Doc/documenting/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.

Note that Sphinx disables the use of enumerated lists introduced by alphabetic
or roman numerals, such as ::

   A. First item
   B. Second item
   

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, to be able to include 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:`doc-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, we use this convention:

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


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.


Footnotes
---------

For footnotes, use ``[#]_`` 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 [#]_ dolor sit amet ... [#]_

   .. rubric:: Footnotes

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

You can also explicitly number the footnotes for better context.


Comments
--------

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

All Python documentation source files must be in UTF-8 encoding, and the HTML
documents written from them will be in that encoding as well.


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
  an escaped space to get around that.

.. XXX more?