Question

I want to set the destination directory for emacs lisp byte compilation using relative path such as ../foo. I figured out I should use byte-compile-dest-file-function, but do not know how to set it. How can I set it?

Answer 1

To set the byte-compile-dest-function variable, you can use either customize-variable interactively, or setq in your init file. Since you’ll have to write a function doing the job either way, I would recommand the latter, so that everything is in the same place in your init file.

For example:

(defun my-dest-function (filename)
  (concat (file-name-directory filename)
          "../"
          (file-name-sans-extension (file-name-nondirectory filename))
          ".elc"))
(setq byte-compile-dest-file-function 'my-dest-function)