Use a simpler CascadeStyle singleton implementation. It has fewer classes, and also avoids the complex issue with type initialization order.

Author: oskarb

src/NHibernate.Test/NHSpecificTest/NH3383/FixtureByCode.cs

@@ -19,6 +19,46 @@ protected override HbmMapping GetMappings()
 			return mapper.CompileMappingForAllExplicitlyAddedEntities();
 		}
 
+
+		[Test]
+		public void DeserializedCascadeStyleRefersToSameObject()
+		{
+			CascadeStyle deserializedCascadeStyle;
+
+			using (var configMemoryStream = new MemoryStream())
+			{
+				var formatter = new BinaryFormatter();
+				formatter.Serialize(configMemoryStream, CascadeStyle.Evict);
+				configMemoryStream.Position = 0;
+				deserializedCascadeStyle = (CascadeStyle) formatter.Deserialize(configMemoryStream);
+			}
+
+			Assert.That(deserializedCascadeStyle, Is.SameAs(CascadeStyle.Evict));
+		}
+
+
+		[Test]
+		public void CanRoundTripSerializedMultipleCascadeStyle()
+		{
+			CascadeStyle startingCascadeStyle =
+				new CascadeStyle.MultipleCascadeStyle(new[] {CascadeStyle.Delete, CascadeStyle.Lock});
+			CascadeStyle deserializedCascadeStyle;
+
+			using (var configMemoryStream = new MemoryStream())
+			{
+				var formatter = new BinaryFormatter();
+				formatter.Serialize(configMemoryStream, startingCascadeStyle);
+				configMemoryStream.Position = 0;
+				deserializedCascadeStyle = (CascadeStyle)formatter.Deserialize(configMemoryStream);
+			}
+
+			Assert.That(deserializedCascadeStyle, Is.TypeOf<CascadeStyle.MultipleCascadeStyle>());
+			Assert.That(deserializedCascadeStyle.ToString(),
+			            Is.EqualTo(
+				            "[NHibernate.Engine.CascadeStyle+DeleteCascadeStyle,NHibernate.Engine.CascadeStyle+LockCascadeStyle]"));
+		}
+
+
 		[Test]
 		public void DeserializedPropertyMapping_RefersToSameCascadeStyle()
 		{

src/NHibernate/Engine/CascadeStyle.cs

@@ -2,15 +2,14 @@
 using System.Collections.Generic;
 using System.Runtime.Serialization;
 using System.Security;
-using System.Security.Permissions;
 using NHibernate.Util;
 
 namespace NHibernate.Engine
 {
 	/// <summary> A contract for defining the aspects of cascading various persistence actions. </summary>
 	/// <seealso cref="CascadingAction"/>
 	[Serializable]
-	public abstract class CascadeStyle
+	public abstract class CascadeStyle : ISerializable
 	{
 		/// <summary> package-protected constructor</summary>
 		internal CascadeStyle() {}
@@ -29,6 +28,19 @@ static CascadeStyle()
 			Styles["remove"] = Delete; // adds remove as a sort-of alias for delete...
 			Styles["delete-orphan"] = DeleteOrphan;
 			Styles["none"] = None;
+
+			AliasByStyle[All] = "all";
+			AliasByStyle[AllDeleteOrphan] = "all-delete-orphan";
+			AliasByStyle[Update] = "save-update";
+			AliasByStyle[Persist] = "persist";
+			AliasByStyle[Merge] = "merge";
+			AliasByStyle[Lock] = "lock";
+			AliasByStyle[Refresh] = "refresh";
+			AliasByStyle[Replicate] = "replicate";
+			AliasByStyle[Evict] = "evict";
+			AliasByStyle[Delete] = "delete";
+			AliasByStyle[DeleteOrphan] = "delete-orphan";
+			AliasByStyle[None] = "none";
 		}
 
 		#region The CascadeStyle contract
@@ -66,7 +78,8 @@ public virtual bool HasOrphanDelete
 
 		#region  Static helper methods
 
-		internal static readonly Dictionary<string, CascadeStyle> Styles = new Dictionary<string, CascadeStyle>();
+		private static readonly Dictionary<string, CascadeStyle> Styles = new Dictionary<string, CascadeStyle>();
+		private static readonly Dictionary<CascadeStyle, string> AliasByStyle = new Dictionary<CascadeStyle, string>();
 
 		/// <summary> Factory method for obtaining named cascade styles </summary>
 		/// <param name="cascade">The named cascade style name. </param>
@@ -80,53 +93,43 @@ public static CascadeStyle GetCascadeStyle(string cascade)
 				return style;
 		}
 
-		private static void RunTypeConstructor()
+		void ISerializable.GetObjectData(SerializationInfo info, StreamingContext context)
 		{
-			// No code needed.
+			string alias = AliasByStyle[this];
+			info.SetType(typeof (CascadeStyleSingletonReference));
+			info.AddValue("cascadestyle", alias, typeof (string));
 		}
 
