Sphinx Paramlinks

A Sphinx extension which allows :param: directives within Python documentation to be linkable.

This is an experimental extension that's used by the SQLAlchemy project and related projects.

Configuration

Just turn it on in conf.py:

extensions = [
            'sphinx_paramlinks',

            # your other sphinx extensions
            # ...
        ]

Since version 0.5.3, you can modify how clickable hyperlinks are placed around the names of the parameter using the paramlinks_hyperlink_param setting in conf.py:

paramlinks_hyperlink_param='name'

This parameter accepts the following values:

• 'none': No link will be be inserted. The parameter still has a target attached to it so that you can e.g. jump to it from the search.
• 'name': The parameter name is a clickable hyperlink.
• 'link_symbol': A clickable link symbol is inserted after the parameter name (but before an eventual type specification). By default, this symbol only shows when hovering the parameter description (see below)
• 'name_and_symbol': link both the name and also generate a link symbol.

The default is paramlinks_hyperlink_param = 'link_symbol'.

Features

• :param: directives within Sphinx function/method descriptions will be given a paragraph link so that they can be linked to externally.

• A new text role :paramref: is added, which works like :meth:, :func:, etc. Just append the parameter name as an additional token:

  :paramref:`.EnvironmentContext.configure.transactional_ddl`
  

  The directive makes use of the existing Python role to do the method/function lookup, searching first the :meth:, then the :class:, and then the :func: role; then the parameter name is applied separately to produce the final reference link. (new in 0.3.4, search for :meth: / :func: / :class: individually rather than using :obj: which catches lots of things that don't have parameters)

• The paramlinks are also added to the master index as well as the list of domain objects, which allows them to be searchable through the searchindex.js system. (new in 0.3.0)

Stylesheet

The paragraph link involves a short stylesheet, to allow the links to be visible when hovered. This sheet is called sphinx_paramlinks.css and the plugin will copy it to the _static directory of the output automatically. The stylesheet is added to the css_files list present in the template namespace for Sphinx via the Sphinx.add_stylesheet() hook.

Customization

To customize the link styling, you can override the configuration of sphinx_paramlinks.css by adding a custom style sheet via:

app.add_css_file("path/to/custom.css")

If the parameter name is a hyperlink, the HTML code will look something like this:

<a class="paramname reference internal" href="#package.method.params.parameter_name">
     <strong>parameter_name</strong>
</a>

The class paramname is defined by sphinx-paramlinks and can be used to customize the styling.

If a link symbol is inserted after the hyperlink, the HTML code will look something like this:

<a class="paramlink headerlink reference internal" href="#package.method.params.parameter_name">¶</a>

The class paramlink is defined by sphinx-paramlinks and can be used to customize the styling.

Compatibility

Python Compatibility

sphinx-paramlinks is fully Python 3 compatible.

Sphinx Compatibility

I've tried very hard to make as few assumptions as possible about Sphinx and to use only very simple public APIs, so that architectural changes in future Sphinx versions won't break this plugin. To come up with this plugin I spent many hours with Sphinx source and tried many different approaches to various elements of functionality; hopefully what's here is as simple and stable as possible based on the current extension capabilities of Sphinx.

One element that involves using a bit of internals is the usage of the sphinx.domains.python.PyXRefRole class, which is currently the Sphinx class that defines roles for things like :meth:, :func:, etc. The object is used as-is in order to define the :paramref: role; the product of this role is later transformed using standard hooks.

Another assumption is that in order to locate the RST nodes Sphinx creates for the :param: tags, we look at nodes.strong, assuming that this is the type of node currently used to render :param: within RST. If this changes, or needs to be expanded to support other domains, this traversal can be opened up as needed. This part was difficult as Sphinx really doesn't provide any hooks into how the "Info Field List" aspect of domains is handled.

Overall, the approach here is to apply extra information to constructs going into the Sphinx system, then do some transformations as the data comes back out. This relies on as little of how Sphinx does its thing as possible, rather than going with custom domains and heavy use of injected APIs which may change in future releases.