At what point are file-local and dir-local variables applied to a newly-loaded buffer?

Question

I'm currently attempting to call the function company-org-roam--init-hook from org-mode-hook in order to enable the company-org-roam backend in org-roam buffers. In some of the files in which this hook is called, I've used a .dir-locals.el file to set org-roam-directory to a non-default value. However, when company-org-roam--init-hook is called while loading the file, it appears that org-roam-directory isn't set to its dir-local value, causing the hook not to enable the Company backend.

Is it expected that dir-local variables are applied only after major-mode hooks are run? If so, is there a way to work around this (besides a run-at-time)?

Answer 1

Is it expected that dir-local variables are applied only after major-mode hooks are run?

Yes. The local variables are normally processed in run-mode-hooks, after running the mode hooks and before running after-change-major-mode-hook.

You could use the latter to deal with your problem. Alternatively you can use hack-local-variables-hook which runs after the local variables have been processed -- refer to How can I access directory-local variables in my major mode hooks?

n.b. How and when file- and dir-local variables are processed changed in Emacs 26.1, and the linked S.O. Q&A pre-dates that change. I don't believe it affects your question, but the implementation details were different.