Add Aircraft.MakeReservation.

This provides a simpler method for making reservations and also ensures the previous reservation is definitely unreserved before being discarded.

OpenRA.Mods.Common/Activities/Air/HeliReturnToBase.cs

@@ -53,13 +53,7 @@ namespace OpenRA.Mods.Common.Activities
 					return Util.SequenceActivities(new HeliFly(self, Target.FromActor(nearestHpad)));
 			}
 
-			var res = dest.TraitOrDefault<Reservable>();
-
-			if (res != null)
-			{
-				heli.UnReserve();
-				heli.Reservation = res.Reserve(dest, self, heli);
-			}
+			heli.MakeReservation(dest);
 
 			var exit = dest.Info.TraitInfos<ExitInfo>().FirstOrDefault();
 			var offset = (exit != null) ? exit.SpawnOffset : WVec.Zero;

OpenRA.Mods.Common/Activities/Air/ReturnToBase.cs

@@ -50,12 +50,7 @@ namespace OpenRA.Mods.Common.Activities
 			if (dest == null)
 				return;
 
-			var res = dest.TraitOrDefault<Reservable>();
-			if (res != null)
-			{
-				plane.UnReserve();
-				plane.Reservation = res.Reserve(dest, self, plane);
-			}
+			plane.MakeReservation(dest);
 
 			var landPos = dest.CenterPosition;
 			var altitude = planeInfo.CruiseAltitude.Length;

OpenRA.Mods.Common/Traits/Air/Aircraft.cs

@@ -92,11 +92,11 @@ namespace OpenRA.Mods.Common.Traits
 		readonly Actor self;
 
 		UpgradeManager um;
+		IDisposable reservation;
 
 		[Sync] public int Facing { get; set; }
 		[Sync] public WPos CenterPosition { get; private set; }
 		public CPos TopLeft { get { return self.World.Map.CellContaining(CenterPosition); } }
-		public IDisposable Reservation;
 		public int ROT { get { return Info.ROT; } }
 
 		bool airborne;
@@ -257,22 +257,24 @@ namespace OpenRA.Mods.Common.Traits
 			if (afld == null)
 				return;
 
-			var res = afld.TraitOrDefault<Reservable>();
+			MakeReservation(afld);
+		}
 
-			if (res != null)
-			{
-				UnReserve();
-				Reservation = res.Reserve(afld, self, this);
-			}
+		public void MakeReservation(Actor target)
+		{
+			UnReserve();
+			var reservable = target.TraitOrDefault<Reservable>();
+			if (reservable != null)
+				reservation = reservable.Reserve(target, self, this);
 		}
 
 		public void UnReserve()
 		{
-			if (Reservation != null)
-			{
-				Reservation.Dispose();
-				Reservation = null;
-			}
+			if (reservation == null)
+				return;
+
+			reservation.Dispose();
+			reservation = null;
 		}
 
 		public bool AircraftCanEnter(Actor a)
@@ -448,12 +450,7 @@ namespace OpenRA.Mods.Common.Traits
 			if (target.Positions.Any(p => self.World.ActorMap.GetActorsAt(self.World.Map.CellContaining(p)).Any(a => a != self && a != target.Actor)))
 				return false;
 
-			var res = target.Actor.TraitOrDefault<Reservable>();
-			if (res == null)
-				return true;
-
-			UnReserve();
-			Reservation = res.Reserve(target.Actor, self, this);
+			MakeReservation(target.Actor);
 			return true;
 		}
 
@@ -541,12 +538,7 @@ namespace OpenRA.Mods.Common.Traits
 					}
 					else
 					{
-						var res = order.TargetActor.TraitOrDefault<Reservable>();
-						if (res != null)
-						{
-							UnReserve();
-							Reservation = res.Reserve(order.TargetActor, self, this);
-						}
+						MakeReservation(order.TargetActor);
 
 						Action enter = () =>
 						{