sphinx/doc/rest.rst

.. highlightlang:: rest

reStructuredText Primer
=======================

This section is a brief introduction to reStructuredText (reST) concepts and
syntax, intended to provide authors with enough information to author documents
productively.  Since reST was designed to be a simple, unobtrusive markup
language, this will not take too long.

.. seealso::

    The authoritative `reStructuredText User
    Documentation <http://docutils.sourceforge.net/rst.html>`_.


Paragraphs
----------

The paragraph is the most basic block in a reST document.  Paragraphs are simply
chunks of text separated by one or more blank lines.  As in Python, indentation
is significant in reST, so all lines of the same paragraph must be left-aligned
to the same level of indentation.


Inline markup
-------------

The standard reST inline markup is quite simple: use

* one asterisk: ``*text*`` for emphasis (italics),
* two asterisks: ``**text**`` for strong emphasis (boldface), and
* backquotes: ````text```` for code samples.

If asterisks or backquotes appear in running text and could be confused with
inline markup delimiters, they have to be escaped with a backslash.

Be aware of some restrictions of this markup:

* it may not be nested,
* content may not start or end with whitespace: ``* text*`` is wrong,
* it must be separated from surrounding text by non-word characters.  Use a
  backslash escaped space to work around that: ``thisis\ *one*\ word``.

These restrictions may be lifted in future versions of the docutils.

reST also allows for custom "interpreted text roles"', which signify that the
enclosed text should be interpreted in a specific way.  Sphinx uses this to
provide semantic markup and cross-referencing of identifiers, as described in
the appropriate section.  The general syntax is ``:rolename:`content```.


Lists and Quotes
----------------

List markup is natural: just place an asterisk at the start of a paragraph and
indent properly.  The same goes for numbered lists; they can also be
autonumbered using a ``#`` sign::

   * This is a bulleted list.
   * It has two items, the second
     item uses two lines.

   1. This is a numbered list.
   2. It has two items too.

   #. This is a numbered list.
   #. It has two items too.


Nested lists are possible, but be aware that they must be separated from the
parent list items by blank lines::

   * this is
   * a list

     * with a nested list
     * and some subitems

   * and here the parent list continues

Definition lists are created as follows::

   term (up to a line of text)
      Definition of the term, which must be indented

      and can even consist of multiple paragraphs

   next term
      Description.


Paragraphs are quoted by just indenting them more than the surrounding
paragraphs.


Source Code
-----------

Literal code blocks are introduced by ending a paragraph with the special marker
``::``.  The literal block must be indented (and, like all paragraphs, separated
from the surrounding ones by blank lines)::

   This is a normal text paragraph. The next paragraph is a code sample::

      It is not processed in any way, except
      that the indentation is removed.

      It can span multiple lines.

   This is a normal text paragraph again.

The handling of the ``::`` marker is smart:

* If it occurs as a paragraph of its own, that paragraph is completely left
  out of the document.
* If it is preceded by whitespace, the marker is removed.
* If it is preceded by non-whitespace, the marker is replaced by a single
  colon.

That way, the second sentence in the above example's first paragraph would be
rendered as "The next paragraph is a code sample:".


Hyperlinks
----------

External links
^^^^^^^^^^^^^^

Use ```Link text <http://target>`_`` for inline web links.  If the link text
should be the web address, you don't need special markup at all, the parser
finds links and mail addresses in ordinary text.

Internal links
^^^^^^^^^^^^^^

Internal linking is done via a special reST role, see the section on specific
markup, :ref:`ref-role`.


Sections
--------

Section headers are created by underlining (and optionally overlining) the
section title with a punctuation character, at least as long as the text::

   =================
   This is a heading
   =================

Normally, there are no heading levels assigned to certain characters as the
structure is determined from the succession of headings.  However, for the
Python documentation, this convention is used which you may follow:

* ``#`` with overline, for parts
* ``*`` with overline, for chapters
* ``=``, for sections
* ``-``, for subsections
* ``^``, for subsubsections
* ``"``, for paragraphs

Of course, you are free to use your own marker characters (see the reST
documentation), and use a deeper nesting level, but keep in mind that most
target formats (HTML, LaTeX) have a limited supported nesting depth.


Explicit Markup
---------------

"Explicit markup" is used in reST for most constructs that need special
handling, such as footnotes, specially-highlighted paragraphs, comments, and
generic directives.

