Andy Wingo <wingo@igalia.com> skribis:

> So then, for example, the elogind service would indicate that it
> installs udev rules, dbus interfaces, and polkit rules from the elogind
> package.  The udev service would then query all services, adding rules
> from services that indicate that they extend the udev configuration.  To
> do this I propose a "finalize-configuration" field in services.  First,
> the services are collected into a list, as they are now.  Next, Guix
> does something like this:
>
>   (define (finalize-services services)
>     (map (lambda (service)
>            ((service-finalize service) service services))
>          services))
>
> The default service-finalize will be (lambda (service services)
> service).  WDYT?

Yes, something like that.

An important characteristic is that service types extend each other:
dbus extends dmd (by adding stuff into dmd.conf), polkit extends dbus
(through .service files), elogind extends polkit (through policy files)
and dbus and udev, and so on.

Service types and their “extends” relations form a DAG like this: