4. Documenting ARMI

ARMI uses the Sphinx documentation system to compile the web-based documentation from in-code docstrings and hand-created ReStructedText files. This provides several benefits:

• We can revise and track the documentation in lock-step with the code itself, in the same source code repository

• We can make use of hyperlinked cross-references that stay up to date as the code is expanded or refactored.

• We can run specific code tests during documentation building to ensure the documentation examples remain valid

• We can auto-generate class diagrams based on the latest status of the code

We use some special Sphinx plugins that run the tutorial jupyter notebooks during documentation build with the most up-to-date code.

4.1. Building the documentation

Before building documentation, ensure that you have installed the test requirements into your ARMI virtual environment with:

pip install -e .[test]

You also need to have the following utilities available in your PATH:

• Graphviz

• Pandoc

If you want to build the documentation into a PDF using the Sphinx LaTeX builder, you also need:

• LaTeX (MikTeX on Windows)

• ImageMagick

The documentation depends on at least one submodule as well, so you must be sure it is available in your source tree with:

git submodule update --init

To build the ARMI documentation as html, go to the doc folder and run:

make html

This will invoke Sphinx and generate a series of html files in the _build/html folder. Open up index.html to see the documentation from there. A copy of the documentation is hosted online at https://terrapower.github.io/armi/.

You can suggest a change to the built documentation by copying the _build files to a clone of the documentation repository with a command like:

rsync -ahv --delete _build/html/ path/to/terrapower.github.io/armi

4.2. Documentation for ARMI plugins

The following subsections apply to documentation for ARMI plugins.

4.2.1. Linking to ARMI documentation from plugins

ARMI plugin documentation can feature rich hyperlinks to the ARMI API documentation with the help of the intersphinx Sphinx plugin. The ARMI plugin documentation config file should add "sphinx.ext.intersphinx", to its active Sphinx plugin list, and change the default config to read:

intersphinx_mapping = {
    "python": ("https://docs.python.org/3", None),
    "armi": ("https://terrapower.github.io/armi/", None),
}

Now you can link to the ARMI documentation with links like:

:doc:`armi:developer/documenting`
:py:mod:`armi.physics.executers`

4.2.2. Automatically building apidocs of namespace packages

Activating the "sphinxcontrib.apidoc", Sphinx plugin enables plugin API documentation to be built with the standard make html Sphinx workflow. If your ARMI plugin is a namespace package, the following extra config is required:

apidoc_extra_args = ["--implicit-namespaces"]

4.3. Updating the Gallery

The sphx_glr_gallery is a great way to quickly highlight neat features and uses of ARMI. To add a new item to the gallery, add your example code (including the required docstring) to the doc/gallery-src folder in the ARMI source tree. The example will be added to the gallery during the next documentation build.

4.4. Using Jupyter notebooks

For interactive tutorials, it’s convenient to build actual Jupyter notebooks and commit them to the documentation to be rendered by Sphinx using the nbsphinx plugin. When this is done, notebooks without any output should be committed to the repository so that Sphinx actually executes the notebooks with the up-to-date code when the documentation is built. To do this, you can clean the output with:

jupyter nbconvert --ClearOutputPreprocessor.enabled=True --inplace mynotebook.ipynb

This should clear the output and overwrite the file. If this doesn’t work, you can clear all output cells in the notebook web interface itself before committing the file.