CODEWITHSUNDEEP
emacs
cerhovice
cerhovice

Reputation: 686

how to get a variable to represent a function name for "symbol-function()"

I am learning how to program in emacs lisp. I thought I would write a simple function that prints a function definition to the messages buffer. This works fine: 

(let (
(fDefAsString (symbol-function 'scroll-down)) 
)
(message "%s" fDefAsString)
(switch-to-buffer-other-frame "*Messages*"))

but I wanted this to be a function that could take an argument, the argument being the name of the function whose definition I want to see. So I tried this:

(defun message-function-definition (nameOfFunction)
(let (
(fDefAsString (symbol-function 'nameOfFunction)) 
)
(message "%s" fDefAsString)
(switch-to-buffer-other-frame "*Messages*")))

and then I wrote this:

(message-function-definition 'scroll-down)

Then I ran "eval-buffer".

I keep getting this error:

Debugger entered--Lisp error: (void-function nameOfFunction) symbol-function(nameOfFunction) (let ((fDefAsString ...)) (message "%s" fDefAsString) (switch-to-buffer-other-frame "Messages")) message-function-definition(scroll-down) eval((message-function-definition (quote scroll-down))) eval-last-sexp-1(nil) eval-last-sexp(nil) call-interactively(eval-last-sexp nil nil) recursive-edit() byte-code("\306 @\307=\203!

I've tried quoting, unquoting, and I've tried to use "nameOfFunction" but I can not get this to work. What am I doing wrong?

Upvotes: 1

Views: 303

Answers (1)

event_jr
event_jr

Reputation: 17707

Did you try unquoting? This works for me:

(defun message-function-definition (nameOfFunction)
  (let ((fDefAsString (symbol-function nameOfFunction)))
    (message "%s" fDefAsString)
    (switch-to-buffer-other-frame "*Messages*")))

Some hints:

  1. Your code is not indented correctly. If you select the region and re-indent with tab, it'll be easier to read.

  2. You should spend a couple of hours working through the "Emacs Lisp Intro", you will have a much better idea of how things work in Emacs-lisp, rather than figuring it all by asking one question at a time on StackOverflow.

  3. symbol-function is not designed to show a human readable definition of the function. In most cases you won't really see anything useful.

    Try this:

    (find-function-other-window 'scroll-down)

Upvotes: 1

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