feat: Update package.json to 1.6.0

Support contravariance/covariance

.github/ISSUE_TEMPLATE/feature-request.yaml

@@ -12,6 +12,6 @@ body:
   - type: textarea
     id: feature-description
     attributes:
-      label: Feature destription
+      label: Feature description
     validations:
       required: true

.github/ISSUE_TEMPLATE/improvement-request.yaml

@@ -12,6 +12,6 @@ body:
   - type: textarea
     id: improvement-description
     attributes:
-      label: Improvement destription
+      label: Improvement description
     validations:
       required: true

.github/workflows/package.yaml

@@ -14,7 +14,7 @@ jobs:
     steps:
       # Checkout
       - name: Checkout repository
-        uses: actions/checkout@v2
+        uses: actions/checkout@v4
         with:
           lfs: true
 
@@ -39,7 +39,7 @@ jobs:
 
       # Upload
       - name: Upload .unitypackage
-        uses: actions/upload-artifact@v2
+        uses: actions/upload-artifact@v4
         with:
           name: Unity Package
           path: Build

.github/workflows/release.yaml

@@ -18,7 +18,7 @@ jobs:
     outputs:
       sha: ${{ steps.commit.outputs.sha }}
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v4
       - name: Output package.json (Before)
         run: cat ${{ env.TARGET_FILE}}
 
@@ -69,7 +69,7 @@ jobs:
     timeout-minutes: 15
     steps:
       - run: echo ${{ needs.update-packagejson.outputs.sha }}
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v4
         with:
           ref: ${{ needs.update-packagejson.outputs.sha }}
 
@@ -97,7 +97,7 @@ jobs:
         working-directory: .
 
       # Store artifacts.
-      - uses: actions/upload-artifact@v2
+      - uses: actions/upload-artifact@v4
         with:
           name: SerializeReference-Extensions.unitypackage
           path: ./Build/SerializeReference-Extensions.unitypackage
@@ -119,7 +119,7 @@ jobs:
           prerelease: false
 
       # Download(All) Artifacts to current directory
-      - uses: actions/download-artifact@v2
+      - uses: actions/download-artifact@v4
       
       # Upload to Releases(unitypackage)
       - uses: actions/upload-release-asset@v1

Assets/Example/Example.cs

@@ -1,4 +1,3 @@
-#if UNITY_2019_3_OR_NEWER
 using System.Collections.Generic;
 using System;
 using UnityEditor;
@@ -42,6 +41,17 @@ public class Grape : Food
 	}
 }
 
+[Serializable]
+[HideInTypeMenu]
+public class Banana : Food
+{
+	public Banana ()
+	{
+		name = "Banana";
+		kcal = 100f;
+	}
+}
+
 public class Example : MonoBehaviour
 {
 
@@ -60,7 +70,8 @@ public class Example : MonoBehaviour
 	[SerializeReference, SubclassSelector]
 	public Food foodTwo = new Peach();
 
-	[SerializeReference, SubclassSelector]
+	// UseToStringAsLabel support on UNITY_2021_3_OR_NEWER
+	[SerializeReference, SubclassSelector(UseToStringAsLabel = true)]
 	public Food foodThree = new Grape();
 
 	[SerializeReference]
@@ -116,5 +127,3 @@ public class AppleDrawer : PropertyDrawer
 	}
 }
 #endif
-
-#endif

