
    pass

class SomeClass:
    pass

Installation and setup

First, use pip to download and install the extension:

$ pip install sphinx_autodoc_future_annotations

Then, add the extension to your conf.py:

extensions = [
    'sphinx.ext.autodoc',
    'sphinx_autodoc_future_annotations',
]

How it works

Cyclic imports needed due to type annotations are supported in the following way. First, a hook is monkey-patched into sphinx.ext.autodoc to act when a module is imported. This hook first imports the module normally. Then it parses the module’s code and finds any top-level if-statements that are conditional on TYPE_CHECKING from the typing module. All statements inside such if-statements are executed in the context of te module. This makes the additional imports available to typing.get_type_hints.

The extension listens to the autodoc-process-signature and autodoc-process-docstring Sphinx events. In the former, it strips the annotations from the function signature. In the latter, it injects the appropriate :type argname: and :rtype: directives into the docstring.

The :type argname: and :rtype: directives are added if and only if no existing matching directive is found. Empty :param argname: directives are added if no matching directive is found. This allows to document the type of an argument without having to add trivial documentation on its use.

This extension does not currently have any configuration options.

Some of the code is adapted from sphinx-autodoc-typehints.

Compatibility with sphinx.ext.napoleon

To use sphinx.ext.napoleon with sphinx_autodoc_future_annotations, make sure you load sphinx.ext.napoleon first, before sphinx_autodoc_future_annotations.

extensions = [
    'sphinx.ext.autodoc',
    'sphinx.ext.napoleon',
    'sphinx_autodoc_future_annotations',
]