:mod:`sphinx.ext.napoleon` -- Support for NumPy and Google style docstrings

.. module:: sphinx.ext.napoleon :synopsis: Support for NumPy and Google style docstrings

.. moduleauthor:: Rob Ruana

.. versionadded:: 1.3

.. role:: code-py(code) :language: Python

Overview

Are you tired of writing docstrings that look like this:

.. code-block:: rst

:param path: The path of the file to wrap
:type path: str
:param field_storage: The :class:`FileStorage` instance to wrap
:type field_storage: FileStorage
:param temporary: Whether or not to delete the file when the File
   instance is destructed
:type temporary: bool
:returns: A buffered writable file descriptor
:rtype: BufferedFileStorage

reStructuredText_ is great, but it creates visually dense, hard to read :pep:docstrings <287>. Compare the jumble above to the same thing rewritten according to the Google Python Style Guide_:

.. code-block:: text

Args:
    path (str): The path of the file to wrap
    field_storage (FileStorage): The :class:`FileStorage` instance to wrap
    temporary (bool): Whether or not to delete the file when the File
       instance is destructed

Returns:
    BufferedFileStorage: A buffered writable file descriptor

Much more legible, no?

Napoleon is a :term:extension that enables Sphinx to parse both NumPy_ and Google_ style docstrings - the style recommended by Khan Academy_.

Napoleon is a pre-processor that parses NumPy_ and Google_ style docstrings and converts them to reStructuredText before Sphinx attempts to parse them. This happens in an intermediate step while Sphinx is processing the documentation, so it doesn't modify any of the docstrings in your actual source code files.

.. _ReStructuredText: https://docutils.sourceforge.io/rst.html .. _Google Python Style Guide: https://google.github.io/styleguide/pyguide.html .. _Google: https://google.github.io/styleguide/pyguide.html#38-comments-and-docstrings .. _NumPy: https://numpydoc.readthedocs.io/en/latest/format.html#docstring-standard .. _Khan Academy: https://github.com/Khan/style-guides/blob/master/style/python.md#docstrings

Getting Started


1. After :doc:`setting up Sphinx </usage/quickstart>` to build your docs,
   enable napoleon in the Sphinx ``conf.py`` file:

