Re: How to handle required plugins and dbus services for GNOME Programs?

[Federico Beffa <beffa@ieee.org>]

On Tue, Jun 30, 2015 at 6:01 PM, Mark H Weaver <mhw@netris.org> wrote:
> Federico Beffa <beffa@ieee.org> writes:
>
>> On Mon, Jun 29, 2015 at 1:35 PM, Ludovic Courtès <ludo@gnu.org> wrote:
>>> Then, should we make dconf an implicit input of
>>> glib-or-gtk-build-system?
>>>
>>> Or should we add it as an explicit dependency on a case-by-case basis?
>>
>> IMO, given that every GLib based program needs it, the right thing to
>> do is to make it an implicit input of 'glib-or-gtk-build-system'.
>
> Many GLib based programs do *not* need dconf.  So far, I know of only
> two programs in Guix that need dconf.  It is a GNOME thing, not a GLib
> thing.

You are right. I got confused. 'dconf' is a backend of 'GSettings'.

>
> Also, I wouldn't be surprised if one of the transitive inputs of dconf
> uses 'glib-or-gtk-build-system', which would lead to a circularity
> problem.
>
>> In a similar way, every GLib based program/library makes use of sound
>> themes.
>
> That's not true either.
>
> It may be that we should have a 'gnome-build-system' that's based on
> 'glib-or-gtk-build-system' but adds these extra implicit inputs and
> arranges for more environment variables to be set in the wrappers.

The distinction between "a GNOME application" and an application
making use of "a subset of the GNOME infrastructure and requiring
'dconf' and/or 'libcanberra'" doesn't appear to be clear cut to me:

* GLib is hosted on the GNOME site. Isn't it part of the GNOME project?
* I get the warnings:

    Gtk-Message: Failed to load module "canberra-gtk-module"
    GLib-GIO-Message: Using the 'memory' GSettings backend.  Your
settings will not be saved or shared with other     applications.

  even when starting 'emacs' and the first one even when importing
'matplotlib' inside of a python shell. As far as I know, these two
programs are not part of GNOME.

Adding 'dconf' and 'libcanberra' as default inputs to
'glib-or-gtk-build-system' would make many of these problems go away,
with the only drawback of a possibly unused entry in an environment
variable. However, if you want to be super accurate then yes, this
will not do.

Fede