Re: Exiting from mapc

[Jean Louis <bugs@gnu.support>]

* Heime via Users list for the GNU Emacs text editor <help-gnu-emacs@gnu.org> [2024-12-31 22:37]:
> 
> How can I exit when encountering 'safg or 'nogo 
> 
> (defun amazones-falkotr-kntlr (actm-seqr)
> 
>   (mapc
> 
>     (lambda (actm)
>       ;; Evaluate conditions and executes corresponding actions
>       ;; based on matching clauses.
> 
>       (cond
> 
>         ;; CASE
>         ((eq actm 'safg)
>            (message "SAFG amazones-falkotr-kntlr"))

To answer the message "How can I exit when encountering 'safg or
'nogo', yes, you can exit.

Here is what happens if there is no number 1 in the list here below:

(let ((list (catch 'no-go
  (mapc (lambda (item)
          (if (= item 1)
              (throw 'no-go nil)
            (message "Processing item: %S" item)))
        '(2 3 4 5 6)))))
list)  ➜ (2 3 4 5 6)

But if there is number one, `throw' exits:

(let ((list (catch 'no-go
  (mapc (lambda (item)
          (if (= item 1)
              (throw 'no-go nil)
            (message "Processing item: %S" item)))
        '(2 1 3 4 5 6)))))
list)
Processing item: 2
and finished there!

So yes, you can exit from mapc if you enclose it with `catch' this way.

-- 
Jean Louis