An explicit markup block begins with a line starting with ``..`` followed by
whitespace and is terminated by the next paragraph at the same level of
indentation.  (There needs to be a blank line between explicit markup and normal
paragraphs.  This may all sound a bit complicated, but it is intuitive enough
when you write it.)


Directives
----------

A directive is a generic block of explicit markup.  Besides roles, it is one of
the extension mechanisms of reST, and Sphinx makes heavy use of it.

Basically, a directive consists of a name, arguments, options and content. (Keep
this terminology in mind, it is used in the next chapter describing custom
directives.)  Looking at this example, ::

   .. function:: foo(x)
                 foo(y, z)
      :bar: no

      Return a line of text input from the user.

``function`` is the directive name.  It is given two arguments here, the
remainder of the first line and the second line, as well as one option ``bar``
(as you can see, options are given in the lines immediately following the
arguments and indicated by the colons).

The directive content follows after a blank line and is indented relative to the
directive start.


Images
------

reST supports an image directive, used like so::

   .. image:: gnu.png
      (options)

When used within Sphinx, the file name given (here ``gnu.png``) must be relative
to the source file, and Sphinx will automatically copy image files over to a
subdirectory of the output directory on building (e.g. the ``_static`` directory
for HTML output.)

Sphinx extends the standard docutils behavior by allowing an asterisk for the
extension::

   .. image:: gnu.*

Sphinx then searches for all images matching the provided pattern and determines
their type.  Each builder then chooses the best image out of these candidates.
For instance, if the file name ``gnu.*`` was given and two files :file:`gnu.pdf`
and :file:`gnu.png` existed in the source tree, the LaTeX builder would choose
the former, while the HTML builder would prefer the latter.

.. versionchanged:: 0.4
   Added the support for file names ending in an asterisk.


Footnotes
---------

For footnotes, use ``[#name]_`` to mark the footnote location, and add the
footnote body at the bottom of the document after a "Footnotes" rubric heading,
like so::

   Lorem ipsum [#f1]_ dolor sit amet ... [#f2]_

   .. rubric:: Footnotes

   .. [#f1] Text of the first footnote.
   .. [#f2] Text of the second footnote.

You can also explicitly number the footnotes (``[1]_``) or use auto-numbered
footnotes without names (``[#]_``).


Citations
---------

Standard reST citations are supported, with the additional feature that they are
"global", i.e. all citations can be referenced from all files.  Use them like
so::

   Lorem ipsum [Ref]_ dolor sit amet.

   .. [Ref] Book or article reference, URL or whatever.

Citation usage is similar to footnote usage, but with a label that is not
numeric or begins with ``#``.


Substitutions
-------------

reST supports "substitutions", which are pieces of text and/or markup referred
to in the text by ``|name|``.  They are defined like footnotes with explicit
markup blocks, like this::

   .. |name| replace:: replacement *text*

See the `reST reference for substitutions
<http://docutils.sourceforge.net/docs/ref/rst/restructuredtext.html#substitution-definitions>`_
for details.
   
If you want to use some substitutions for all documents, put them into a
separate file and include it into all documents you want to use them in, using
the :dir:`include` directive.  Be sure to give the include file a file name
extension differing from that of other source files, to avoid Sphinx finding it
as a standalone document.

Sphinx defines some default substitutions, see :ref:`default-substitutions`.


Comments
--------

Every explicit markup block which isn't a valid markup construct (like the
footnotes above) is regarded as a comment.  For example::

   .. This is a comment.

You can indent text after a comment start to form multiline comments::
   
   ..
      This whole indented block
      is a comment.

      Still in the comment.


Source encoding
---------------

Since the easiest way to include special characters like em dashes or copyright
signs in reST is to directly write them as Unicode characters, one has to
specify an encoding.  Sphinx assumes source files to be encoded in UTF-8 by
default; you can change this with the :confval:`source_encoding` config value.


Gotchas
-------

There are some problems one commonly runs into while authoring reST documents:

* **Separation of inline markup:** As said above, inline markup spans must be
  separated from the surrounding text by non-word characters, you have to use
  a backslash-escaped space to get around that.

* **No nested inline markup:** Something like ``*see :func:`foo`*`` is not
  possible.
  
.. XXX more?