Readability is a primary focus for Python developers, in both project and code documentation. Following some simple best practices can save both you and others a lot of time.
README file at the root directory should give general information
to both users and maintainers of a project. It should be raw text or
written in some very easy to read markup, such as reStructuredText
or Markdown. It should contain a few lines explaining the purpose of the
project or library (without assuming the user knows anything about the
project), the url of the main source for the software, and some basic credit
information. This file is the main entry point for readers of the code.
INSTALL file is less necessary with Python. The installation
instructions are often reduced to one command, such as
python setup.py install and added to the
LICENSE file should always be present and specify the license
under which the software is made available to the public.
TODO file or a
TODO section in
README should list the
planned development for the code.
CHANGELOG file or section in
README should compile a short
overview of the changes in the code base for the latest versions.
Depending on the project, your documentation might include some or all of the following components:
- An introduction should show a very short overview of what can be done with the product, using one or two extremely simplified use cases. This is the thirty-second pitch for your project.
- A tutorial should show some primary use cases in more detail. The reader will follow a step-by-step procedure to set-up a working prototype.
- An API reference is typically generated from the code (see docstrings). It will list all publicly available interfaces, parameters, and return values.
- Developer documentation is intended for potential contributors. This can include code convention and general design strategy of the project.
Sphinx is far and away the most popular Python documentation tool. Use it. It converts reStructuredText markup language into a range of output formats including HTML, LaTeX (for printable PDF versions), manual pages, and plain text.
There is also great, free hosting for your Sphinx docs: Read The Docs. Use it. You can configure it with commit hooks to your source repository so that rebuilding your documentation will happen automatically.
Code Documentation Advice¶
Comments clarify the code and they are added with purpose of making the
code easier to understand. In Python, comments begin with a hash
(number sign) (
In Python, docstrings describe modules, classes, and functions:
def square_and_rooter(x): """Returns the square root of self times self.""" ...
In general, follow the comment section of PEP 8#comments (the “Python Style Guide”).
Docstrings and Magic¶
Some tools use docstrings to embed more-than-documentation behavior, such as unit test logic. Those can be nice, but you won’t ever go wrong with vanilla “here’s what this does.”
Docstrings versus Block comments¶
These aren’t interchangeable. For a function or class, the leading comment block is a programmer’s note. The docstring describes the operation of the function or class:
# This function slows down program execution for some reason. def square_and_rooter(x): """Returns the square root of self times self.""" ...
Further reading on docstrings: PEP 257
You might see these in the wild. Use Sphinx.
- Pycco is a “literate-programming-style documentation generator” and is a port of the node.js Docco. It makes code into a side-by-side HTML code and documentation.
- Ronn builds unix manuals. It converts human readable textfiles to roff for terminal display, and also to HTML for the web.
- MkDocs is a fast and simple static site generator that’s geared towards building project documentation with Markdown.