Suggestion: tell `gnus-part-display-hook'-functions whether header/body

[Christoph Conrad <christoph.conrad@gmx.de>]

Hi,

******* Motivation

I wanted to add a function which washes message/news which of
content-type "text/html". I saw that a function
`gnus-article-wash-html' (on "W h" in summary) does this and the
manual states that it

    Treat HTML (`gnus-article-wash-html'). Note that the this is
    USUALLY DONE AUTOMATICALLY by Gnus if the message in question has
    a `Content-Type' header that says that this type has been done.

(emphasizing by me)

But:

1) It uses w3. This is too slow for me (P133), i wanted to use lynx as
   with multipart messages (displaying the html part)
2) It doesn't work for me (any hint?)

******* Solution

So i searched around and found that `gnus-part-display-hook' seems to
be ideal for that task, cause the manual mentions:

    You can, of course, write your own functions to be called from
    `gnus-part-display-hook'. The functions are called narrowed to the
    part, and you can do anything you like, pretty much.

******* Problem

But one problem remains:

The functions in `gnus-part-display-hook' are called TWICE.

call chain:

gnus-article-prepare-display -> gnus-display-mime-function
(gnus-display-mime) ->gnus-treat-article (1x body, 1x header)

But there's no guaranted mechanism to distinguish whether we are
called with the article narrowd to the body or to the headers.

There are some possibilities:

Body part when:

;;      (let* ( (buffer-read-only nil)
;;              (ct  (message-fetch-field "content-type"))
;;              (ctg (gnus-fetch-field    "content-type")) )
;;        ;; ct is nil when in body part
;;        (when (and (null ct)
;;                   ctg
;;                   (string-match "^text/html" ctg))

or

;;      (let* ( (buffer-read-only nil)
;;              (content-type (gnus-fetch-field "content-type")) )
;;        ;; condition == 'head when in head / nil in body
;;        (when (and (null condition)
;;                   content-type
;;                   (string-match "^text/html" content-type))

The second "solution" relies on variables which are defined from the
function calling the functions in `gnus-part-display-hook'.

******* Question

So i ask for defining a guranteed way of knowing whether in header or
body when called in `gnus-part-display-hook'. A good way could to not
run the hook with `run-hooks' but with `run-hook-with-args' and to
deliver one arg (a list) saying whether we are in header or body part.
I see, this would break compatibility.

Another solution could be to define a variable which is guaranteed to
be defined when in functions in `gnus-part-display-hook'.

The best way would be to extend the built-in mechanism for
"gnus-treat-*"-variables for userdefined functions. (see node
"Customizing Articles" in gnus manual).

Best regards,
cu, -cc-
-- 
=> GNU Emacs Webring @ <http://www.gnusoftware.com/WebRing/> <=
Look Ma, this man can twist his fingers as if they were made of rubber,
isn't that amazing? -- Not really, he's been using emacs for years...!