-		#endregion
-
-		#region The CascadeStyle implementations
-
 		[Serializable]
-		private abstract class SingletonCascadeStyle<TConcrete> : CascadeStyle, ISerializable
-			where TConcrete : class, new()
+		private sealed class CascadeStyleSingletonReference : IObjectReference, ISerializable
 		{
-			public static readonly TConcrete Instance = new TConcrete();
+			private readonly string _cascadeStyle;
 
-#if NET_4_0
-			[SecurityCritical]
-#else
-			[SecurityPermission(SecurityAction.LinkDemand, Flags = SecurityPermissionFlag.SerializationFormatter)]
-#endif
-			public void GetObjectData(SerializationInfo info, StreamingContext context)
+			void ISerializable.GetObjectData(SerializationInfo info, StreamingContext context)
 			{
-				// Don't serialize the real object, that could cause multiple objects of the same
-				// singleton type after deserialization.
-				info.SetType(typeof(CascadeStyleReference));
+				throw new NotImplementedException("This class should not be serialized directly.");
 			}
 
-			[Serializable]
-			private sealed class CascadeStyleReference : IObjectReference
+			private CascadeStyleSingletonReference(SerializationInfo info, StreamingContext context)
 			{
-#if NET_4_0
-				[SecurityCritical]
-#endif
-				public Object GetRealObject(StreamingContext context)
-				{
-					// First make sure that the type constructor of the base class was already executed.
-					// If this isn't the case 'Instance' can't be constructed and will stay null.
-					CascadeStyle.RunTypeConstructor();
+				_cascadeStyle = (string) info.GetValue("cascadestyle", typeof (string));
+			}
 
-					// Return the singleton instance of this CascadeStyle.
-					return Instance;
-				}
+			[SecurityCritical]
+			Object IObjectReference.GetRealObject(StreamingContext context)
+			{
+				// Redirect to the singleton instance for the correct cascade style.
+				return GetCascadeStyle(_cascadeStyle);
 			}
 		}
 
+		#endregion
+
+		#region The CascadeStyle implementations
+
+
 		[Serializable]
-		private class AllDeleteOrphanCascadeStyle : SingletonCascadeStyle<AllDeleteOrphanCascadeStyle>
+		private class AllDeleteOrphanCascadeStyle : CascadeStyle
 		{
 			public override bool DoCascade(CascadingAction action)
 			{
@@ -139,7 +142,7 @@ public override bool HasOrphanDelete
 		}
 
 		[Serializable]
-		private class AllCascadeStyle : SingletonCascadeStyle<AllCascadeStyle>
+		private class AllCascadeStyle : CascadeStyle
 		{
 			public override bool DoCascade(CascadingAction action)
 			{
@@ -148,7 +151,7 @@ public override bool DoCascade(CascadingAction action)
 		}
 
 		[Serializable]
-		private class UpdateCascadeStyle : SingletonCascadeStyle<UpdateCascadeStyle>
+		private class UpdateCascadeStyle : CascadeStyle
 		{
 			public override bool DoCascade(CascadingAction action)
 			{
@@ -157,7 +160,7 @@ public override bool DoCascade(CascadingAction action)
 		}
 
 		[Serializable]
-		private class LockCascadeStyle : SingletonCascadeStyle<LockCascadeStyle>
+		private class LockCascadeStyle : CascadeStyle
 		{
 			public override bool DoCascade(CascadingAction action)
 			{
@@ -166,7 +169,7 @@ public override bool DoCascade(CascadingAction action)
 		}
 
 		[Serializable]
-		private class RefreshCascadeStyle : SingletonCascadeStyle<RefreshCascadeStyle>
+		private class RefreshCascadeStyle : CascadeStyle
 		{
 			public override bool DoCascade(CascadingAction action)
 			{
@@ -175,7 +178,7 @@ public override bool DoCascade(CascadingAction action)
 		}
 
 		[Serializable]
-		private class EvictCascadeStyle : SingletonCascadeStyle<EvictCascadeStyle>
+		private class EvictCascadeStyle : CascadeStyle
 		{
 			public override bool DoCascade(CascadingAction action)
 			{
@@ -184,7 +187,7 @@ public override bool DoCascade(CascadingAction action)
 		}
 
 		[Serializable]
-		private class ReplicateCascadeStyle : SingletonCascadeStyle<ReplicateCascadeStyle>
+		private class ReplicateCascadeStyle : CascadeStyle
 		{
 			public override bool DoCascade(CascadingAction action)
 			{
@@ -193,7 +196,7 @@ public override bool DoCascade(CascadingAction action)
 		}
 
 		[Serializable]
-		private class MergeCascadeStyle : SingletonCascadeStyle<MergeCascadeStyle>
+		private class MergeCascadeStyle : CascadeStyle
 		{
 			public override bool DoCascade(CascadingAction action)
 			{
@@ -202,7 +205,7 @@ public override bool DoCascade(CascadingAction action)
 		}
 
