bug#63620: 30.0.50; [Feature Request] run hooks on sleep/wake

[Michael Albinus <michael.albinus@gmx.de>]

Andrew Cohen <acohen@ust.hk> writes:

Hi Andrew,

> 2. Add a small package dbus-sleep.el. I would also remove gnus-dbus.el
> but leave the variable 'gnus-dbus-close-on-sleep and use it to control
> the installation of appropriate gnus functions to the new hooks.
>
> 3. Add the new code to the existing dbus.el. I would also remove
> gnus-dbus.el but leave the variable 'gnus-dbus-close-on-sleep and use it
> to control the installation of appropriate functions to the new hooks.
>
> I mostly favor adding it to dbus.el. The argument against: dbus.el is
> focused on providing language bindings for the D-Bus API rather than a
> user-feature. The removal of gnus-dbus.el shouldn't cause any problem
> since I would maintain the same functionality enabled by the same
> variable, so no user-visible change.

Using D-Bus is just an implementation detail. What you want are
handlers, which are invoked when your laptop falls asleep or awakes.

A general package could implement it using D-Bus if available, or using
something else if there's no D-Bus. See battery.el, which uses the D-Bus
service "org.freedesktop.UPower" only if possible. Your package might be
called sleep.el or alike.

Your code uses the D-Bus service "org.freedesktop.login1", which isn't
part of the basic D-Bus spec. So it isn't suited for dbus.el anyway.

> ;;;###autoload
> (defun dbus-sleep-enable ()
>   "Use `dbus-register-signal' to close servers on sleep."
>   (interactive)

I would make it rather a global minor mode, that you can enable/disable
it easily.

>   ;; Don't enable if it's already enabled.
>   (when (and (featurep 'dbusbind) (not dbus-sleep-registration-object))

Perhaps, you check also for the service "org.freedesktop.login1", like

--8<---------------cut here---------------start------------->8---
(member "org.freedesktop.login1" (dbus-list-activatable-names :system))
--8<---------------cut here---------------end--------------->8---

This check might return nil for several reasons, like the system bus is
not running, or you don't have permissions to speak to the system bus,
or the service simply doesn't exist.

Best regards, Michael.