Tidy up Activity.Cancel(), make Tick abstract

OpenRA.Mods.RA/Activities/CallFunc.cs

@@ -33,13 +33,10 @@ namespace OpenRA.Mods.RA.Activities
 			return NextActivity;
 		}
 
-		protected override bool OnCancel(Actor self)
+		public override void Cancel(Actor self)
 		{
-			if (!interruptable)
-				return false;
-			
-			a = null;
-			return true;
+			if (interruptable)
+				base.Cancel(self);
 		}
 	}
 }

OpenRA.Mods.RA/Activities/DeliverOre.cs

@@ -23,6 +23,7 @@ namespace OpenRA.Mods.RA.Activities
 
 		public override Activity Tick( Actor self )
 		{
+			// TODO: wtf is this?
 			if( NextActivity != null )
 				return NextActivity;
 
@@ -48,11 +49,8 @@ namespace OpenRA.Mods.RA.Activities
 			}
 			return Util.SequenceActivities( new Wait(10), this );
 		}
-
-		protected override bool OnCancel(Actor self)
-		{
-			// TODO: allow canceling of deliver orders?
-			return false;
-		}
+		
+		// Cannot be cancelled
+		public override void Cancel(Actor self) { }
 	}
 }

OpenRA.Mods.RA/Activities/MakeAnimation.cs

@@ -30,7 +30,6 @@ namespace OpenRA.Mods.RA.Activities
 		bool started = false;
 		public override Activity Tick( Actor self )
 		{
-			if (IsCanceled) return NextActivity;
 			if (!started)
 			{
 				var rb = self.Trait<RenderBuilding>();
@@ -51,7 +50,7 @@ namespace OpenRA.Mods.RA.Activities
 			return complete ? NextActivity : this;
 		}
 		
-		// Not actually cancellable
-		protected override bool OnCancel( Actor self ) { return false; }
+		// Cannot be cancelled
+		public override void Cancel( Actor self ) { }
 	}
 }

OpenRA.Mods.RA/Activities/RAHarvesterDockSequence.cs

@@ -70,10 +70,10 @@ namespace OpenRA.Mods.RA
 			throw new InvalidOperationException("Invalid harvester dock state");
 		}
 
-		protected override bool OnCancel(Actor self)
+		public override void Cancel(Actor self)
 		{
 			state = State.Undock;
-			return true;
+			base.Cancel(self);
 		}
 
 		public override IEnumerable<Target> GetTargets( Actor self )

OpenRA.Mods.RA/Activities/Sell.cs

@@ -40,7 +40,7 @@ namespace OpenRA.Mods.RA.Activities
 			return this;
 		}
 
-		// Not actually cancellable
-		protected override bool OnCancel( Actor self ) { return false; }
+		// Cannot be cancelled
+		public override void Cancel( Actor self ) { }
 	}
 }

OpenRA.Mods.RA/Activities/Wait.cs

@@ -27,15 +27,16 @@ namespace OpenRA.Mods.RA.Activities
 		
 		public override Activity Tick(Actor self)
 		{
-			if (remainingTicks-- == 0) return NextActivity;
-			return this;
+			return (remainingTicks-- == 0) ? NextActivity: this;
 		}
 
-		protected override bool OnCancel( Actor self )
+		public override void Cancel( Actor self )
 		{
-			if( !interruptable ) return false;
+			if( !interruptable )
+				return;
+
 			remainingTicks = 0;
-			return true;
+			base.Cancel(self);
 		}
 	}
 }