services: xorg: Deprecate 'screen-locker-service' procedure.

* doc/guix.texi (X Window): Replace 'screen-locker-service' with 'screen-locker-service-type'.
Document <screen-locker-configuration>.
* gnu/services/desktop.scm (desktop-services-for-system): Use screen-locker-service-type.
* gnu/services/xorg.scm: Export accessors for <screen-locker-configuration>.
(<screen-locker>): Rename to ...
(<screen-locker-configuration>): ... this.
(<screen-locker-configuration>)[empty?]: Rename to ...
(<screen-locker-configuration>)[allow-empty-password?]: ... this.
(screen-locker-pam-services): Update record name.
(screen-locker-setuid-programs): Update accessor name.
(screen-locker-service): Deprecate procedure.

Signed-off-by: Ludovic Courtès <ludo@gnu.org>

doc/guix.texi

@@ -22212,18 +22212,38 @@ Usually the X server is started by a login manager.
 @end deffn
 
 
-@deffn {Scheme Procedure} screen-locker-service @var{package} [@var{program}]
+@defvar screen-locker-service-type
-Add @var{package}, a package for a screen locker or screen saver whose
+Type for a service that adds a package for a screen locker or screen
-command is @var{program}, to the set of setuid programs and add a PAM entry
+saver to the set of setuid programs and add a PAM entry for it.  The
-for it.  For example:
+value for this service is a @code{<screen-locker-configuration>} object.
+
+For example, to make XlockMore usable:
 
 @lisp
-(screen-locker-service xlockmore "xlock")
+(service screen-locker-service-type
+         (screen-locker-configuration
+           "xlock" (file-append xlockmore "/bin/xlock") #f))
 @end lisp
 
 makes the good ol' XlockMore usable.
-@end deffn
+@end defvar
 
+@deftp {Data Type} screen-locker-configuration
+Data type representing the configuration of
+@code{screen-locker-service-type}.
+
+@table @asis
+@item @code{name} (type: string)
+Name of the screen locker.
+
+@item @code{program} (type: gexp)
+Path to the executable for the screen locker as a G-Expression.
+
+@item @code{allow-empty-password?} (type: boolean)
+Whether to allow empty passwords.
+
+@end table
+@end deftp
 
 @node Printing Services
 @subsection Printing Services

gnu/services/desktop.scm

@@ -1832,8 +1832,12 @@ (define* (desktop-services-for-system #:optional
              (service sddm-service-type))
 
          ;; Screen lockers are a pretty useful thing and these are small.
-         (screen-locker-service slock)
+         (service screen-locker-service-type
-         (screen-locker-service xlockmore "xlock")
+                  (screen-locker-configuration
+                   "slock" (file-append slock "/bin/slock") #f))
+         (service screen-locker-service-type
+                  (screen-locker-configuration
+                   "xlock" (file-append xlockmore "/bin/xlock") #f))
 
          ;; Add udev rules for MTP devices so that non-root users can access
          ;; them.

gnu/services/xorg.scm

@@ -107,10 +107,13 @@ (define-module (gnu services xorg)
 
             slim-service-type
 
-            screen-locker
+            screen-locker-configuration
-            screen-locker?
+            screen-locker-configuration?
+            screen-locker-configuration-name
+            screen-locker-configuration-program
+            screen-locker-configuration-allow-empty-password?
             screen-locker-service-type
-            screen-locker-service
+            screen-locker-service  ; deprecated
 
             localed-configuration
             localed-configuration?
@@ -683,21 +686,30 @@ (define slim-service-type
 ;;; Screen lockers & co.
 ;;;
 
-(define-record-type <screen-locker>
+(define-record-type <screen-locker-configuration>
-  (screen-locker name program empty?)
+  (screen-locker-configuration name program allow-empty-password?)
+  screen-locker-configuration?
+  (name    screen-locker-configuration-name)           ;string
+  (program screen-locker-configuration-program)        ;gexp
+  (allow-empty-password?
+   screen-locker-configuration-allow-empty-password?)) ;Boolean
+
+(define-deprecated/public-alias
+  screen-locker
+  screen-locker-configuration)
+
+(define-deprecated/public-alias
   screen-locker?
-  (name    screen-locker-name)                     ;string
+  screen-locker-configuration?)
-  (program screen-locker-program)                  ;gexp
-  (empty?  screen-locker-allows-empty-passwords?)) ;Boolean
 
 (define screen-locker-pam-services
   (match-lambda
-    (($ <screen-locker> name _ empty?)
+    (($ <screen-locker-configuration> name _ empty?)
      (list (unix-pam-service name
                              #:allow-empty-passwords? empty?)))))
 
 (define screen-locker-setuid-programs
-  (compose list file-like->setuid-program screen-locker-program))
+  (compose list file-like->setuid-program screen-locker-configuration-program))
 
 (define screen-locker-service-type
   (service-type (name 'screen-locker)
@@ -711,10 +723,11 @@ (define screen-locker-service-type
 the graphical server by making it setuid-root, so it can authenticate users,
 and by creating a PAM service for it.")))
 
-(define* (screen-locker-service package
+(define-deprecated (screen-locker-service package
                                           #:optional
                                           (program (package-name package))
                                           #:key allow-empty-passwords?)
+  screen-locker-service-type
   "Add @var{package}, a package for a screen locker or screen saver whose
 command is @var{program}, to the set of setuid programs and add a PAM entry
 for it.  For example:
@@ -725,7 +738,7 @@ (define* (screen-locker-service package
 
 makes the good ol' XlockMore usable."
   (service screen-locker-service-type
-           (screen-locker program
+           (screen-locker-configuration program
                                         (file-append package "/bin/" program)
                                         allow-empty-passwords?)))