.. _autodoc_ext_tutorial:

Developing autodoc extensions

The objective of this tutorial is to create an extension that adds support for new type for autodoc. This autodoc extension will format the IntEnum class from Python standard library. (module enum)

Overview

We want the extension that will create auto-documentation for IntEnum. IntEnum is the integer enum class from standard library enum module.

Currently this class has no special auto documentation behavior.

We want to add following to autodoc:

A new autointenum directive that will document the IntEnum class.
The generated documentation will have all the enum possible values with names.
The autointenum directive will have an option :hex: which will cause the integers be printed in hexadecimal form.

Prerequisites

We need the same setup as in :ref:the previous extensions <tutorial-extend-build>. This time, we will be putting out extension in a file called :file:autodoc_intenum.py. The :file:my_enums.py will contain the sample enums we will document.

Here is an example of the folder structure you might obtain:

.. code-block:: text

  └── source
      ├── _ext
      │   └── autodoc_intenum.py
      ├── conf.py
      ├── index.rst
      └── my_enums.py

Writing the extension

Start with setup function for the extension.

.. literalinclude:: examples/autodoc_intenum.py :language: python :linenos: :pyobject: setup

The :meth:~sphinx.application.Sphinx.setup_extension method will pull the autodoc extension because our new extension depends on autodoc. :meth:~sphinx.application.Sphinx.add_autodocumenter is the method that registers our new auto documenter class.

We want to import certain objects from the autodoc extension:

.. literalinclude:: examples/autodoc_intenum.py :language: python :linenos: :lines: 1-7

There are several different documenter classes such as MethodDocumenter or AttributeDocumenter available in the autodoc extension but our new class is the subclass of ClassDocumenter which a documenter class used by autodoc to document classes.

This is the definition of our new the auto-documenter class:

.. literalinclude:: examples/autodoc_intenum.py :language: python :linenos: :pyobject: IntEnumDocumenter

Important attributes of the new class:

objtype This attribute determines the auto directive name. In this case the auto directive will be autointenum.

directivetype This attribute sets the generated directive name. In this example the generated directive will be .. :py:class::.

priority the larger the number the higher is the priority. We want our documenter be higher priority than the parent.

option_spec option specifications. We copy the parent class options and add a new option hex.

Overridden members:

can_document_member This member is important to override. It should return True when the passed object can be documented by this class.

add_directive_header This method generates the directive header. We add :final: directive option. Remember to call super or no directive will be generated.

add_content This method generates the body of the class documentation. After calling the super method we generate lines for enum description.

Using the extension

You can now use the new autodoc directive to document any IntEnum.

For example, you have the following IntEnum:

.. code-block:: python :caption: my_enums.py

class Colors(IntEnum): """Colors enumerator""" NONE = 0 RED = 1 GREEN = 2 BLUE = 3

This will be the documentation file with auto-documentation directive:

.. code-block:: rst :caption: index.rst

.. autointenum:: my_enums.Colors

Developing autodoc extensions

Developing autodoc extensions

Overview

Prerequisites

Writing the extension

Using the extension

Further reading