Richard Stallman wrote:
I will add this to the documentation of font-lock-add-keywords.
@strong{Warning:} major mode functions must not call
@code{font-lock-add-keywords} under any circumstances, either directly
or indirectly. (This would lead to incorrect behavior for some minor
modes.) They should set up for Font Lock mode by setting
@code{font-lock-keywords}.
Well, it depends on _how_ they call it indirectly. For instance, if
the indirect call adds it to a mode hook everything is fine. I
believe that it is better to apply the patch below to modes.texi.
(I could not reply earlier due to connection problems.)
===File ~/modes.texi-diff===================================
*** modes.texi 29 May 2005 10:42:38 -0500 1.112
--- modes.texi 06 Jun 2005 18:06:28 -0500
***************
*** 2626,2632 ****
You can use @code{font-lock-add-keywords} to add additional
search-based fontification rules to a major mode, and
! @code{font-lock-remove-keywords} to removes rules.
@defun font-lock-add-keywords mode keywords &optional append
This function adds highlighting @var{keywords} for @var{mode}. The
--- 2626,2634 ----
You can use @code{font-lock-add-keywords} to add additional
search-based fontification rules to a major mode, and
! @code{font-lock-remove-keywords} to remove rules. These two functions
! are meant for user customization and for use in minor mode functions.
! Major mode functions should set @code{font-lock-keywords} instead.
@defun font-lock-add-keywords mode keywords &optional append
This function adds highlighting @var{keywords} for @var{mode}. The
***************
*** 2657,2662 ****
--- 2659,2685 ----
@samp{FIXME}, even in comments, and another to fontify the words
@samp{and}, @samp{or} and @samp{not} as keywords.
+ The above example does @emph{not} add the fontification patterns to
+ major modes derived from C mode, as is usually desired. To add them
+ to derived modes too, pass @code{nil} for mode and add the call to
+ @var{mode}'s mode hook.
+
+ For example:
+
+ @smallexample
+ (add-hook 'c-mode-hook
+ (lambda ()
+ (font-lock-add-keywords nil
+ '(("\\<\\(FIXME\\):" 1 font-lock-warning-face prepend)
+ ("\\<\\(and\\|or\\|not\\)\\>" .
+ font-lock-keyword-face)))))
+ @end smallexample
+
+ The above procedure may fail to add keywords to a derived mode if
+ @var{mode} or the derived mode do not yet follow the standard
+ conventions. File a bug report if this happens, so that the offending
+ major mode can be corrected.
+
Some modes have specialized support for additional patterns. See the
variables @code{c-font-lock-extra-types},
@code{c++-font-lock-extra-types}, @code{objc-font-lock-extra-types}
***************
*** 2668,2682 ****
in @code{font-lock-add-keywords}, @var{mode} should be a major mode
command name or @code{nil}. If @code{nil}, the highlighting
@var{keywords} are immediately removed in the current buffer.
- @end defun
! @strong{Warning:} Only use a [EMAIL PROTECTED] @var{mode} argument when
! you use @code{font-lock-add-keywords} or
! @code{font-lock-remove-keywords} in your @file{.emacs} file. When you
! use these functions from a Lisp program (such as a minor mode), we
! recommend that you use @code{nil} for @var{mode} (and place the call
! on a hook) to avoid subtle problems due to the details of the
! implementation.
@node Other Font Lock Variables
@subsection Other Font Lock Variables
--- 2691,2704 ----
in @code{font-lock-add-keywords}, @var{mode} should be a major mode
command name or @code{nil}. If @code{nil}, the highlighting
@var{keywords} are immediately removed in the current buffer.
! This function does @emph{not} remove the highlighting @var{keywords}
! from derived modes, as is usually desired. To remove them from
! derived modes too, pass @code{nil} for mode and add the call to
! @var{mode}'s hook. This may fail if @var{mode} or a derived mode do
! not yet follow the standard conventions. File a bug report if this
! happens, so that the offending major mode can be corrected.
! @end defun
@node Other Font Lock Variables
@subsection Other Font Lock Variables
============================================================
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