How to automatically remove a hook provided by a minor mode after disabling that mode?

Question

I want to write a minor which evaluates some code in the buffer after saving a file. I activate after-save-hook for this mode:

(add-hook 'my-minor-mode-name-hook #'(lambda () (add-hook 'after-save-hook #'a-func-from-my-minor-mode))

Everything works as intended until I disable the minor mode with the command  my-minor-mode-name. I get the message that the mode has been disabled but after-save-hook is still active (although evaluating after-save-hook in the buffer indicates that a-func-from-my-minor-mode is not on the list).

I want a behaviour where disabling the minor mode removes automatically the hook -- how should I fix that?

Stefan · Answer

The minor mode's hook is called both when activating and deactivating the minor mode, so how 'bout
(add-hook 'my-minor-mode-name-hook
          (lambda ()
            (if my-minor-mode-name
                (add-hook 'after-save-hook #'a-func-from-my-minor-mode nil 'local)
              (remove-hook 'after-save-hook #'a-func-from-my-minor-mode 'local))))

Note that your calls to add-hook are both global, so even though you only add to after-save-hook when the minor mode is called, this addition applies to all buffers.  Maybe that was indeed what you wanted, but I assumed it's not in the above example code.

How to automatically remove a hook provided by a minor mode after disabling that mode?

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