Re: Passing a list of symbols to function argument

[Heime]

On Saturday, November 30th, 2024 at 9:29 AM, Stephen Berman 
<stephen.berman@gmx.net> wrote:

> > > > 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))))
> > > 
> > > This seems fine; `if' does not do error handling, nor does` pcase' AFAIK
> > > (but there are several variants and extensions of pcase, and I'm not too
> > > familiar with them, so maybe some of them do error handling), but
> > > `condition-case' is the basic error handling form in Elisp. 
> > > Alternatively, since the error only happens in noninteractive calls 
> > > (since interactive calls use` completing-read', which returns strings),
> > > you could condition on `called-interactively-p'.
> > > 
> > > Steve Berman
> > 
> > For the interactive call I want to pass the three values so that
> > actm-seqr will be a list of three objects.
> > 
> > Thus I do
> > 
> > (list (list colw rsel scope))
> > 
> > Would the above be correct?
> 
> 
> Yes.
> 
> > With only (list colw rsel scope) emacs does complain.
> 
> 
> Because that means the interactive call passes three arguments, but your
> definition of `poalatuk' only specifies one argument parameter.
> 
> > I wonder whether actm-seqr will give me ((72 tabtrail global))
> > and not (72 tabtrail global).
> 
> I don't know what you mean; actm-seqr is the function parameter, a
> variable whose value is whatever is passed on calling the function
> either interactively or noninteractively.

For the interactive part, would returning

   (list (list colw (intern rsel) (intern scope)))

pass

   ((72 tabtrail global))  ; list with single element being a list

or 

  (72 tabtrail global)  ; list of three entries

to actm-seqr?
 
> > Have also been looking at the possibility of using
> > 
> > (list (list colw (intern rsel) (intern scope)))
> > 
> > Or would this be considered replication? Because the call
> > to intern would happen later anyway.
> 
> Then it would cause the error you reported in your OP.

   (list (list colw (intern rsel) (intern scope)))

The above will be for the interactive part, so that the string values
would be changed immediately to symbols.

And since I now fixed the problem by checking with stringp so intern gets
called when calling the function programatically with strings.