Commit 0ade8edb authored by Richard M. Stallman's avatar Richard M. Stallman
Browse files

(Unloading): Document FEATURE-unload-function instead of FEATURE-unload-hook.

parent 39dc0d57
......@@ -862,24 +862,27 @@ library with @code{defun}, @code{defalias}, @code{defsubst},
It then restores any autoloads formerly associated with those symbols.
(Loading saves these in the @code{autoload} property of the symbol.)
@vindex unload-feature-special-hooks
Before restoring the previous definitions, @code{unload-feature} runs
@code{remove-hook} to remove functions in the library from certain
hooks. These hooks include variables whose names end in @samp{hook}
or @samp{-hooks}, plus those listed in
@code{unload-feature-special-hooks}. This is to prevent Emacs from
ceasing to function because important hooks refer to functions that
are no longer defined.
@code{unload-feature-special-hooks}, as well as
@code{auto-mode-alist}. This is to prevent Emacs from ceasing to
function because important hooks refer to functions that are no longer
defined.
@vindex @var{feature}-unload-hook
Standard unloading activities also undoes ELP profiling of functions
in that library, unprovides any features provided by the library, and
cancels timers held in variables defined by the library.
@vindex @var{feature}-unload-function
If these measures are not sufficient to prevent malfunction, a library
can define an explicit unload hook. If @code{@var{feature}-unload-hook}
is defined, it is run as a normal hook before restoring the previous
definitions, @emph{instead of} the usual hook-removing actions. The
unload hook ought to undo all the global state changes made by the
library that might cease to work once the library is unloaded.
@code{unload-feature} can cause problems with libraries that fail to do
this, so it should be used with caution.
can define an explicit unloader named @code{@var{feature}-unload-function}.
If that symbol is defined as a function, @code{unload-feature} calls
it with no arguments before doing anything else. It can do whatever
is appropriate to unload the library. If it returns @code{nil},
@code{unload-feature} proceeds to take the normal unload actions.
Otherwise it considers the job to be done.
Ordinarily, @code{unload-feature} refuses to unload a library on which
other loaded libraries depend. (A library @var{a} depends on library
......
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