 		[Serializable]
-		private class PersistCascadeStyle : SingletonCascadeStyle<PersistCascadeStyle>
+		private class PersistCascadeStyle : CascadeStyle
 		{
 			public override bool DoCascade(CascadingAction action)
 			{
@@ -211,7 +214,7 @@ public override bool DoCascade(CascadingAction action)
 		}
 
 		[Serializable]
-		private class DeleteCascadeStyle : SingletonCascadeStyle<DeleteCascadeStyle>
+		private class DeleteCascadeStyle : CascadeStyle
 		{
 			public override bool DoCascade(CascadingAction action)
 			{
@@ -220,7 +223,7 @@ public override bool DoCascade(CascadingAction action)
 		}
 
 		[Serializable]
-		private class DeleteOrphanCascadeStyle : SingletonCascadeStyle<DeleteOrphanCascadeStyle>
+		private class DeleteOrphanCascadeStyle : CascadeStyle
 		{
 			public override bool DoCascade(CascadingAction action)
 			{
@@ -239,7 +242,7 @@ public override bool HasOrphanDelete
 		}
 
 		[Serializable]
-		private class NoneCascadeStyle : SingletonCascadeStyle<NoneCascadeStyle>
+		private class NoneCascadeStyle : CascadeStyle
 		{
 			public override bool DoCascade(CascadingAction action)
 			{
@@ -248,14 +251,24 @@ public override bool DoCascade(CascadingAction action)
 		}
 
 		[Serializable]
-		public sealed class MultipleCascadeStyle : CascadeStyle
+		public sealed class MultipleCascadeStyle : CascadeStyle, ISerializable
 		{
 			private readonly CascadeStyle[] styles;
 			public MultipleCascadeStyle(CascadeStyle[] styles)
 			{
 				this.styles = styles;
 			}
 
+			private MultipleCascadeStyle(SerializationInfo info, StreamingContext context)
+			{
+				styles = (CascadeStyle[])info.GetValue("styles", typeof(CascadeStyle[]));
+			}
+
+			void ISerializable.GetObjectData(SerializationInfo info, StreamingContext context)
+			{
+				info.AddValue("styles", styles);
+			}
+
 			public override bool DoCascade(CascadingAction action)
 			{
 				for (int i = 0; i < styles.Length; i++)
@@ -295,40 +308,40 @@ public override string ToString()
 		}
 
 		/// <summary> save / delete / update / evict / lock / replicate / merge / persist + delete orphans</summary>
-		public static readonly CascadeStyle AllDeleteOrphan = AllDeleteOrphanCascadeStyle.Instance;
+		public static readonly CascadeStyle AllDeleteOrphan = new AllDeleteOrphanCascadeStyle();
 
 		/// <summary> save / delete / update / evict / lock / replicate / merge / persist</summary>
-		public static readonly CascadeStyle All = AllCascadeStyle.Instance;
+		public static readonly CascadeStyle All = new AllCascadeStyle();
 
 		/// <summary> save / update</summary>
-		public static readonly CascadeStyle Update = UpdateCascadeStyle.Instance;
+		public static readonly CascadeStyle Update = new UpdateCascadeStyle();
 
 		/// <summary> lock</summary>
-		public static readonly CascadeStyle Lock = LockCascadeStyle.Instance;
+		public static readonly CascadeStyle Lock = new LockCascadeStyle();
 
 		/// <summary> refresh</summary>
-		public static readonly CascadeStyle Refresh = RefreshCascadeStyle.Instance;
+		public static readonly CascadeStyle Refresh = new RefreshCascadeStyle();
 
 		/// <summary> evict</summary>
-		public static readonly CascadeStyle Evict = EvictCascadeStyle.Instance;
+		public static readonly CascadeStyle Evict = new EvictCascadeStyle();
 
 		/// <summary> replicate</summary>
-		public static readonly CascadeStyle Replicate = ReplicateCascadeStyle.Instance;
+		public static readonly CascadeStyle Replicate = new ReplicateCascadeStyle();
 
 		/// <summary> merge</summary>
-		public static readonly CascadeStyle Merge = MergeCascadeStyle.Instance;
+		public static readonly CascadeStyle Merge = new MergeCascadeStyle();
 
 		/// <summary> create</summary>
-		public static readonly CascadeStyle Persist = PersistCascadeStyle.Instance;
+		public static readonly CascadeStyle Persist = new PersistCascadeStyle();
 
 		/// <summary> delete</summary>
-		public static readonly CascadeStyle Delete = DeleteCascadeStyle.Instance;
+		public static readonly CascadeStyle Delete = new DeleteCascadeStyle();
 
 		/// <summary> delete + delete orphans</summary>
-		public static readonly CascadeStyle DeleteOrphan = DeleteOrphanCascadeStyle.Instance;
+		public static readonly CascadeStyle DeleteOrphan = new DeleteOrphanCascadeStyle();
 
 		/// <summary> no cascades</summary>
-		public static readonly CascadeStyle None = NoneCascadeStyle.Instance;
+		public static readonly CascadeStyle None = new NoneCascadeStyle();
 
 		#endregion
 	}