Make complex setting values like latex_documents overridable

[shumpohl]

Is your feature request related to a problem? Please describe.
I want to override latex specific settings when invoking sphinx-build to embed the generated latex in an external document. I do not want to edit the original conf.py. First I tried a dedidcated conf.py but ran into problems with relative paths so I decided to try the command line settings override.

The --define documentation nicely explains how to override dict and list type values. However, latex_documents is a list of tuples which are not handled correctly.

Describe the solution you'd like
I do not have a favourite solution.

My original problem of patching "conf.py" without file modification can also be solved by additional "appendable" python code.

Describe alternatives you've considered

• Make list entries addressable by <name>.<index> notation
• Intoduce dedicated syntax for latex_document entry that does not use ,
• Add a dedicated --json-settings argument which accepts a JSON object. This can be tricky to use because shells treat quotes differently.

Additional context
Parsing of list type values (btw: There is no way to escape the ","):

sphinx/sphinx/config.py

Line 342 in 6471027

elif isinstance(default, list):

Interpretation of list elements as sequence in the latex builder:

sphinx/sphinx/builders/latex/__init__.py

Line 150 in 6471027

preliminary_document_data = [list(x) for x in self.config.latex_documents]

[mgeier]

First I tried a dedidcated conf.py but ran into problems with relative paths

I know this is fiddly, but I made it work in one instance like this: https://github.com/mgeier/diss/blob/3c5dcb7312b5132efccc4cbc7a55facf654f7c58/sphinx-splines/conf.py#L7-L8
Maybe that helps?

[shumpohl]

Thank you very much! That looks like it fits my usecase and solves some other problems I have been finding worse solutions for.

EDIT: I had to extend it by

for idx, html_path in enumerate(html_static_path):
    html_path = pathlib.Path(html_path)
    if not html_path.is_absolute():
        html_path = (original_conf_py.parent / html_path).resolve()
        html_static_path[idx] = str(html_path)