ClonesProductionUnits:

string[] CloneableTypes	checks Cloneable.Types

Cloneable:
	string[] Types checked by ClonesProductionUnits.CloneableTypes

Added INotifyOtherProduction
	for notifying self when another actor
	produces a unit.

OpenRA.Game/Traits/TraitsInterfaces.cs

@@ -74,6 +74,7 @@ namespace OpenRA.Traits
 	public interface INotifyBuildComplete { void BuildingComplete(Actor self); }
 	public interface INotifyBuildingPlaced { void BuildingPlaced(Actor self); }
 	public interface INotifyProduction { void UnitProduced(Actor self, Actor other, CPos exit); }
+	public interface INotifyOtherProduction { void UnitProducedByOther(Actor self, Actor producer, Actor produced); }
 	public interface INotifyDelivery { void IncomingDelivery(Actor self); void Delivered(Actor self); }
 	public interface INotifyOwnerChanged { void OnOwnerChanged(Actor self, Player oldOwner, Player newOwner); }
 	public interface INotifyEffectiveOwnerChanged { void OnEffectiveOwnerChanged(Actor self, Player oldEffectiveOwner, Player newEffectiveOwner); }

OpenRA.Mods.RA/Buildings/ClonesProducedUnits.cs

@@ -0,0 +1,50 @@
+ #region Copyright & License Information
+ /*
+  * Copyright 2007-2014 The OpenRA Developers (see AUTHORS)
+  * This file is part of OpenRA, which is free software. It is made
+  * available to you under the terms of the GNU General Public License
+  * as published by the Free Software Foundation. For more information,
+  * see COPYING.
+  */
+ #endregion
+
+using System;
+using System.Linq;
+using OpenRA.Traits;
+
+namespace OpenRA.Mods.RA
+{
+	[Desc("Creates a free duplicate of produced units.")]
+	public class ClonesProducedUnitsInfo : ITraitInfo, Requires<ProductionInfo>, Requires<ExitInfo>
+	{
+		[Desc("Uses the \"Cloneable\" trait to determine whether or not we should clone a produced unit.")]
+		public readonly string[] CloneableTypes = { };
+
+		public object Create(ActorInitializer init) { return new ClonesProducedUnits(init.self, this); }
+	}
+
+	public class ClonesProducedUnits : INotifyOtherProduction
+	{
+		readonly ClonesProducedUnitsInfo info;
+		readonly Production production;
+
+		public ClonesProducedUnits(Actor self, ClonesProducedUnitsInfo info)
+		{
+			this.info = info;
+			production = self.Trait<Production>();
+		}
+
+		public void UnitProducedByOther(Actor self, Actor producer, Actor produced)
+		{
+			// No recursive cloning!
+			if (producer.HasTrait<ClonesProducedUnits>())
+				return;
+
+			var ci = produced.Info.Traits.GetOrDefault<CloneableInfo>();
+			if (ci == null || !info.CloneableTypes.Intersect(ci.Types).Any())
+				return;
+
+			production.Produce(self, produced.Info, self.Owner.Country.Race);
+		}
+	}
+}

OpenRA.Mods.RA/Cloneable.cs

@@ -0,0 +1,24 @@
+ #region Copyright & License Information
+ /*
+  * Copyright 2007-2014 The OpenRA Developers (see AUTHORS)
+  * This file is part of OpenRA, which is free software. It is made
+  * available to you under the terms of the GNU General Public License
+  * as published by the Free Software Foundation. For more information,
+  * see COPYING.
+  */
+ #endregion
+
+using System;
+using OpenRA.Traits;
+
+namespace OpenRA.Mods.RA
+{
+	[Desc("Actors with the \"ClonesProducedUnits\" trait will produce a free duplicate of me.")]
+	public class CloneableInfo : TraitInfo<Cloneable>
+	{
+		[Desc("This unit's cloneable type is:")]
+		public readonly string[] Types = { };
+	}
+
+	public class Cloneable { }
+}

OpenRA.Mods.RA/OpenRA.Mods.RA.csproj

@@ -528,6 +528,8 @@
     <Compile Include="Graphics\TextRenderable.cs" />
     <Compile Include="Graphics\VoxelRenderable.cs" />
     <Compile Include="Air\FlyAwayOnIdle.cs" />
+    <Compile Include="Buildings\ClonesProducedUnits.cs" />
+    <Compile Include="Cloneable.cs" />
   </ItemGroup>
   <ItemGroup>
     <ProjectReference Include="..\OpenRA.Game\OpenRA.Game.csproj">

OpenRA.Mods.RA/Production.cs

@@ -10,6 +10,7 @@
 
 using System;
 using System.Drawing;
+using System.Collections.Generic;
 using System.Linq;
 using OpenRA.Mods.RA.Move;
 using OpenRA.Primitives;
@@ -96,6 +97,12 @@ namespace OpenRA.Mods.RA
 				if (!self.IsDead())
 					foreach (var t in self.TraitsImplementing<INotifyProduction>())
 						t.UnitProduced(self, newUnit, exit);
+
+				var notifyOthers = self.World.ActorsWithTrait<INotifyOtherProduction>()
+					.Where(a => a.Actor.Owner == self.Owner);
+
+				foreach (var notify in notifyOthers)
+					notify.Trait.UnitProducedByOther(notify.Actor, self, newUnit);
 			});
 		}
 

mods/ra/rules/defaults.yaml

@@ -180,6 +180,8 @@
 		KilledOnImpassableTerrain: true
 		ParachuteSequence: parach
 		ShadowSequence: parach-shadow
+	Cloneable:
+		Types: Infantry
 
 ^Ship:
 	AppearsOnRadar: