Some method

src/Engine.cs

@@ -1,6 +1,7 @@
 using System;
 using System.Reflection;
 using System.Collections.Generic;
+using System.Linq;
 
 namespace Encompass
 {
@@ -116,5 +117,17 @@ namespace Encompass
                 throw new IllegalMessageReadException("Engine {0} tried to read undeclared Message {1}", this.GetType().Name, typeof(TMessage).Name);
             }
         }
+
+        protected bool Some<TMessage>() where TMessage : struct, IMessage
+        {
+            if (readMessageTypes.Contains(typeof(TMessage)))
+            {
+                return messageManager.GetMessagesByType<TMessage>().Count() > 0;
+            }
+            else
+            {
+                throw new IllegalMessageReadException("Engine {0} tried to read undeclared Message {1}", this.GetType().Name, typeof(TMessage).Name);
+            }
+        }
     }
 }

test/EngineTest.cs

@@ -237,5 +237,42 @@ namespace Tests
             var ex = Assert.Throws<IllegalMessageEmitException>(() => world.Update(0.01f));
             Assert.That(ex.Message, Is.EqualTo("Engine UndeclaredMessageEmitEngine tried to emit undeclared Message MockMessage"));
         }
+
+        static bool someTest;
+
+        [Emits(typeof(MockMessage))]
+        class EmitMockMessageEngine : Engine
+        {
+            public override void Update(float dt)
+            {
+                MockMessage message;
+                message.myString = "howdy";
+
+                this.EmitMessage(message);
+            }
+        }
+
+        [Reads(typeof(MockMessage))]
+        class SomeTestEngine : Engine
+        {
+            public override void Update(float dt)
+            {
+                someTest = this.Some<MockMessage>();
+            }
+        }
+
+        [Test]
+        public void Some()
+        {
+            var worldBuilder = new WorldBuilder();
+            worldBuilder.AddEngine<EmitMockMessageEngine>();
+            worldBuilder.AddEngine<SomeTestEngine>();
+
+            var world = worldBuilder.Build();
+
+            world.Update(0.01f);
+
+            Assert.That(someTest, Is.True);
+        }
     }
 }