   .. code-block:: python

       # conf.py

       # Add napoleon to the extensions list
       extensions = ['sphinx.ext.napoleon']

2. Use ``sphinx-apidoc`` to build your API documentation:

   .. code-block:: console

       $ sphinx-apidoc -f -o docs/source projectdir


Docstrings
~~~~~~~~~~

Napoleon interprets every docstring that :mod:`autodoc <sphinx.ext.autodoc>`
can find, including docstrings on: ``modules``, ``classes``, ``attributes``,
``methods``, ``functions``, and ``variables``. Inside each docstring,
specially formatted `Sections`_ are parsed and converted to
reStructuredText.

All standard reStructuredText formatting still works as expected.


.. _Sections:

Docstring Sections

All of the following section headers are supported:

Args (alias of Parameters)
Arguments (alias of Parameters)
Attention
Attributes
Caution
Danger
Error
Example
Examples
Hint
Important
Keyword Args (alias of Keyword Arguments)
Keyword Arguments
Methods
Note
Notes
Other Parameters
Parameters
Return (alias of Returns)
Returns
Raise (alias of Raises)
Raises
References
See Also
Tip
Todo
Warning
Warnings (alias of Warning)
Warn (alias of Warns)
Warns
Yield (alias of Yields)
Yields

Google vs NumPy


Napoleon supports two styles of docstrings: `Google`_ and `NumPy`_. The
main difference between the two styles is that Google uses indentation to
separate sections, whereas NumPy uses underlines.

Google style:

.. code-block:: python

    def func(arg1, arg2):
        """Summary line.

        Extended description of function.

        Args:
            arg1 (int): Description of arg1
            arg2 (str): Description of arg2

        Returns:
            bool: Description of return value

        """
        return True

NumPy style:

.. code-block:: python

    def func(arg1, arg2):
        """Summary line.

        Extended description of function.

        Parameters
        ----------
        arg1 : int
            Description of arg1
        arg2 : str
            Description of arg2

        Returns
        -------
        bool
            Description of return value

        """
        return True

NumPy style tends to require more vertical space, whereas Google style
tends to use more horizontal space. Google style tends to be easier to
read for short and simple docstrings, whereas NumPy style tends be easier
to read for long and in-depth docstrings.

The choice between styles is largely aesthetic, but the two styles should
not be mixed. Choose one style for your project and be consistent with it.

.. seealso::

   For complete examples:

   * :ref:`example_google`
   * :ref:`example_numpy`


Type Annotations

:pep:484 introduced a standard way to express types in Python code. This is an alternative to expressing types directly in docstrings. One benefit of expressing types according to :pep:484 is that type checkers and IDEs can take advantage of them for static code analysis. :pep:484 was then extended by :pep:526 which introduced a similar way to annotate variables (and attributes).

Google style with type annotations:

.. code-block:: python

def func(arg1: int, arg2: str) -> bool:
    """Summary line.

    Extended description of function.

    Args:
        arg1: Description of arg1
        arg2: Description of arg2

    Returns:
        Description of return value

    """
    return True

class Class:
    """Summary line.

    Extended description of class

    Attributes:
        attr1: Description of attr1
        attr2: Description of attr2
    """

    attr1: int
    attr2: str

Google style with types in docstrings:

.. code-block:: python

def func(arg1, arg2):
    """Summary line.

    Extended description of function.

    Args:
        arg1 (int): Description of arg1
        arg2 (str): Description of arg2

    Returns:
        bool: Description of return value

    """
    return True

class Class:
    """Summary line.

    Extended description of class

    Attributes:
        attr1 (int): Description of attr1
        attr2 (str): Description of attr2
    """

Configuration

Listed below are all the settings used by napoleon and their default values. These settings can be changed in the Sphinx conf.py file. Make sure that "sphinx.ext.napoleon" is enabled in conf.py:

.. code-block:: python

# conf.py

# Add any Sphinx extension module names here, as strings
extensions = ['sphinx.ext.napoleon']

# Napoleon settings
napoleon_google_docstring = True
napoleon_numpy_docstring = True
napoleon_include_init_with_doc = False
napoleon_include_private_with_doc = False
napoleon_include_special_with_doc = True
napoleon_use_admonition_for_examples = False
napoleon_use_admonition_for_notes = False
napoleon_use_admonition_for_references = False
napoleon_use_ivar = False
napoleon_use_param = True
napoleon_use_rtype = True
napoleon_preprocess_types = False
napoleon_type_aliases = None
napoleon_attr_annotations = True

.. _Google style: https://google.github.io/styleguide/pyguide.html#38-comments-and-docstrings .. _NumPy style: https://numpydoc.readthedocs.io/en/latest/format.html#docstring-standard

.. confval:: napoleon_google_docstring :type: :code-py:bool :default: :code-py:True

True to parse Google style_ docstrings. False to disable support for Google style docstrings.

.. confval:: napoleon_numpy_docstring :type: :code-py:bool :default: :code-py:True

True to parse NumPy style_ docstrings. False to disable support for NumPy style docstrings.

.. confval:: napoleon_include_init_with_doc :type: :code-py:bool :default: :code-py:False

True to list __init___ docstrings separately from the class docstring. False to fall back to Sphinx's default behavior, which considers the __init___ docstring as part of the class documentation.

If True:

.. code-block:: python

   def __init__(self):
       """
       This will be included in the docs because it has a docstring
       """

   def __init__(self):
       # This will NOT be included in the docs

.. confval:: napoleon_include_private_with_doc :type: :code-py:bool :default: :code-py:False

True to include private members (like _membername) with docstrings in the documentation. False to fall back to Sphinx's default behavior.

If True:

.. code-block:: python

   def _included(self):
       """
       This will be included in the docs because it has a docstring
       """
       pass

   def _skipped(self):
       # This will NOT be included in the docs
       pass

.. confval:: napoleon_include_special_with_doc :type: :code-py:bool :default: :code-py:True

True to include special members (like __membername__) with docstrings in the documentation. False to fall back to Sphinx's default behavior.

