Setting up the documentation sources¶

The root directory of a Sphinx collection of plain-text document sources is called the source directory. This directory also contains the Sphinx configuration file conf.py, where you can configure all aspects of how Sphinx reads your sources and builds your documentation. [1]

Sphinx comes with a script called sphinx-quickstart that sets up a source directory and creates a default conf.py with the most useful configuration values from a few questions it asks you. To use this, run:

$ sphinx-quickstart

Defining document structure¶

Let’s assume you’ve run sphinx-quickstart. It created a source directory with conf.py and a root document, index.rst. The main function of the root document is to serve as a welcome page, and to contain the root of the “table of contents tree” (or toctree). This is one of the main things that Sphinx adds to reStructuredText, a way to connect multiple files to a single hierarchy of documents.

The toctree directive initially is empty, and looks like so:

.. toctree::
   :maxdepth: 2

You add documents listing them in the content of the directive:

.. toctree::
   :maxdepth: 2

   usage/installation
   usage/quickstart
   ...

This is exactly how the toctree for this documentation looks. The documents to include are given as document names, which in short means that you leave off the file name extension and use forward slashes (/) as directory separators.

You can now create the files you listed in the toctree and add content, and their section titles will be inserted (up to the maxdepth level) at the place where the toctree directive is placed. Also, Sphinx now knows about the order and hierarchy of your documents. (They may contain toctree directives themselves, which means you can create deeply nested hierarchies if necessary.)

Adding content¶

In Sphinx source files, you can use most features of standard reStructuredText. There are also several features added by Sphinx. For example, you can add cross-file references in a portable way (which works for all output types) using the ref role.

For an example, if you are viewing the HTML version, you can look at the source for this document – use the “Show Source” link in the sidebar.

Running the build¶

Now that you have added some files and content, let’s make a first build of the docs. A build is started with the sphinx-build program:

$ sphinx-build -M html sourcedir outputdir

where sourcedir is the source directory, and outputdir is the directory in which you want to place the built documentation. The -M option selects a builder; in this example Sphinx will build HTML files.

You can also build a live version of the documentation that you can preview in the browser. It will detect changes and reload the page any time you make edits. To do so, use sphinx-autobuild to run the following command:

$ sphinx-autobuild source-dir output-dir

However, sphinx-quickstart script creates a Makefile and a make.bat which make life even easier for you. These can be executed by running make with the name of the builder. For example.

$ make html

This will build HTML docs in the build directory you chose. Execute make without an argument to see which targets are available.

Documenting objects¶

One of Sphinx’s main objectives is easy documentation of objects (in a very general sense) in any domain. A domain is a collection of object types that belong together, complete with markup to create and reference descriptions of these objects.

The most prominent domain is the Python domain. For example, to document Python’s built-in function enumerate(), you would add this to one of your source files.

.. py:function:: enumerate(sequence[, start=0])

   Return an iterator that yields tuples of an index and an item of the
   *sequence*. (And so on.)

This is rendered like this:

enumerate(sequence[, start=0])¶

Return an iterator that yields tuples of an index and an item of the sequence. (And so on.)

The argument of the directive is the signature of the object you describe, the content is the documentation for it. Multiple signatures can be given, each in its own line.

The Python domain also happens to be the default domain, so you don’t need to prefix the markup with the domain name.

.. function:: enumerate(sequence[, start=0])

   ...

does the same job if you keep the default setting for the default domain.

There are several more directives for documenting other types of Python objects, for example py:class or py:method. There is also a cross-referencing role for each of these object types. This markup will create a link to the documentation of enumerate().

The :py:func:`enumerate` function can be used for ...

And here is the proof: A link to enumerate().

Again, the py: can be left out if the Python domain is the default one. It doesn’t matter which file contains the actual documentation for enumerate(); Sphinx will find it and create a link to it.

Each domain will have special rules for how the signatures can look like, and make the formatted output look pretty, or add specific features like links to parameter types, e.g. in the C/C++ domains.

Basic configuration¶

Earlier we mentioned that the conf.py file controls how Sphinx processes your documents. In that file, which is executed as a Python source file, you assign configuration values. For advanced users: since it is executed by Sphinx, you can do non-trivial tasks in it, like extending sys.path or importing a module to find out the version you are documenting.

The config values that you probably want to change are already put into the conf.py by sphinx-quickstart and initially commented out (with standard Python syntax: a # comments the rest of the line). To change the default value, remove the hash sign and modify the value. To customize a config value that is not automatically added by sphinx-quickstart, just add an additional assignment.

Keep in mind that the file uses Python syntax for strings, numbers, lists and so on. The file is saved in UTF-8 by default, as indicated by the encoding declaration in the first line.

Autodoc¶

When documenting Python code, it is common to put a lot of documentation in the source files, in documentation strings. Sphinx supports the inclusion of docstrings from your modules with an extension (an extension is a Python module that provides additional features for Sphinx projects) called autodoc.

Intersphinx¶

Many Sphinx documents including the Python documentation are published on the Internet. When you want to make links to such documents from your documentation, you can do it with sphinx.ext.intersphinx.

In order to use intersphinx, you need to activate it in conf.py by putting the string 'sphinx.ext.intersphinx' into the extensions list and set up the intersphinx_mapping config value.

For example, to link to io.open() in the Python library manual, you need to setup your intersphinx_mapping like:

intersphinx_mapping = {'python': ('https://docs.python.org/3', None)}

And now, you can write a cross-reference like :py:func:`io.open`. Any cross-reference that has no matching target in the current documentation set, will be looked up in the documentation sets configured in intersphinx_mapping (this needs access to the URL in order to download the list of valid targets). Intersphinx also works for some other domain's roles including :ref:, however it doesn’t work for :doc: as that is non-domain role.

More topics to be covered¶

• Other extensions:

• Static files

• Selecting a theme

• Templating

• Using extensions

• Writing extensions

Footnotes