[folks] core: Add RoleDetails.change_roles()

[Philip Withnall <pwithnall src gnome org>]

commit 418a2f2338d131769f80b3d264b3b015c785114e
Author: Philip Withnall <philip tecnocode co uk>
Date:   Tue Aug 30 20:11:53 2011 +0100

    core: Add RoleDetails.change_roles()
    
    This allows the roles of an implementing class to be changed asynchronously
    with proper error notification.
    
    Helps: bgo#657510

 backends/tracker/lib/trf-persona.vala |   19 +++++++++++++++----
 folks/individual.vala                 |    9 ++-------
 folks/role-details.vala               |   22 ++++++++++++++++++++++
 3 files changed, 39 insertions(+), 11 deletions(-)
---
diff --git a/backends/tracker/lib/trf-persona.vala b/backends/tracker/lib/trf-persona.vala
index f3b947e..18ebf1b 100644
--- a/backends/tracker/lib/trf-persona.vala
+++ b/backends/tracker/lib/trf-persona.vala
@@ -283,13 +283,22 @@ public class Trf.Persona : Folks.Persona,
   /**
    * { inheritDoc}
    */
+  [CCode (notify = false)]
   public Set<RoleFieldDetails> roles
     {
       get { return this._roles_ro; }
-      public set
-        {
-          ((Trf.PersonaStore) this.store)._set_roles (this, value);
-        }
+      set { this.change_roles.begin (value); }
+    }
+
+  /**
+   * { inheritDoc}
+   *
+   * @since UNRELEASED
+   */
+  public async void change_roles (Set<RoleFieldDetails> roles)
+      throws PropertyError
+    {
+      yield ((Trf.PersonaStore) this.store)._set_roles (this, roles);
     }
 
   private HashSet<NoteFieldDetails> _notes;
@@ -934,6 +943,8 @@ public class Trf.Persona : Folks.Persona,
 
       this._roles = role_fds;
       this._roles_ro = this._roles.read_only_view;
+
+      this.notify_property ("roles");
     }
 
   internal bool _add_role (string tracker_id, string? role, string? title, string? org)
diff --git a/folks/individual.vala b/folks/individual.vala
index e5ac6c6..6c7f64d 100644
--- a/folks/individual.vala
+++ b/folks/individual.vala
@@ -423,16 +423,11 @@ public class Folks.Individual : Object,
   /**
    * { inheritDoc}
    */
+  [CCode (notify = false)]
   public Set<RoleFieldDetails> roles
     {
       get { return this._roles_ro; }
-      private set
-        {
-          this._roles.clear ();
-          foreach (var role in value)
-            this._roles.add (role);
-          this.notify_property ("roles");
-        }
+      set { this.change_roles.begin (value); } /* not writeable */
     }
 
   private HashSet<string> _local_ids;
diff --git a/folks/role-details.vala b/folks/role-details.vala
index cccc5de..cac9f65 100644
--- a/folks/role-details.vala
+++ b/folks/role-details.vala
@@ -1,5 +1,6 @@
 /*
  * Copyright (C) 2011 Collabora Ltd.
+ * Copyright (C) 2011 Philip Withnall
  *
  * This library is free software: you can redistribute it and/or modify
  * it under the terms of the GNU Lesser General Public License as published by
@@ -17,6 +18,7 @@
  * Authors:
  *       Raul Gutierrez Segales <raul gutierrez segales collabora co uk>
  *       Travis Reitter <travis reitter collabora co uk>
+ *       Philip Withnall <philip tecnocode co uk>
  */
 
 using Gee;
@@ -197,4 +199,24 @@ public interface Folks.RoleDetails : Object
    * @since 0.6.0
    */
   public abstract Set<RoleFieldDetails> roles { get; set; }
+
+  /**
+   * Change the contact's roles.
+   *
+   * It's preferred to call this rather than setting { link RoleDetails.roles}
+   * directly, as this method gives error notification and will only return once
+   * the roles have been written to the relevant backing store (or the
+   * operation's failed).
+   *
+   * @param roles the set of roles
+   * @throws PropertyError if setting the roles failed
+   * @since UNRELEASED
+   */
+  public virtual async void change_roles (Set<RoleFieldDetails> roles)
+      throws PropertyError
+    {
+      /* Default implementation. */
+      throw new PropertyError.NOT_WRITEABLE (
+          _("Roles are not writeable on this contact."));
+    }
 }