Summary format - the `u' spec

Summary format - the `u' spec

[Harry Putnam]

The following message is a courtesy copy of an article
that has been posted to gnu.emacs.gnus as well.


>From gnus info; this looks like it can be made to do what I want.

`u'
     User defined specifier.  The next character in the format string
     should be a letter.  Gnus will call the function
     `gnus-user-format-function-'`X', where `X' is the letter following
     `%u'.  The function will be passed the current header as argument.
     The function should return a string, which will be inserted into
     the summary just like information from any other summary specifier.


Hopefully I'm, correct in thinking the line that says:
"...The function will be passed the current header as argument."
Means that all header lines get scanned.

I want to use this option to cause gnus to scan the headers for 
this pattern `^Keywords: \\[A\\] '.  And if found, to insert the capital
letter found inside the [] into th summary display. 

I think this is fairly simple, maybe but don't really have a clue how
to proceed.

Does someone have an example of using this function in the way I
described?

Re: Summary format - the `u' spec

[Kai Großjohann]

On 04 Mar 2001, Harry Putnam wrote:

> Hopefully I'm, correct in thinking the line that says:
> "...The function will be passed the current header as argument."
> Means that all header lines get scanned.

Hm, no, not really.  `Mail header' in this context (oh, how I love the
inconsistent terminology in Gnus!) is a structure which contains the
information from the NOV (or overview) file/data in a Lisp-predigested
form.  For example, if X is such a header, then (mail-header-subject
X) returns a string, the subject of the message.

Such a header contains only those bits of information that are present
in the overview file.  For nnml, you can put more information into the
overview file using the variables gnus-extra-headers and
nnmail-extra-headers.  Not sure if this works with NNTP (news) servers.

> I want to use this option to cause gnus to scan the headers for this
> pattern `^Keywords: \\[A\\] '.  And if found, to insert the capital
> letter found inside the [] into th summary display.

Ah.  Yes.  Hm.  What you want is to

    (add-to-list 'nnmail-extra-headers 'Keywords)
    (add-to-list 'gnus-extra-headers 'Keywords)

And then you can do:

    (defun gnus-user-format-function-H (header)
      (let* ((xtra (mail-header-extra header))
             (kw (cdr (assq 'Keywords xtra))))
        (if (and kw (stringp kw))
            (substring kw 0 5)
          "    ")))

This is untested.  Not sure if it works.  It tries to print the first
5 or 6 characters of the Keywords header, or spaces (if there is no
Keywords header).

Does this work, and can you take it from here?

kai
-- 
Be indiscrete.  Do it continuously.

Re: Summary format - the `u' spec

[Harry Putnam]

Kai.Grossjohann@CS.Uni-Dortmund.DE (Kai Großjohann) writes:

> On 04 Mar 2001, Harry Putnam wrote:
> 
> > Hopefully I'm, correct in thinking the line that says:
> > "...The function will be passed the current header as argument."
> > Means that all header lines get scanned.
> 
> Hm, no, not really.  `Mail header' in this context (oh, how I love the
> inconsistent terminology in Gnus!) is a structure which contains the
> information from the NOV (or overview) file/data in a Lisp-predigested
> form.  For example, if X is such a header, then (mail-header-subject
> X) returns a string, the subject of the message.

Well, still close enough to get what I want here.  I do understand the
NOV file a bit and as luck would have it I've had code in .gnus for a
long time to insert a `Keywords' header into the .overiew file. And
have them displayed in the article view buffer.

[...]

> > I want to use this option to cause gnus to scan the headers for this
> > pattern `^Keywords: \\[A\\] '.  And if found, to insert the capital
> > letter found inside the [] into th summary display.

[...]

