Setting up the documentation sources

The root directory of a Sphinx collection of reStructuredText 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. Just run

$ sphinx-quickstart

and answer its questions. (Be sure to say yes to the “autodoc” extension.)

There is also an automatic “API documentation” generator called sphinx-apidoc; see Invocation of sphinx-apidoc for details.

Defining document structure

Let’s assume you’ve run sphinx-quickstart. It created a source directory with conf.py and a master document, index.rst (if you accepted the defaults). The main function of the master 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 this:

.. toctree::
   :maxdepth: 2

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

.. toctree::
   :maxdepth: 2

   intro
   tutorial
   ...

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 slashes as directory separators.

Read more about the toctree directive.

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.

See reStructuredText Primer for a more in-depth introduction to reStructuredText and Sphinx Markup Constructs for a full list of markup added by Sphinx.

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, called like this:

$ sphinx-build -b html sourcedir builddir

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

See Invocation of sphinx-build for all options that sphinx-build supports.

However, sphinx-quickstart script creates a Makefile and a make.bat which make life even easier for you: with them you only need to run

$ make html

to 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’ 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. To e.g. document the Python 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.

See Sphinx Domains for all the available domains and their directives/roles.

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 your 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. If you use non-ASCII characters in any string value, you need to use Python Unicode strings (like project = u'Exposé').

See The build configuration file for documentation of all available config values.

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”.

In order to use autodoc, you need to activate it in conf.py by putting the string 'sphinx.ext.autodoc' into the list assigned to the extensions config value. Then, you have a few additional directives at your disposal.

For example, to document the function io.open(), reading its signature and docstring from the source file, you’d write this:

.. autofunction:: io.open

You can also document whole classes or even modules automatically, using member options for the auto directives, like

.. automodule:: io
   :members:

autodoc needs to import your modules in order to extract the docstrings. Therefore, you must add the appropriate path to sys.path in your conf.py.

See sphinx.ext.autodoc for the complete description of the features of autodoc.

More topics to be covered

• Other extensions (math, intersphinx, viewcode, doctest)
• Static files
• Selecting a theme
• Templating
• Using extensions
• Writing extensions

Footnotes