If True:

.. code-block:: python

   def __str__(self):
       """
       This will be included in the docs because it has a docstring
       """
       return unicode(self).encode('utf-8')

   def __unicode__(self):
       # This will NOT be included in the docs
       return unicode(self.__class__.__name__)

.. confval:: napoleon_use_admonition_for_examples :type: :code-py:bool :default: :code-py:False

True to use the .. admonition:: directive for the Example and Examples sections. False to use the .. rubric:: directive instead. One may look better than the other depending on what HTML theme is used.

This NumPy style_ snippet will be converted as follows:

.. code-block:: text

   Example
   -------
   This is just a quick example

If True:

.. code-block:: rst

   .. admonition:: Example

      This is just a quick example

If False:

.. code-block:: rst

   .. rubric:: Example

   This is just a quick example

.. confval:: napoleon_use_admonition_for_notes :type: :code-py:bool :default: :code-py:False

True to use the .. admonition:: directive for Notes sections. False to use the .. rubric:: directive instead.

.. note:: The singular Note section will always be converted to a .. note:: directive.

.. seealso::

  :confval:`napoleon_use_admonition_for_examples`

.. confval:: napoleon_use_admonition_for_references :type: :code-py:bool :default: :code-py:False

True to use the .. admonition:: directive for References sections. False to use the .. rubric:: directive instead.

.. seealso::

  :confval:`napoleon_use_admonition_for_examples`

.. confval:: napoleon_use_ivar :type: :code-py:bool :default: :code-py:False

True to use the :ivar: role for instance variables. False to use the .. attribute:: directive instead.

This NumPy style_ snippet will be converted as follows:

.. code-block:: text

   Attributes
   ----------
   attr1 : int
       Description of `attr1`

If True:

.. code-block:: rst

   :ivar attr1: Description of `attr1`
   :vartype attr1: int

If False:

.. code-block:: rst

   .. attribute:: attr1

      Description of `attr1`

      :type: int

.. confval:: napoleon_use_param :type: :code-py:bool :default: :code-py:True

True to use a :param: role for each function parameter. False to use a single :parameters: role for all the parameters.

This NumPy style_ snippet will be converted as follows:

.. code-block:: text

   Parameters
   ----------
   arg1 : str
       Description of `arg1`
   arg2 : int, optional
       Description of `arg2`, defaults to 0

If True:

.. code-block:: rst

   :param arg1: Description of `arg1`
   :type arg1: str
   :param arg2: Description of `arg2`, defaults to 0
   :type arg2: :class:`int`, *optional*

If False:

.. code-block:: rst

   :parameters: * **arg1** (*str*) --
                  Description of `arg1`
                * **arg2** (*int, optional*) --
                  Description of `arg2`, defaults to 0

.. confval:: napoleon_use_keyword :type: :code-py:bool :default: :code-py:True

True to use a :keyword: role for each function keyword argument. False to use a single :keyword arguments: role for all the keywords.

This behaves similarly to :confval:napoleon_use_param. Note unlike docutils, :keyword: and :param: will not be treated the same way - there will be a separate "Keyword Arguments" section, rendered in the same fashion as "Parameters" section (type links created if possible)

.. seealso::

  :confval:`napoleon_use_param`

.. confval:: napoleon_use_rtype :type: :code-py:bool :default: :code-py:True

True to use the :rtype: role for the return type. False to output the return type inline with the description.

This NumPy style_ snippet will be converted as follows:

.. code-block:: text

   Returns
   -------
   bool
       True if successful, False otherwise

If True:

.. code-block:: rst

   :returns: True if successful, False otherwise
   :rtype: bool

If False:

.. code-block:: rst

   :returns: *bool* -- True if successful, False otherwise

.. confval:: napoleon_preprocess_types :type: :code-py:bool :default: :code-py:False

True to convert the type definitions in the docstrings as references.

.. versionadded:: 3.2.1 .. versionchanged:: 3.5

  Do preprocess the Google style docstrings also.

.. confval:: napoleon_type_aliases :type: :code-py:dict[str, str] | None :default: :code-py:None

A mapping to translate type names to other names or references. Works only when napoleon_use_param = True.

With:

.. code-block:: python

   napoleon_type_aliases = {
       "CustomType": "mypackage.CustomType",
       "dict-like": ":term:`dict-like <mapping>`",
   }

This NumPy style_ snippet:

.. code-block:: text

   Parameters
   ----------
   arg1 : CustomType
       Description of `arg1`
   arg2 : dict-like
       Description of `arg2`

becomes:

.. code-block:: rst

   :param arg1: Description of `arg1`
   :type arg1: mypackage.CustomType
   :param arg2: Description of `arg2`
   :type arg2: :term:`dict-like <mapping>`

.. versionadded:: 3.2

.. confval:: napoleon_attr_annotations :type: :code-py:bool :default: :code-py:True

True to allow using :pep:526 attributes annotations in classes. If an attribute is documented in the docstring without a type and has an annotation in the class body, that type is used.

.. versionadded:: 3.4

.. confval:: napoleon_custom_sections :type: :code-py:Sequence[str | tuple[str, str]] | None :default: :code-py:None

Add a list of custom sections to include, expanding the list of parsed sections.

The entries can either be strings or tuples, depending on the intention:

To create a custom "generic" section, just pass a string.
To create an alias for an existing section, pass a tuple containing the alias name and the original, in that order.
To create a custom section that displays like the parameters or returns section, pass a tuple containing the custom section name and a string value, "params_style" or "returns_style".

If an entry is just a string, it is interpreted as a header for a generic section. If the entry is a tuple/list/indexed container, the first entry is the name of the section, the second is the section key to emulate. If the second entry value is "params_style" or "returns_style", the custom section will be displayed like the parameters section or returns section.

.. versionadded:: 1.8 .. versionchanged:: 3.5 Support params_style and returns_style

:mod:`sphinx.ext.napoleon` -- Support for NumPy and Google style docstrings

:mod:sphinx.ext.napoleon -- Support for NumPy and Google style docstrings

Overview

Configuration

:mod:`sphinx.ext.napoleon` -- Support for NumPy and Google style docstrings