bug#19392: Emacs searches for dabbrevs in archive buffers

[Eli Zaretskii]

> From: Stefan Kangas <stefan@marxist.se>
> Date: Fri, 22 Oct 2021 19:43:18 -0400
> Cc: Eli Zaretskii <eliz@gnu.org>, pogonyshev@gmail.com, 19392@debbugs.gnu.org
> 
> Lars Ingebrigtsen <larsi@gnus.org> writes:
> 
> > Eli Zaretskii <eliz@gnu.org> writes:
> >
> >>> We do have all of that, but I think that it would be reasonable (by
> >>> default) for `dabbrev--select-buffers' to ignore these "binary"
> >>> buffers.  Because the data there is mostly noise.
> >>
> >> If you want to do that, why not just add the appropriate regexp(s) to
> >> dabbrev-ignored-buffer-regexps?
> >
> > It's a user option, so we shouldn't add things to it dynamically, but we
> > could add a default that excludes these files.  The problem is, though,
> > that that would be a very complex regexp matching everything that
> > arc/tar/image modes covers, which is quite a lot.
> >
> > The user option thing also goes for `dabbrev-ignored-buffer-names'.
> 
> Shouldn't we rather have a defcustom to ignore certain major modes?
> The name could be `dabbrev-ignored-major-modes'.

I don't necessarily object, but don't the existing defcustom's already
cover that, via buffer names?  We shouldn't over-engineer this, I
think.