add initial Services container

Blarg.GameFramework/Blarg.GameFramework.csproj

@@ -157,6 +157,8 @@
     <Compile Include="Graphics\ScreenEffects\DimEffect.cs" />
     <Compile Include="Graphics\ScreenEffects\FadeEffect.cs" />
     <Compile Include="Graphics\ScreenEffects\FlashEffect.cs" />
+    <Compile Include="Services.cs" />
+    <Compile Include="IService.cs" />
   </ItemGroup>
   <Import Project="$(MSBuildExtensionsPath32)\Microsoft\Portable\$(TargetFrameworkVersion)\Microsoft.Portable.CSharp.targets" />
   <ItemGroup>

Blarg.GameFramework/IService.cs

@@ -0,0 +1,11 @@
+using System;
+
+namespace Blarg.GameFramework
+{
+	public interface IService
+	{
+		void OnRegister();
+		void OnUnregister();
+	}
+}
+

Blarg.GameFramework/Services.cs

@@ -0,0 +1,66 @@
+using System;
+using System.Collections.Generic;
+
+namespace Blarg.GameFramework
+{
+	public static class Services
+	{
+		static Dictionary<Type, object> _services = new Dictionary<Type, object>();
+
+		public static void Register(object service)
+		{
+			if (service == null)
+				throw new ArgumentNullException("service");
+			var type = service.GetType();
+			if (type.IsValueType)
+				throw new ArgumentException("Services cannot be used with value types.", "service");
+
+			if (_services.ContainsKey(type))
+				throw new InvalidOperationException("Service object of this type has already been registered.");
+
+			if (service is IService)
+				((IService)service).OnRegister();
+
+			_services.Add(type, service);
+		}
+
+		public static void Unregister(object service)
+		{
+			if (service == null)
+				throw new ArgumentNullException("service");
+			var type = service.GetType();
+			if (type.IsValueType)
+				throw new ArgumentException("Services cannot be used with value types.", "service");
+
+			object registeredService;
+			_services.TryGetValue(type, out registeredService);
+			if (registeredService == null)
+				return;
+
+			if (registeredService != service)
+				throw new InvalidOperationException("This is not the service object that was registered under this type.");
+
+			_services.Remove(type);
+
+			if (registeredService is IService)
+				((IService)registeredService).OnUnregister();
+		}
+
+		public static T Get<T>() where T : class
+		{
+			var type = typeof(T);
+			return Get(type) as T;
+		}
+
+		public static object Get(Type type)
+		{
+			if (type.IsValueType)
+				throw new ArgumentException("Services cannot be used with value types.", "type");
+
+			object service;
+			_services.TryGetValue(type, out service);
+			return service;
+		}
+	}
+}
+