Documentation style

There are two types of documentation in SMTK: Doxygen documentation written as comments in C++ code and Sphinx documentation written in reStructuredText files (and optionally Python documentation strings). The former is used to create reference documentation; the latter is used for the user’s guide and tutorials.

The following rules apply to writing documentation:

  • Header files should contain the Doxygen documentation for the class as a whole plus any enums declared outside classes, however:

  • Implementation files should contain the Doxygen documentation for class methods. This keeps the documentation next to the implementation (making it easier to keep up-to-date). It also makes the headers easier to read.

  • If a class provides high-level functionality, consider writing some user-guide-style documentation in the User’s Guide (in doc/userguide.rst) or a tutorial (in doc/tutorials/). Tutorials should include a working example that is run as a CTest test. The code in the example should be referenced indirectly by the tutorial so that the the exact code that is tested appears as the text of the tutorial.

  • In reStructuredText documents, you should use the doxylinks module to link to the Doxygen documentation when appropriate. Examples: :smtk:`UUID` produces this link: UUID while the :smtk:`Resource <smtk::attribute::Resource>` variant can produce links (Resource in this case) whose text varies from the classname or whose classnames are ambiguous because of namespaces. The leading :smtk: names the tag file holding the class and function definitions; other third-party-library tag files may be added in the future.

    You will be tempted to make every word that is a classname into a Doxygen link; do not do this. Instead, provide a Doxygen link at the first occurrence of the classname in a topic’s discussion — or at most in a few key places. Otherwise the documentation becomes difficult to read due to conflicting text styles.

  • In reStructuredText, when you wish to show code in-line but it is inappropriate to link to Doxygen documentation, use the :cxx: role for C++ (e.g., if (foo)), the :file: role for paths to files (e.g., doc/index.rst), and so on. See the documentation for roles in reStructuredText for more information.

  • Note that the user’s guide and tutorials are both included in the top-level doc/index.rst file parsed by Sphinx. Several extensions to Sphinx are used and these are configured in doc/

To get started documenting your code, you should at least have doxygen and graphviz installed. These are available using Homebrew on Mac OS X, your Linux distribution’s package manager, or by binary installer from the source maintainer on Windows.

Additionally there are a number of Python packages that provide Sphinx, docutils, and other packages required to generate the user’s guide. These packages can all be installed with pip:

# The basic utilities for processing the user's guide:
sudo pip install docutils
sudo pip install Sphinx
# For linking to external Doxygen docs:
sudo pip install sphinxcontrib-doxylink
# For creating inline class docs from Doxygen XML:
sudo pip install breathe
# For the default theme:
sudo pip install sphinx-rtd-theme
# For syntax highlighting:
sudo pip install Pygments
# For activity diagrams:
sudo pip install sphinxcontrib-actdiag

If you are unfamiliar with the documentation packages here, see these links for examples of their use (or use SMTK by example):