CODEWITHSUNDEEP
emacselispadvising-functionsdefadvice
Falko
Falko

Reputation: 1038

Emacs Lisp, how to mapcar a macro, and evaluate one of the arguments

Bob Glickstein describes in "Writing GNU Emacs Extensions", chapter 3, a way to advise scroll functions. (He suggests to make them reversible, so we have to save the state before scrolling.)

E.g. for scroll-up-command this advising is done like so

(defadvice scroll-up-command (before reversibilate activate compile)
   "If it wants to be reversible, it must save the former state."
   (save-before-scroll))

Well. I of course have to do this to all of the scroll commands. So I'd like to make a sequence of them, and want to advise them together.

(setq reversible-scroll-commands 
  [scroll-up-command 
   scroll-down-command 
   scroll-left-command 
   scroll-right-command])

(I use a vector to save 5 quotes.)

But now I'm stuck.

(mapcar 
  (lambda (fun-name)
    (defadvice fun-name (before reversibilate activate compile)
       "If it wants to be reversible, it must save the former state."
       (save-before-scroll)))
   reversible-scroll-commands)

will advise the (non existing) function fun-name four times, as defadvice is a macro, and doesn't evaluate fun-name.

Is there any way to do it?

(I'm using Emacs 24)

Upvotes: 5

Views: 1218

Answers (1)

legoscia
legoscia

Reputation: 41528

Untested:

(mapcar 
  (lambda (fun-name)
    (eval `(defadvice ,fun-name (before reversibilate activate compile)
             "If it wants to be reversible, it must save the former state."
             (save-before-scroll))))
   reversible-scroll-commands)

See the section about backquotes in the elisp manual.

Upvotes: 3

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