Similar to the somewhat neat, but in the end too clunky, hydra-goto-line, I'd like to customize goto-line to enable linum-mode, but only during the function call.
I tried add-advice, :before and :after, but nothing kinda happened. So what's the proper way to enable a minor-mode during a single function call?
I probably borrowed this from somewhere, but darned if I remember where:
(defun goto-line-with-feedback ()
"Show line numbers temporarily, while prompting for the line number input."
(interactive)
(defvar goto/line 0)
(unwind-protect
(progn
(linum-mode 1)
(setq goto/line (read-number "Goto line: "))
(goto-char (point-min))
(forward-line (1- goto/line)))
(linum-mode -1)))
I rebind M-g to that; works a treat.
(Note that if you're using Emacs 26, you should use display-line-numbers-mode instead of linum-mode -- just swapping the two function calls is all you need to do.)
As a general rule — to try to address your question in a more generic, "teach you to fish" kind of way — any function of the form foo-mode in Emacs will take a positive argument to unconditionally enable the mode, and a negative (or sometimes nil) argument to unconditionally disable it. The best way to validate that is to read the documentation for the function (C-h f then the function name).
