# Showing code examples

Examples of Python source code or interactive sessions are represented using standard reST literal blocks. They are started by a :: at the end of the preceding paragraph and delimited by indentation.

Representing an interactive session requires including the prompts and output along with the Python code. No special markup is required for interactive sessions. After the last line of input or output presented, there should not be an "unused" primary prompt; this is an example of what not to do:

>>> 1 + 1
2
>>>


Syntax highlighting is done with Pygments (if it's installed) and handled in a smart way:

• There is a "highlighting language" for each source file. Per default, this is 'python' as the majority of files will have to highlight Python snippets, but the doc-wide default can be set with the :confval:highlight_language config value.

• Within Python highlighting mode, interactive sessions are recognized automatically and highlighted appropriately. Normal Python code is only highlighted if it is parseable (so you can use Python as the default, but interspersed snippets of shell commands or other code blocks will not be highlighted as Python).

• The highlighting language can be changed using the highlight directive, used as follows:

.. highlight:: c


This language is used until the next highlight directive is encountered.

• For documents that have to show snippets in different languages, there's also a :rst:dir:code-block directive that is given the highlighting language directly:

.. code-block:: ruby

Some Ruby code.


The directive's alias name :rst:dir:sourcecode works as well.

• The valid values for the highlighting language are:

• none (no highlighting)
• python (the default when :confval:highlight_language isn't set)
• guess (let Pygments guess the lexer based on contents, only works with certain well-recognizable languages)
• rest
• c
• ... and any other lexer name that Pygments supports.
• If highlighting with the selected language fails, the block is not highlighted in any way.

## Line numbers

If installed, Pygments can generate line numbers for code blocks. For automatically-highlighted blocks (those started by ::), line numbers must be switched on in a :rst:dir:highlight directive, with the linenothreshold option:

.. highlight:: python
:linenothreshold: 5


This will produce line numbers for all code blocks longer than five lines.

For :rst:dir:code-block blocks, a linenos flag option can be given to switch on line numbers for the individual block:

.. code-block:: ruby
:linenos:

Some more Ruby code.


## Includes

Footnotes

 [1] There is a standard .. include directive, but it raises errors if the file is not found. This one only emits a warning.