Re: org-mode and mode hooks.

[Luc Teirlinck <teirllm@dms.auburn.edu>]

Stefan Monnier wrote:

   Actually, don't worry too mucvh about that, because I think that even with
   the current code things don't work right unless the major mode follows
   the conventions w.r.t major-mode-derivation.

My changes do not introduce new problems, they fix problems with the
current code.  The problem is that the fix is not perfect.  It limits
the situations in which problems occur and makes the consequences less
severe if they occur.

With the current code problems are _much_ more likely to happen than
with my proposed changes.  For instance with the current code,
enabling Font Lock mode in a major mode body, like for instance
sql-interactive-mode does, will cause problems for derived modes, no
matter how well the major mode conventions are followed.  The fact
that sql-interactive-mode later disables Font Lock again does not
correct this.  Also the consequences are much more severe with the
current code.  With the current code, Font Lock may get set up for the
wrong major mode, giving completely incorrect fontification.  After my
changes, there is the slight probability of loosing a few keywords for
major modes that do not follow the conventions.

I believe that it is possible to implement things completely reliably
by letting major modes specify a list of major modes from which they
want to inherit keywords and using a non-nil MODE argument.  But that
would require more extensive changes to Font Lock and would also
require some (much less extensive) changes to define-derived-mode.  I
believe that a nil argument for MODE has been around for a while so
for backward compatibility, one would still need to reasonably take
care of such calls.  The question is whether the remaining problems
are worth the trouble.

Sincerely,

Luc.