Allow collection ID to be set without copying shared data

kaevent.cpp

@@ -306,7 +306,7 @@ class KAEvent::Private : public QSharedData
 #ifndef KALARMCAL_USE_KRESOURCES
         QMap<QByteArray, QString> mCustomProperties;  // KCal::Event's non-KAlarm custom properties
         Akonadi::Item::Id  mItemId;            // Akonadi::Item ID for this event
-        Akonadi::Collection::Id mCollectionId; // ID of collection containing the event, or for a displaying event,
+        mutable Akonadi::Collection::Id mCollectionId; // ID of collection containing the event, or for a displaying event,
                                                // saved collection ID (not the collection the event is in)
 #else
         QString            mOriginalResourceId;// saved resource ID (not the resource the event is in)
@@ -1888,6 +1888,11 @@ void KAEvent::setCollectionId(Akonadi::Collection::Id id)
     d->mCollectionId = id;
 }
 
+void KAEvent::setCollectionId_const(Akonadi::Collection::Id id) const
+{
+    d->mCollectionId = id;
+}
+
 Akonadi::Collection::Id KAEvent::collectionId() const
 {
     // A displaying alarm contains the event's original collection ID

kaevent.h

@@ -472,6 +472,14 @@ class KALARMCAL_EXPORT KAEvent
 #ifndef KALARMCAL_USE_KRESOURCES
         /** Set the ID of the Akonadi Collection which contains the event. */
         void setCollectionId(Akonadi::Collection::Id id);
+        /** Set the ID of the Akonadi Collection which contains the event.
+         *  \warning This is a const method, which means that any other instance
+         *           which references the same shared data will also be
+         *           updated. It is designed to be used when a KAEvent is
+         *           being created from an Akonadi Item, to avoid unnecessary
+         *           copying. Use with caution!
+         */
+        void setCollectionId_const(Akonadi::Collection::Id id) const;
         /** Return the ID of the Akonadi Collection which contains the event. */
         Akonadi::Collection::Id  collectionId() const;