Re: trapping process filter error in a thread

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

Thien-Thi Nguyen wrote:

> I'm in the process of writing a dead-link checker

Good idea ...

> and would like to use Emacs' threads and ‘url-http’ funcs.
> I've run into a problem w/ GNU Emacs 27.1 (Debian), however:
> When there is a TLS problem, i am unable to trap the process
> filter error. It seems ‘condition-case’ is not the right
> tool for the job.
>
> (defun func ()
>   (let ((noninteractive t))
>     (condition-case nil
>         (if (url-http-file-exists-p url)
>             "ok"
>           "dead")
>       (t "error"))))

Isn't the syntax/usage rather as in e.g.

(defun erc-element-next (&optional prev)
  (interactive "P")
  (when (erc-at-prompt-p)
    (goto-char (point-min)) )
  (condition-case nil
      (if prev
          (erc-button-previous)
        (erc-button-next) )
    (error (progn
             (goto-char (point-max))
             (when prev
               (erc-bol) )))))

> (a) Can anyone else reproduce this on their Emacs?
>     (Obviously your Emacs has to be built w/
>     thread support.)

What are threads in this context and how do you build Emacs
for that

> (c) Is there a recommended way to trap process filter errors
>     for a noninteractive (perhaps batch) session?

What's a process filter?

> Thank-you for any insight into this corner of Emacs Lisp!

You don't say ;)

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