Re: gnus-extra-headers

[Eric Abrahamsen <eric@ericabrahamsen.net>]

Colin Baxter <m43cap@yandex.com> writes:

>>>>>> Eric Abrahamsen <eric@ericabrahamsen.net> writes:
>
>     > Colin Baxter <m43cap@yandex.com> writes:
>     >> Hello Eric,
>     >>>>>>> Eric Abrahamsen <eric@ericabrahamsen.net> writes:
>     >> 
>     >> > Colin Baxter <m43cap@yandex.com> writes: >> Hello,
>     >> >> 
>     >> >> If emacs (tested with 27.2 and 28.0.50) is launched with -Q
>     >> (or >> gnus-extra-headers has not been set explicitly by the
>     >> user) then >> the variable gnus-extra-headers has the value:
>     >> >> 
>     >> >> gnus-extra-headers is a variable defined in ‘gnus-sum.el’.
>     >> Its >> value is (X-Diary-Time-Zone X-Diary-Dow X-Diary-Year >>
>     >> X-Diary-Month X-Diary-Dom X-Diary-Hour X-Diary-Minute To Cc >>
>     >> Keywords Gcc Newsgroups X-GM-LABELS) Original value was (To Cc >>
>     >> Keywords Gcc Newsgroups X-GM-LABELS)
>     >> >> 
>     >> >> You can customize this variable.
>     >> >> 
>     >> >> 
>     >> >> This variable was introduced, or its default value was
>     >> changed, >> in version 25.1 of Emacs.
>     >> >> 
>     >> >> Documentation: Extra headers to parse.
>     >> >> 
>     >> >> The X-Diary settings seem to come from nndiary.el, but there
>     >> is >> nothing in the doc-string to indicate this.
>     >> >> 
>     >> >> Is this a bug? Is not the "Original value" of
>     >> gnus-extra-headers >> incorrect?
>     >> 
>     >> > I don't think it's really a bug. If you don't use the nndiary >
>     >> backend, those headers don't get added to `gnus-extra-headers', >
>     >> and it has its "original value" as noted in *Help*. I don't think
>     >> > there's any contract that says additional libraries can't >
>     >> manipulate the value of customization options... is there?
>     >> 
>     >> True, but the user might suppose that using -Q ensures that no
>     >> extra libraries are loaded. I would have thought that nndiary
>     >> constitutes an extra library. If it does not and the library is
>     >> germane to -Q then why omit any mention of it from
>     >> gnus-extra-headers? I have quickly looked at NEWS for emacs-25.1
>     >> but found nothing relevant.
>
>     > If I start with "emacs -Q" and a minimal Gnus setup, the nndiary
>     > isn't loaded and its values aren't added to
>     > `gnus-extra-headers'. The odd thing is that in my usual Emacs/Gnus
>     > set up, those values _are_ added, and I don't use nndiary or
>     > gnus-diary.el. Hang on, let me force an error in there and see
>     > exactly what's loading it.
>
>     > Nope, I just restarted Emacs and Gnus, and did some other
>     > Org/Diary/Calendar stuff for good measure, and now nothing has
>     > triggered a load of 'nndiary, and the extra values aren't added.
>
>     > Obviously something, somewhere, eventually triggers that load in
>     > my setup, but it doesn't seem to happen by default. I'm quite
>     > ready to believe that something is loading 'nndiary when it
>     > doesn't need to, but so far I don't know what it is.
>
>     > Maybe you could give it a shot? Delete nndiary.elc, stick a call
>     > to (error) in nndiary.el,
>
> How do I modify the file nndiary.el to achieve this?

Sorry, I didn't ask how you're using Emacs, and assumed you were running
from the source tree, or had access to it. If you do have access to
nndiary.el, just edit it regularly in Emacs, and add a line like:

(error)

anywhere in the file, maybe at the top. You'll need to remove
nndiary.elc, otherwise that will get loaded instead of the *el file.

>     > and restart everything?
>
> What I do know is that if nndiary is not present (.el) and (.elc) then
> gnus-extra-headers becomes (To Cc Keywords Gcc Newsgroups X-GM-LABELS).

If those files aren't present, I guess I would have expected you to see
an error, as whatever is loading it fails to find it.