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# Python-Markdown

This is a Python implementation of John Gruber’s Markdown. It is almost completely compliant with the reference implementation, though there are a few very minor differences. See John’s Syntax Documentation for the syntax rules.

See the installation instructions to get started.

## Goals

The Python-Markdown project is developed with the following goals in mind:

- Maintain a Python 2 and Python 3 library (with an optional CLI wrapper) suited to use in web server environments (never raise an exception, never write to stdout, etc.) as an implementation of the markdown parser that follows the syntax rules and the behavior of the original (markdown.pl) implementation as reasonably as possible (see differences for a few exceptions).

- Provide an Extension API which makes it possible to change and/or extend the behavior of the parser.

## Features

In addition to the basic markdown syntax, Python-Markdown supports the following features:

- International Input

  Python-Markdown will accept input in any language supported by Unicode including bi-directional text. In fact the test suite includes documents written in Russian and Arabic.

- Extensions

  Various extensions are provided (including extra) to change and/or extend the base syntax. Additionally, a public Extension API is available to write your own extensions.

- Output Formats

  Python-Markdown can output documents in HTML4, XHTML and HTML5. See the Library Reference for details.

- Command Line Interface

  In addition to being a Python Library, a command line script is available for your convenience.

## Differences

While Python-Markdown strives to fully implement markdown as described in the syntax rules, the rules can be interpreted in different ways and different implementations occasionally vary in their behavior (see the Babelmark FAQ for some examples). Known and intentional differences found in Python-Markdown are summarized below:

- Middle-Word Emphasis

  Python-Markdown defaults to ignoring middle-word emphasis. In other words, `some_long_filename.txt` will not become `some<em>long</em>filename.txt`. This can be switched off if desired. See the Library Reference for details.

- Indentation/Tab Length

  The syntax rules clearly state that when a list item consists of multiple paragraphs, “each subsequent paragraph in a list item must be indented by either 4 spaces or one tab” (emphasis added). However, many implementations do not enforce this rule and allow less than 4 spaces of indentation. The implementers of Python-Markdown consider it a bug to not enforce this rule.

  This applies to any block level elements nested in a list, including paragraphs, sub-lists, blockquotes, code blocks, etc. They must always be indented by at least four spaces (or one tab) for each level of nesting.

  In the event that one would prefer different behavior, tab_length can be set to whatever length is desired. Be warned however, as this will affect indentation for all aspects of the syntax (including root level code blocks).

- Consecutive Lists

  While the syntax rules are not clear on this, many implementations (including the original) do not end one list and start a second list when the list marker (asterisks, pluses, hyphens, and numbers) changes. For consistency, Python-Markdown maintains the same behavior with no plans to change in the foreseeable future. That said, the Sane List Extension is available to provide a less surprising behavior.

## Support

You may ask for help and discuss various other issues on the mailing list and report bugs on the bug tracker.

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