Each major mode should have a normal @dfn{mode hook} named
@code{@var{modename}-mode-hook}. The very last thing the major mode command
should do is to call @code{run-mode-hooks}. This runs the normal
-hook @code{change-major-mode-after-body-hook}, the mode hook,
+hook @code{change-major-mode-after-body-hook}, the mode hook, the
+function @code{hack-local-variables} (when the buffer is visiting a file),
and then the normal hook @code{after-change-major-mode-hook}.
@xref{Mode Hooks}.
It also processes local variables specified in the file text.
@deffn Command normal-mode &optional find-file
-This function establishes the proper major mode and buffer-local variable
-bindings for the current buffer. First it calls @code{set-auto-mode}
-(see below), then it runs @code{hack-local-variables} to parse, and
-bind or evaluate as appropriate, the file's local variables
-(@pxref{File Local Variables}).
+This function establishes the proper major mode and buffer-local
+variable bindings for the current buffer. It calls
+@code{set-auto-mode} (see below). As from Emacs 25.2, it no longer
+runs @code{hack-local-variables}, this now being done in
+@code{run-mode-hooks} at the initialization of major modes
+(@pxref{Mode Hooks}).
If the @var{find-file} argument to @code{normal-mode} is non-@code{nil},
@code{normal-mode} assumes that the @code{find-file} function is calling
@var{find-file} is normally @code{nil}. In this case,
@code{normal-mode} unconditionally processes any file local variables.
-The function calls @code{set-auto-mode} to choose a major mode. If this
-does not specify a mode, the buffer stays in the major mode determined
-by the default value of @code{major-mode} (see below).
+The function calls @code{set-auto-mode} to choose and set a major
+mode. If this does not specify a mode, the buffer stays in the major
+mode determined by the default value of @code{major-mode} (see below).
@cindex file mode specification error
@code{normal-mode} uses @code{condition-case} around the call to the
@defun set-auto-mode &optional keep-mode-if-same
@cindex visited file mode
- This function selects the major mode that is appropriate for the
-current buffer. It bases its decision (in order of precedence) on the
-@w{@samp{-*-}} line, on any @samp{mode:} local variable near the end of
-a file, on the @w{@samp{#!}} line (using @code{interpreter-mode-alist}),
-on the text at the beginning of the buffer (using
-@code{magic-mode-alist}), and finally on the visited file name (using
-@code{auto-mode-alist}). @xref{Choosing Modes, , How Major Modes are
-Chosen, emacs, The GNU Emacs Manual}. If @code{enable-local-variables}
-is @code{nil}, @code{set-auto-mode} does not check the @w{@samp{-*-}}
-line, or near the end of the file, for any mode tag.
+ This function selects and sets the major mode that is appropriate
+for the current buffer. It bases its decision (in order of
+precedence) on the @w{@samp{-*-}} line, on any @samp{mode:} local
+variable near the end of a file, on the @w{@samp{#!}} line (using
+@code{interpreter-mode-alist}), on the text at the beginning of the
+buffer (using @code{magic-mode-alist}), and finally on the visited
+file name (using @code{auto-mode-alist}). @xref{Choosing Modes, , How
+Major Modes are Chosen, emacs, The GNU Emacs Manual}. If
+@code{enable-local-variables} is @code{nil}, @code{set-auto-mode} does
+not check the @w{@samp{-*-}} line, or near the end of the file, for
+any mode tag.
@vindex inhibit-local-variables-regexps
There are some file types where it is not appropriate to scan the file
@item
The new mode has its own mode hook, @code{@var{variant}-hook}. It
runs this hook, after running the hooks of its ancestor modes, with
-@code{run-mode-hooks}, as the last thing it does. @xref{Mode Hooks}.
+@code{run-mode-hooks}, as the last thing it does, apart from running
+any @code{:after-hook} form it may have. @xref{Mode Hooks}.
@end itemize
In addition, you can specify how to override other aspects of
documentation string. If you omit @var{docstring},
@code{define-derived-mode} generates a documentation string.
-The @var{keyword-args} are pairs of keywords and values. The values
-are evaluated. The following keywords are currently supported:
+The @var{keyword-args} are pairs of keywords and values. The values,
+except for @code{:after-hook}'s, are evaluated. The following
+keywords are currently supported:
@table @code
@item :syntax-table
this mode. (Not all major modes have one.) The command
@code{customize-mode} uses this. @code{define-derived-mode} does
@emph{not} automatically define the specified customization group.
+
+@item :after-hook
+This optional keyword specifies a single Lisp form to evaluate as the
+final act of the mode function, after the mode hooks have been run.
+It should not be quoted. Since the form might be evaluated after the
+mode function has terminated, it should not access any element of the
+mode function's local state. An @code{:after-hook} form is useful for
+setting up aspects of the mode which depend on the user's settings,
+which in turn may have been changed in a mode hook.
@end table
Here is a hypothetical example:
@defun run-mode-hooks &rest hookvars
Major modes should run their mode hook using this function. It is
similar to @code{run-hooks} (@pxref{Hooks}), but it also runs
-@code{change-major-mode-after-body-hook} and
-@code{after-change-major-mode-hook}.
+@code{change-major-mode-after-body-hook}, @code{hack-local-variables}
+(when the buffer is visiting a file) (@pxref{File Local Variables}),
+and @code{after-change-major-mode-hook}. The last thing it does is to
+evaluate any @code{:after-hook} forms declared by parent modes
+(@pxref{Derived Modes}).
When this function is called during the execution of a
-@code{delay-mode-hooks} form, it does not run the hooks immediately.
+@code{delay-mode-hooks} form, it does not run the hooks or
+@code{hack-local-variables} or evaluate the forms immediately.
Instead, it arranges for the next call to @code{run-mode-hooks} to run
them.
@end defun