> And then you can do:
> 
>     (defun gnus-user-format-function-H (header)
>       (let* ((xtra (mail-header-extra header))
>              (kw (cdr (assq 'Keywords xtra))))
>         (if (and kw (stringp kw))
>             (substring kw 0 5)
>           "    ")))
> 
> This is untested.  Not sure if it works.  It tries to print the first
> 5 or 6 characters of the Keywords header, or spaces (if there is no
> Keywords header).
> 
> Does this work, and can you take it from here?

Yes it works, and I see how it works and how to adjust what gets
printed, at least somewhat.  I don't really follow all the ins and
outs of even this simple  code.  But I see that this:

    (defun gnus-user-format-function-H (header)
      (let* ((xtra (mail-header-extra header))
             (kw (cdr (assq 'Keywords xtra))))
        (if (and kw (stringp kw))
            (substring kw 4 5)
          "N")))

Given a keywords header like:
        Keywords: [ed]A something

And a format string like:
        "%2t%U%R%7d%z%I%(%[%uH%4L: %-20,20f%]%) %s\n" 
              (inserted =>)^^^

will give a summary buffer line like:
  (Printing an `N' if no keyword line)

1R  07-Oct [A 161: me                  ] [ed]V [comp.editors] Vim - append to file
inserted => ^^

I guess what I really want to know is if it can be made to match a
regexp instead of a a static number of characters in a string.  And to
return that portion that matches or even better to edit the portion
that matches in some predictable way.

I see the first stringmatch thing is to match the keyword line itself
and I need that, and even bettter your trial code does do that
admirably.

Once we have a match, then the code looks as if it grabs a
predetermined number of characters from the Keyword header begining
with the first character after `:' (0 5).

And I do see how one would adjust that number, if need be.

I guess what I want is, once the keyword is matched, to take the
string after `:' and pluck a pattern from it leaving the rest behind.

Something like what one would do with sed (in bash) in this fashion.

        echo "Keywords: [A] blabbity blah blick"\
        |sed 's/^\(Keywords: \[\)\(A\)\(\]\).*/\2/'
        A
Plucking out only the `A' 

Or with awk
        echo "Keywords: [A] blabbity blah blick"\
        |awk -vRS="\\\[A\\\]" '{gsub (/\[|\]/,"",RT);print RT;ORS=FS}'          
        A

So once the keywords line is matched does elisp offer a pattern
matching command that returns the matched portion?

Re: Summary format - the `u' spec

[Alex Schroeder]

Harry Putnam <reader@newsguy.com> writes:

> So once the keywords line is matched does elisp offer a pattern
> matching command that returns the matched portion?

Hm, you can probably use normal elisp to do it:

(if (string-match "\\[\\([A-Z]\\)\\]" some-string)
    (match-string 0)
  " ")

Or something like that.

Alex.
-- 
http://www.geocities.com/kensanata/
"Your .emacs is either in C:\ or in the directory of %HOME% under Win32."

Re: Summary format - the `u' spec

[Harry Putnam]

Alex Schroeder <alex@gnu.org> writes:

> Harry Putnam <reader@newsguy.com> writes:
> 
> > So once the keywords line is matched does elisp offer a pattern
> > matching command that returns the matched portion?
> 
> Hm, you can probably use normal elisp to do it:
> 
> (if (string-match "\\[\\([A-Z]\\)\\]" some-string)
>     (match-string 0)
>   " ")
> 
> Or something like that.

OK, but revealing the bottomless depths of my lisp ignorance:
How does this fit into the rest of the function?

I tried just splicing it in there a couple ways but of course that
ain't going to fly.

(defun gnus-user-format-function-H (header)
      (let* ((xtra (mail-header-extra header))
             (kw (cdr (assq 'Keywords xtra))))
        (if (and kw (stringp kw)
                (if (string-match "\\[\\([A-Z]\\)\\]" some-string)
        		(match-string 0)
        	      " ")))))


(defun gnus-user-format-function-H (header)
      (let* ((xtra (mail-header-extra header))
             (kw (cdr (assq 'Keywords xtra))))
        (if (and kw (stringp kw))
	    (string-match "\\[\\([A-Z]\\)\\]" some-string)
		(match-string 0)
	      " ")))

NOT!

