diff --git a/mocha-dotnet/src/lib/Mocha.Core/ClassImplementationRegistry.cs b/mocha-dotnet/src/lib/Mocha.Core/ClassImplementationRegistry.cs
new file mode 100644
index 0000000..af97e28
--- /dev/null
+++ b/mocha-dotnet/src/lib/Mocha.Core/ClassImplementationRegistry.cs
@@ -0,0 +1,71 @@
+// Copyright (C) 2025 Michael Becker  <alcexhim@gmail.com>
+// 
+// This file is part of Mocha.NET.
+// 
+// Mocha.NET is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+// 
+// Mocha.NET is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+// 
+// You should have received a copy of the GNU General Public License
+// along with Mocha.NET.  If not, see <https://www.gnu.org/licenses/>.
+
+using Mocha.Core.Oop;
+
+namespace Mocha.Core;
+
+public class ClassImplementationRegistry
+{
+	private Dictionary<Guid, ClassImplementation> implementations = new Dictionary<Guid, ClassImplementation>();
+	
+	public void Register<T>(Guid methodClassId, T implementation) where T : ClassImplementation
+	{
+		implementations[methodClassId] = implementation;
+	}
+
+	public bool Contains(Guid classGuid)
+	{
+		return implementations.ContainsKey(classGuid);
+	}
+	public bool Contains<T>(Guid classGuid) where T : ClassImplementation
+	{
+		if (implementations.ContainsKey(classGuid))
+		{
+			if (implementations[classGuid] is T)
+			{
+				return true;
+			}
+		}
+		return false;
+	}
+
+	public T Get<T>(Guid classGuid) where T : ClassImplementation
+	{
+		if (implementations.ContainsKey(classGuid))
+		{
+			if (implementations[classGuid] is T obj)
+			{
+				return obj;
+			}
+		}
+		throw new NotImplementedException(String.Format("implementation for class {0} not found or incorrect type", classGuid));
+	}
+	public bool TryGet<T>(Guid classGuid, out T? implementation) where T : ClassImplementation
+	{
+		if (implementations.ContainsKey(classGuid))
+		{
+			if (implementations[classGuid] is T obj)
+			{
+				implementation = obj;
+				return true;
+			}
+		}
+		implementation = null;
+		return false;
+	}
+}
\ No newline at end of file
diff --git a/mocha-dotnet/src/lib/Mocha.Core/Oms.cs b/mocha-dotnet/src/lib/Mocha.Core/Oms.cs
index eb40733..2657f8c 100644
--- a/mocha-dotnet/src/lib/Mocha.Core/Oms.cs
+++ b/mocha-dotnet/src/lib/Mocha.Core/Oms.cs
@@ -55,13 +55,13 @@ public abstract class Oms
 		MethodImplementation[] methodImplementations = MBS.Core.Reflection.TypeLoader.GetAvailableTypes<MethodImplementation>(new System.Reflection.Assembly[] { Assembly.GetExecutingAssembly() });
 		foreach (MethodImplementation impl in methodImplementations)
 		{
-			RegisterMethodImplementation(impl.ClassGuid, impl);
+			ClassImplementations.Register(impl.ClassGuid, impl);
 		}
 		
 		AttributeImplementation[] attributeImplementations = MBS.Core.Reflection.TypeLoader.GetAvailableTypes<AttributeImplementation>(new System.Reflection.Assembly[] { Assembly.GetExecutingAssembly() });
 		foreach (AttributeImplementation impl in attributeImplementations)
 		{
-			RegisterAttributeImplementation(impl.ClassGuid, impl);
+			ClassImplementations.Register(impl.ClassGuid, impl);
 		}
 	}
 
@@ -1219,17 +1219,7 @@ public abstract class Oms
 		return value;
 	}
 
-	private Dictionary<Guid, MethodImplementation> methodImplementations = new Dictionary<Guid, MethodImplementation>();
-	private void RegisterMethodImplementation(Guid methodClassId, MethodImplementation implementation)
-	{
-		methodImplementations[methodClassId] = implementation;
-	}
-
-	private Dictionary<Guid, AttributeImplementation> attributeImplementations = new Dictionary<Guid, AttributeImplementation>();
-	private void RegisterAttributeImplementation(Guid attributeClassId, AttributeImplementation implementation)
-	{
-		attributeImplementations[attributeClassId] = implementation;
-	}
+	public ClassImplementationRegistry ClassImplementations { get; } = new ClassImplementationRegistry();
 
 	public InstanceHandle Execute(OmsContext context, MethodBinding methodBinding, IInstanceReference? targetInstance = null)
 	{
@@ -1325,7 +1315,7 @@ public abstract class Oms
 					Console.Error.WriteLine("oms: error: assigns from work data not set for parameter assignment '{0}'", parm.GlobalIdentifier);
 					continue;
 				}
-				
+
 				if (IsInstanceOf(assignsFromWorkData, GetInstance(KnownInstanceGuids.Classes.Class)))
 				{
 					assignsFromWorkData = context.GetWorkData<IInstanceReference>(assignsFromWorkData);
@@ -1380,7 +1370,7 @@ public abstract class Oms
 		}
 		else
 		{
-			if (methodImplementations.ContainsKey(parentClassId))
+			if (ClassImplementations.TryGet<MethodImplementation>(parentClassId, out MethodImplementation? impl))
 			{
 				if (targetInstance == null)
 				{
@@ -1435,15 +1425,14 @@ public abstract class Oms
 					InstanceHandle pclassInstance = GetParentClass(hh);
 					context.SetWorkData(pclassInstance, hh);
 				}
-				retval = methodImplementations[parentClassId].Execute(this, context, methodOrMethodBinding);
+				retval = impl.Execute(this, context, methodOrMethodBinding);
+			}
+			else
+			{
+				throw new NotImplementedException(String.Format("method implementation not found for method class {0}", GetGlobalIdentifier(parentClass)));
 			}
 		}
-		if (retval == null)
-		{
-			// return InstanceHandle.Empty;
-			throw new NotImplementedException(String.Format("method implementation not found for method class {0}", GetGlobalIdentifier(parentClass)));
-		}
-		else
+		if (retval != null)
 		{
 			// context.StackTrace.Pop();
 			IDictionary<InstanceHandle, object?> dict = context.GetAllWorkData();
@@ -1455,6 +1444,11 @@ public abstract class Oms
 			}
 			return retval.Value;
 		}
+		else
+		{
+			// return InstanceHandle.Empty;
+			throw new InvalidOperationException(String.Format("method did not return work data for method class {0}", GetGlobalIdentifier(parentClass)));
+		}
 	}
 
 	private InstanceHandle ExecuteMethodBinding(OmsContext context, InstanceHandle methodBinding, IInstanceReference? targetInstance = null)
@@ -2787,10 +2781,6 @@ public abstract class Oms
 		Guid classGuid = GetGlobalIdentifier(parentClass);
 
 		// find AttributeImplementation whose ClassGuid matches
-		if (attributeImplementations.ContainsKey(classGuid))
-		{
-			return attributeImplementations[classGuid];
-		}
-		throw new NotImplementedException(String.Format("implementation for attribute class {0} not found", classGuid));
+		return ClassImplementations.Get<AttributeImplementation>(classGuid);
 	}
 }