Need help writing predicate function

Need help writing predicate function

[Max Evans]

Help, gnus!

I'm trying to write a simple predicate function to use in my
posting-styles, since from my reading of the manual you can't match
two things at once otherwise, which is what I want to do.

I'm trying to make a rule that kicks in only when a certain company
sends me an email AND when it's sent to a particular address. It's
only relevant when I'm replying back to them, though.

Here's what I've got so far:

(defun max-gnus-predicate ()
  (when (eq major-mode 'gnus-article-mode)
    (and (string-match "foo@bar.org" (with-current-buffer gnus-article-buffer
				       (message-fetch-field "from")))
	 (string-match "visitantar+alias@protonmail.com" (with-current-buffer gnus-article-buffer
							   (message-fetch-field "to"))))))
						 
The problem I'm running into is that the function fails if the
*Article* buffer ever gets killed. When that happens, it corrupts the
mail header. Which makes sense with how I've written it.

I'm sure there's a smarter way of doing what I want to do, so would
someone mind helping me out?

(Please keep me in the thread. I'm not subscribed.)

-Max

Re: Need help writing predicate function

[Eric S Fraga]

You might want to look at what gnus does.  In particular, it copies the
article buffer first using gnus-copy-article-buffer (in gnus-msg.el)
before considering the styles.  That copy of the article buffer should
be accessible in your max-gnus-predicate function... if I understand the
gnus code correctly which is a big *if*.

-- 
Eric S Fraga via gnus (Emacs 30.0.50 2023-09-14) on Debian 12.2

Re: Need help writing predicate function

[Bob Newell]

I do something similar to change identity and/or input
language based on addressee.  I just put it in a hook
  
(add-hook 'message-setup-hook 'rjn-change-stuff-by-addressee t)

and that works for me; the appropriate identity gets chosen
via gnus-alias-use-identity when the message reply is set up.

My complete code is this.  It is not the same as you ask but
easily modified.  You'd only need the upper half.

(defun rjn-change-stuff-by-addressee ()
  (interactive)
  (let ((addressee (message-fetch-field "To"))
	netaddr person smtppref)
    (if addressee
        (setq netaddr (cadr (mail-extract-address-components addressee))))
    (if netaddr
          (setq person (car (bbdb-search (bbdb-records) :mail netaddr))))
    (if person
        (setq smtppref (bbdb-record-field person 'smtp)))
    (if smtppref
	   (gnus-alias-use-identity smtppref))
    	      ) 

  (let ((addressee (message-fetch-field "To"))
	netaddr person langpref)
    (if addressee
        (setq netaddr (cadr (mail-extract-address-components addressee))))
    (if netaddr
	(progn
          (setq person (car (bbdb-search (bbdb-records) :mail netaddr)))))
	    (if person
		(setq langpref (bbdb-record-field person 'language)))
    (if langpref
	(set-input-method langpref)))
  )

-- 
Bob Newell
Honolulu, Hawai`i

- Via GNU/Linux/Emacs/Gnus/BBDB