Persist state across directives (with sphinx.environment.BuildEnvironment.current_document?)

[nlgranger]

I'm trying to write an extension which runs code to be rendered, but I'd like to be able to split the code across several directives and have a shared state between them (more specifically a share prolog for imports and initialisation code). I don't know where to store it.

This is similar to what the ..testsetup directive does for ..doctest, except that doctest uses a specific renderer to figure out the relationship between the directives.

The documentation of sphinx.environment.BuildEnvironment.current_document says it exists while processing the current document, so I suppose I could use that. However the documentation is a bit terse, I'm unsure about its scope.