Dumb elisp question

Dumb elisp question

[Eric Abrahamsen]

I've made a function that takes as arguments an arbitrary format string
and a list of arguments to that string. The list of arguments is of
varying length, and the args need to be mapped through a function before
they're passed to the format string. So in the bowels of the function
there's something like:

(format fmt-str-var (mapcar (lambda (arg) (do-thing-with arg))
list-of-arguments))

Obviously, the problem is that mapcar returns a single list of strings,
not the series of atomic strings that format requires.

I've tried to solve this problem many different ways, including turning
this into a macro and using ",@", and using ",@" even when it's not a
macro, and looking at other mapping functions, and trying to make some
sort of "splice" function of my own, and… and…

Nothing works quite right. This can't be a macro because elsewhere it
needs to pass `commandp'. I can't make any of the other fixes work
properly.

Can anyone provide an elegant solution?

Thanks,
Eric



-- 
GNU Emacs 23.2.1 (i686-pc-linux-gnu, GTK+ Version 2.24.4)
 of 2011-04-04 on rothera, modified by Debian

Re: Dumb elisp question

[Le Wang]

On Fri, Sep 30, 2011 at 5:15 PM, Eric Abrahamsen
<eric@ericabrahamsen.net> wrote:
> Can anyone provide an elegant solution?

apply

-- 
Le

Re: Dumb elisp question

[Jambunathan K]

I think you are looking for this:

(apply 'format "%s %s" '("one" "two"))

> I've made a function that takes as arguments an arbitrary format string
> and a list of arguments to that string. The list of arguments is of
> varying length, and the args need to be mapped through a function before
> they're passed to the format string. So in the bowels of the function
> there's something like:
>
> (format fmt-str-var (mapcar (lambda (arg) (do-thing-with arg))
> list-of-arguments))
>
> Obviously, the problem is that mapcar returns a single list of strings,
> not the series of atomic strings that format requires.


> I've tried to solve this problem many different ways, including turning
> this into a macro and using ",@", and using ",@" even when it's not a
> macro, and looking at other mapping functions, and trying to make some
> sort of "splice" function of my own, and… and…
>
> Nothing works quite right. This can't be a macro because elsewhere it
> needs to pass `commandp'. I can't make any of the other fixes work
> properly.
>
> Can anyone provide an elegant solution?
>
> Thanks,
> Eric

-- 

Re: Dumb elisp question

[Eric Abrahamsen]

On Fri, Sep 30 2011, Jambunathan K wrote:

> I think you are looking for this:
>
> (apply 'format "%s %s" '("one" "two"))

GAH! I've learned this like four times, hopefully this time it will
stick. Thanks to both of you.

E

-- 
GNU Emacs 23.2.1 (i686-pc-linux-gnu, GTK+ Version 2.24.4)
 of 2011-04-04 on rothera, modified by Debian

Re: Dumb elisp question

[Le Wang]

On Fri, Sep 30, 2011 at 9:12 PM, Eric Abrahamsen
<eric@ericabrahamsen.net> wrote:
> GAH! I've learned this like four times, hopefully this time it will
> stick. Thanks to both of you.

You keep using words like didactic, and we'll keep answering your
elisp questions.  It's a fair trade.


-- 
Le