Source Constants

The substitutions built into restructuredText have a number of limitations and quirks. For example, they cannot be used to substitute content inside of code blocks, and cannot contain links.

The MongoDB Documentation Project has an extension called source_constants which allows you to substitute constants anywhere in a page before docutils begins its parse stage.

Example

In your conf.py, add 'source_constants' to the extensions list, and define a source_constants dict:

1 source_constants = {
2     'package-branch': 'testing',
3     'package-name-org': 'mongodb-org',
4     'version': version
5 }

You may then use these constants in your restructuredText files:

Create the
``/etc/apt/sources.list.d/mongodb-org-4.4.0.list``
list file using the command appropriate for your version of Ubuntu:
.. code-block:: sh
   echo "deb [ arch=amd64 ] https://repo.mongodb.org/apt/ubuntu \
        trusty/mongodb-org/testing multiverse" \
        | sudo tee /etc/apt/sources.list.d/mongodb-org-4.0.list

Comparison with Other Variable Syntaxes

	`4.0`	`{{version}}`	`\|version\|`
Description	`source_constants`	Giza YAML substitutions	restructuredText substitutions
Locations	Can be used anywhere	Can only be used within YAML files	May only be used in a subset of restructuredText syntactical locations
Valid Content	Anything	Anything	May not be used to inject links or other non-trivial types of content
Mutable	Can currently only be defined in `conf.py`	Yes. Can be overridden with Giza's content inheritance mechanism	Can only be defined once per page context
Warns if undefined	Yes	No	Yes

Back

Options / Settings

Substitutions

1	source_constants = {
2	'package-branch': 'testing',
3	'package-name-org': 'mongodb-org',
4	'version': version
5	}