Re: Passing a list of symbols to function argument

[Heime via Users list for the GNU Emacs text editor <help-gnu-emacs@gnu.org>]

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On Saturday, November 30th, 2024 at 7:54 AM, Stephen Berman <stephen.berman@gmx.net> wrote:

> On Fri, 29 Nov 2024 17:34:01 +0000 Heime via Users list for the GNU Emacs text editor help-gnu-emacs@gnu.org wrote:
> 
> > Why do I get
> > 
> > Wrong type argument: stringp, tabtrail
> > 
> > When using the call
> > 
> > (poalatuk '(72 tabtrail global))
> > 
> > to the function
> > 
> > (defun poalatuk (actm-seqr)
> > 
> > (interactive
> > (let* ( (colw (read-number "Line Column: " 72))
> > (cseq '("extended" "disable" "tabtrail"))
> > (rsel (completing-read "Selector: " cseq nil t "tabtrail"))
> > (scope (completing-read "Scope: "
> > '("global" "local") nil t "local")) )
> > 
> > ;; Pass a single list as argument
> > (list (list colw rsel scope))) )
> > 
> > ;; -------------------------------------------------------------
> > 
> > (message "poalatuk: %S" actm-seqr)
> > 
> > (let* ( (colw (nth 0 actm-seqr)) ;; Extract column width.
> > (rsel (intern (nth 1 actm-seqr))) ;; Extract mode selector.
> 
> ^^^^^^^^^^^^^^^^^^^^^^^^^^
> 
> The error happens here. You passed '(72 tabtrail global) as the value
> of the argument actm-seqr, so (nth 1 actm-seqr) returns the symbol
> `tabtrail'. But` intern' takes a string and returns the symbol (in the
> obarray) whose name is given by the string.
> 
> Steve Berman

I want the function to accept both symbols and strings.  intern must then 
be applied only when a string is passed.  Which undoubtedly needs a conditional
check.

Perhaps I should also test whether the argument is a symbol or do the if
and pcase handle errors (because the commands will be skipped).

(let* ((colw (nth 0 actm-seqr))
       (rsel (if (stringp (nth 1 actm-seqr)) 
                 (intern (nth 1 actm-seqr))
               (nth 1 actm-seqr)))
       (scope (if (stringp (nth 2 actm-seqr)) 
                  (intern (nth 2 actm-seqr))
                (nth 2 actm-seqr))))