Re: Summary format - the `u' spec

[Alex Schroeder]

Harry Putnam <reader@newsguy.com> writes:

> (defun gnus-user-format-function-H (header)
>       (let* ((xtra (mail-header-extra header))
>              (kw (cdr (assq 'Keywords xtra))))
>         (if (and kw (stringp kw)
>                 (if (string-match "\\[\\([A-Z]\\)\\]" some-string)
>         		(match-string 0)
>         	      " ")))))

How about this (untested):

(defun gnus-user-format-function-H (header)
  (let* ((xtra (mail-header-extra header))
	 (kw (cdr (assq 'Keywords xtra))))
    (if (and (stringp kw)
	     (string-match "\\[\\([A-Z]\\)\\]" kw))
	(match-string 1 kw)
      " ")))

This assumes kw gets set correctly, I have never done this
mail-header-extra stuff, so you're on your own.  :)

Alex.
-- 
http://www.geocities.com/kensanata/
"Emacs 21 will be out when it comes out.  No beta available."

Re: Summary format - the `u' spec

[Harry Putnam]

Alex Schroeder <alex@gnu.org> writes:

> How about this (untested):
> 
> (defun gnus-user-format-function-H (header)
>   (let* ((xtra (mail-header-extra header))
> 	 (kw (cdr (assq 'Keywords xtra))))
>     (if (and (stringp kw)
> 	     (string-match "\\[\\([A-Z]\\)\\]" kw))
> 	(match-string 1 kw)
>       " ")))
> 
> This assumes kw gets set correctly, I have never done this
> mail-header-extra stuff, so you're on your own.  :)

Haa... right out of the box this baby works.

Thanks Alex

Re: Summary format - the `u' spec

[Kai Großjohann]

On 05 Mar 2001, Alex Schroeder wrote:

> (if (string-match "\\[\\([A-Z]\\)\\]" some-string)
>     (match-string 0)
>   " ")

That should be (match-string 0 some-string).  Or maybe (match-string 1
some-string), since Harry wants the stuff _inside_ the square brackets.

kai
-- 
Be indiscrete.  Do it continuously.

Re: Summary format - the `u' spec

[Pavel Janík ml.]

   From: Harry Putnam <reader@newsguy.com>
   Date: 04 Mar 2001 08:21:59 -0800

Hi Harry,

   > I want to use this option to cause gnus to scan the headers for 
   > this pattern `^Keywords: \\[A\\] '.  And if found, to insert the capital
   > letter found inside the [] into th summary display. 
   > 
   > I think this is fairly simple, maybe but don't really have a clue how
   > to proceed.
   > 
   > Does someone have an example of using this function in the way I
   > described?

yes. I use something similar. This is workaround for tags which rmail can
do and gnus can not (it is already in the wish list). If the mail has
X-Annotations: header, the rest of the line is displayed in the summary:

(setq gnus-extra-headers '(To Cc X-Annotations))
(setq nnmail-extra-headers gnus-extra-headers)

(defun gnus-user-format-function-X (header)
  "My user-defined function for annotations."
  (let ((my-extra-headers (mail-header-extra gnus-tmp-header)))
    ; Search for X-Annotations
    (while (and my-extra-headers (not (eq (car (car my-extra-headers)) 'X-Annotations)))
      (setq my-extra-headers (cdr my-extra-headers)))
    (setq my-extra-headers (cdr (car my-extra-headers)))
    (if my-extra-headers
        (concat "{" (rfc2047-decode-string my-extra-headers) "} ")
      "")))

Tested, I use it almost everyday.

Hmm, isn't this the time where we should implement this? There are at least
three people who want it :-)
-- 
Pavel Janík ml.
Pavel@Janik.cz
http://www.janik.cz