3

I have:

(add-hook 'text-mode-hook 'turn-on-auto-fill)

but in lisp/nxml/nxml-mode.el:

(define-derived-mode nxml-mode text-mode "nXML"

All XML files is opened with auto-fill-mode. That is inconvenient because XML file under source control and shouldn't drastically change on edits.

How can I disable auto-fill for nxml? Should I remove:

(add-hook 'text-mode-hook 'turn-on-auto-fill)

or add some workaround for nxml?

1 Answer 1

4

Prevent hooks from parent mode in derived mode

Not trivial. I certainly can't think of a nice approach. You may find https://stackoverflow.com/a/19295380 of interest, though.

How can I disable auto-fill for nxml?

The trivial approach is to simply switch it off in nxml-mode-hook. The mode will be switched on, and almost immediately switched off again.

(add-hook 'nxml-mode-hook 'turn-off-auto-fill)

Alternatively, replace 'turn-on-auto-fill in your code with a custom function that does what you really want:

(defun my-turn-on-auto-fill-maybe ()
  "Turns on `auto-fill-mode' unless I don't want it."
  (let ((exceptions '(nxml-mode)))
    (unless (apply 'derived-mode-p exceptions)
      (auto-fill-mode 1))))
2
  • From your explanation I see that (add-hook 'text-mode-hook 'turn-on-auto-fill) is bad defaults. It's better to turn on where I need then add exceptions.
    – gavenkoa
    Apr 27, 2017 at 14:05
  • FWIW, the first option does retain the flyspell-mode messages, i.e., the minibuffer talks about flyspell-mode even though it's disabled, which confused me a bit.
    – Reid
    Mar 21 at 23:02

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