what does (interactive "P") do?

what does (interactive "P") do?

[seberino]

I just saw (interactive "P") in a .emacs and
wondered what it did.  I assume (interactive)
lets a user run a function v. just being
run from another function.

What extra functiononality does the "P" give you?

Chris
-- 
_______________________________________

Dr. Christian Seberino
SPAWAR Systems Center San Diego
Code 2363
49590 Lassing Road, Room A339
San Diego, CA 92152-6147
U.S.A.

Phone: (619) 553-7940
Fax:   (619) 553-1269
Email: seberino@spawar.navy.mil
_______________________________________

Re: what does (interactive "P") do?

[Michael Slass]

seberino@spawar.navy.mil writes:

>I just saw (interactive "P") in a .emacs and
>wondered what it did.  I assume (interactive)
>lets a user run a function v. just being
>run from another function.
>
>What extra functiononality does the "P" give you?
>
>Chris
>-- 

You have just crossed the threshold in your lisp programming
sophistication where the manual is a must.  Go get the elisp-intro and
elisp manuals from www.fsf.org.  They're available in info format,
which means that you can read them from within emacs, and evaluate
(execute) the samples as you go.

-- 
Mike Slass

Re: what does (interactive "P") do?

[Oliver Scholz]

seberino@spawar.navy.mil writes:

> I just saw (interactive "P") in a .emacs and
> wondered what it did.  I assume (interactive)
> lets a user run a function v. just being
> run from another function.

It declares that the function is a command. That is, a user may run it
via M-x and it may be bound to a keystroke.

> What extra functiononality does the "P" give you?

With "P" in the spec string of `interactive' the prefix (`C-u ...') is
passed in raw form as an argument to the function. It is typically
used in forms like

(my-fancy-function (prefix)
  (interactive "P")
  ...
  (if (prefix)
      (do-something)
    (do-something-different))
   ...)

See `C-h f interactive RET' for a complete list of code letters for
`interactive'.

    Oliver
-- 
1 Frimaire an 211 de la Révolution
Liberté, Egalité, Fraternité!