auto-minor-mode

This package lets you enable minor modes based on file name and contents. To find the right modes, it checks filenames against patterns in auto-minor-mode-alist and file contents against auto-minor-mode-magic-alist. These work like the built-in Emacs variables auto-mode-alist and magic-mode-alist.

Unlike major modes, all matching minor modes are enabled, not only the first match.

A reason you might want to use it:

(add-to-list 'auto-minor-mode-alist '("-theme\\.el\\'" . rainbow-mode))

There's intentionally no equivalent of interpreter-mode-alist. Interpreters should determine the major mode. Relevant minor modes can then be enabled by major mode hooks.

Minor modes are set whenever set-auto-mode, the built-in function responsible for handling automatic major modes, is called.

use-package Integration

If you also use use-package, two new keywords are added, :minor and :magic-minor, which register entries in these alists. You must load (and not defer) auto-minor-mode before using these keywords.

License

This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.