How to discard return value of a function?

How to discard return value of a function?

[Plamen Tanovski]

Hi,

I'm trying to write a skeleton with (search-forward) in it. But
(search-forward) always returns the point and skeleton inserts it as a
string in the buffer, which of course is not what I want. Ho can I
discard the return value of a function? I searched the elisp reference
and the net but didn't found anything. Sure, I can assign the return to
a variable, but there must be a better solution.

best regards

Re: How to discard return value of a function?

[Leo]

(progn (YOURFUNCTION ...) nil)
-- 
Sent from my Emacs

Re: How to discard return value of a function?

[jpkotta]

On Sunday, August 19, 2012 4:52:21 AM UTC-5, Leo wrote:
> (progn (YOURFUNCTION ...) nil)
> 
> -- 
> 
> Sent from my Emacs

You can also use advice, but (progn ... nil) is probably preferable.

(defun foo ()
  (interactive)
  t)

(defadvice foo (after modify-return-value activate)
  (setq ad-return-value nil))

Re: How to discard return value of a function?

[Barry Margolin]

In article <88a339ab-f737-40d1-8f3a-7cd6b66c585e@googlegroups.com>,
 jpkotta <jpkotta@gmail.com> wrote:

> On Sunday, August 19, 2012 4:52:21 AM UTC-5, Leo wrote:
> > (progn (YOURFUNCTION ...) nil)
>
> You can also use advice, but (progn ... nil) is probably preferable.
> 
> (defun foo ()
>   (interactive)
>   t)
> 
> (defadvice foo (after modify-return-value activate)
>   (setq ad-return-value nil))

If he advised search-forward to return nil, that would break lots of 
other things.  He just wants to ignore the return value in one 
particular place where he calls it.

-- 
Barry Margolin, barmar@alum.mit.edu
Arlington, MA
*** PLEASE post questions in newsgroups, not directly to me ***

Re: How to discard return value of a function?

[jpkotta]

On Monday, August 20, 2012 7:13:35 PM UTC-5, Barry Margolin wrote:
> In article <88a339ab-f737-40d1-8f3a-7cd6b66c585e@googlegroups.com>,
> 
>  jpkotta <jpkotta@gmail.com> wrote:
> 
> 
> 
> > On Sunday, August 19, 2012 4:52:21 AM UTC-5, Leo wrote:
> 
> > > (progn (YOURFUNCTION ...) nil)
> 
> >
> 
> > You can also use advice, but (progn ... nil) is probably preferable.
> 
> > 
> 
> > (defun foo ()
> 
> >   (interactive)
> 
> >   t)
> 
> > 
> 
> > (defadvice foo (after modify-return-value activate)
> 
> >   (setq ad-return-value nil))
> 
> 
> 
> If he advised search-forward to return nil, that would break lots of 
> 
> other things.  He just wants to ignore the return value in one 
> 
> particular place where he calls it.
> 
> 
> 
> -- 
> 
> Barry Margolin, barmar@alum.mit.edu
> 
> Arlington, MA
> 
> *** PLEASE post questions in newsgroups, not directly to me ***

Yeah, I realized that after I posted.  I tried to delete the post but I guess it got posted twice for some reason.

Re: How to discard return value of a function?

[Stefan Monnier]

> I'm trying to write a skeleton with (search-forward) in it. But
> (search-forward) always returns the point and skeleton inserts it as a
> string in the buffer, which of course is not what I want.

C-h f skeleton-insert RET says:

   Quoted Lisp expressions are evaluated for their side-effects.
   Other Lisp expressions are evaluated and the value treated as above.

so you can use '(search-forward ...) in your skeleton to tell skeleton
that the return value should be ignored.
Otherwise, you can also use (ignore (search-forward ...)) since `ignore'
always returns nil.


        Stefan