Assets/Example/Example.unity

@@ -13,7 +13,7 @@ OcclusionCullingSettings:
 --- !u!104 &2
 RenderSettings:
   m_ObjectHideFlags: 0
-  serializedVersion: 9
+  serializedVersion: 10
   m_Fog: 0
   m_FogColor: {r: 0.5, g: 0.5, b: 0.5, a: 1}
   m_FogMode: 3
@@ -38,13 +38,12 @@ RenderSettings:
   m_ReflectionIntensity: 1
   m_CustomReflection: {fileID: 0}
   m_Sun: {fileID: 0}
-  m_IndirectSpecularColor: {r: 0.44657898, g: 0.4964133, b: 0.5748178, a: 1}
+  m_IndirectSpecularColor: {r: 0, g: 0, b: 0, a: 1}
   m_UseRadianceAmbientProbe: 0
 --- !u!157 &3
 LightmapSettings:
   m_ObjectHideFlags: 0
   serializedVersion: 12
-  m_GIWorkflowMode: 1
   m_GISettings:
     serializedVersion: 2
     m_BounceScale: 1
@@ -67,9 +66,6 @@ LightmapSettings:
     m_LightmapParameters: {fileID: 0}
     m_LightmapsBakeMode: 1
     m_TextureCompression: 1
-    m_FinalGather: 0
-    m_FinalGatherFiltering: 1
-    m_FinalGatherRayCount: 256
     m_ReflectionCompression: 2
     m_MixedBakeMode: 2
     m_BakeBackend: 1
@@ -104,7 +100,7 @@ NavMeshSettings:
   serializedVersion: 2
   m_ObjectHideFlags: 0
   m_BuildSettings:
-    serializedVersion: 2
+    serializedVersion: 3
     agentTypeID: 0
     agentRadius: 0.5
     agentHeight: 2
@@ -117,7 +113,7 @@ NavMeshSettings:
     cellSize: 0.16666667
     manualTileSize: 0
     tileSize: 256
-    accuratePlacement: 0
+    buildHeightMesh: 0
     maxJobWorkers: 0
     preserveTilesOutsideBounds: 0
     debug:
@@ -163,9 +159,17 @@ Camera:
   m_projectionMatrixMode: 1
   m_GateFitMode: 2
   m_FOVAxisMode: 0
+  m_Iso: 200
+  m_ShutterSpeed: 0.005
+  m_Aperture: 16
+  m_FocusDistance: 10
+  m_FocalLength: 50
+  m_BladeCount: 5
+  m_Curvature: {x: 2, y: 11}
+  m_BarrelClipping: 0.25
+  m_Anamorphism: 0
   m_SensorSize: {x: 36, y: 24}
   m_LensShift: {x: 0, y: 0}
-  m_FocalLength: 50
   m_NormalizedViewPortRect:
     serializedVersion: 2
     x: 0
@@ -199,13 +203,13 @@ Transform:
   m_PrefabInstance: {fileID: 0}
   m_PrefabAsset: {fileID: 0}
   m_GameObject: {fileID: 126803971}
+  serializedVersion: 2
   m_LocalRotation: {x: 0, y: 0, z: 0, w: 1}
   m_LocalPosition: {x: 0, y: 1, z: -10}
   m_LocalScale: {x: 1, y: 1, z: 1}
   m_ConstrainProportionsScale: 0
   m_Children: []
   m_Father: {fileID: 0}
-  m_RootOrder: 0
   m_LocalEulerAnglesHint: {x: 0, y: 0, z: 0}
 --- !u!1 &586792171
 GameObject:
@@ -326,13 +330,70 @@ Transform:
   m_PrefabInstance: {fileID: 0}
   m_PrefabAsset: {fileID: 0}
   m_GameObject: {fileID: 586792171}
+  serializedVersion: 2
+  m_LocalRotation: {x: 0, y: 0, z: 0, w: 1}
+  m_LocalPosition: {x: 0, y: 0, z: 0}
+  m_LocalScale: {x: 1, y: 1, z: 1}
+  m_ConstrainProportionsScale: 0
+  m_Children: []
+  m_Father: {fileID: 0}
+  m_LocalEulerAnglesHint: {x: 0, y: 0, z: 0}
+--- !u!1 &994260143
+GameObject:
+  m_ObjectHideFlags: 0
+  m_CorrespondingSourceObject: {fileID: 0}
+  m_PrefabInstance: {fileID: 0}
+  m_PrefabAsset: {fileID: 0}
+  serializedVersion: 6
+  m_Component:
+  - component: {fileID: 994260145}
+  - component: {fileID: 994260144}
+  m_Layer: 0
+  m_Name: Example_Generics
+  m_TagString: Untagged
+  m_Icon: {fileID: 0}
+  m_NavMeshLayer: 0
+  m_StaticEditorFlags: 0
+  m_IsActive: 1
+--- !u!114 &994260144
+MonoBehaviour:
+  m_ObjectHideFlags: 0
+  m_CorrespondingSourceObject: {fileID: 0}
+  m_PrefabInstance: {fileID: 0}
+  m_PrefabAsset: {fileID: 0}
+  m_GameObject: {fileID: 994260143}
+  m_Enabled: 1
+  m_EditorHideFlags: 0
+  m_Script: {fileID: 11500000, guid: dff76005e1dfac84287448b12c4b160e, type: 3}
+  m_Name: 
+  m_EditorClassIdentifier: 
+  contravarianceActions:
+  - rid: 3354424774140624943
+  covarianceActions:
+  - rid: 3354424774140624944
+  references:
+    version: 2
+    RefIds:
+    - rid: 3354424774140624943
+      type: {class: DerivedAction1, ns: , asm: Assembly-CSharp}
+      data: 
+    - rid: 3354424774140624944
+      type: {class: NetworkActorAction1, ns: , asm: Assembly-CSharp}
+      data: 
+--- !u!4 &994260145
+Transform:
+  m_ObjectHideFlags: 0
+  m_CorrespondingSourceObject: {fileID: 0}
+  m_PrefabInstance: {fileID: 0}
+  m_PrefabAsset: {fileID: 0}
+  m_GameObject: {fileID: 994260143}
+  serializedVersion: 2
   m_LocalRotation: {x: 0, y: 0, z: 0, w: 1}
   m_LocalPosition: {x: 0, y: 0, z: 0}
   m_LocalScale: {x: 1, y: 1, z: 1}
   m_ConstrainProportionsScale: 0
   m_Children: []
   m_Father: {fileID: 0}
-  m_RootOrder: 2
   m_LocalEulerAnglesHint: {x: 0, y: 0, z: 0}
 --- !u!1 &1127138992
 GameObject:
@@ -359,9 +420,8 @@ Light:
   m_PrefabAsset: {fileID: 0}
   m_GameObject: {fileID: 1127138992}
   m_Enabled: 1
-  serializedVersion: 10
+  serializedVersion: 11
   m_Type: 1
-  m_Shape: 0
   m_Color: {r: 1, g: 0.95686275, b: 0.8392157, a: 1}
   m_Intensity: 1
   m_Range: 10
@@ -420,11 +480,19 @@ Transform:
   m_PrefabInstance: {fileID: 0}
   m_PrefabAsset: {fileID: 0}
   m_GameObject: {fileID: 1127138992}
+  serializedVersion: 2
   m_LocalRotation: {x: 0.40821788, y: -0.23456968, z: 0.10938163, w: 0.8754261}
   m_LocalPosition: {x: 0, y: 3, z: 0}
   m_LocalScale: {x: 1, y: 1, z: 1}
   m_ConstrainProportionsScale: 0
   m_Children: []
   m_Father: {fileID: 0}
-  m_RootOrder: 1
   m_LocalEulerAnglesHint: {x: 50, y: -30, z: 0}
+--- !u!1660057539 &9223372036854775807
+SceneRoots:
+  m_ObjectHideFlags: 0
+  m_Roots:
+  - {fileID: 126803974}
+  - {fileID: 1127138994}
+  - {fileID: 586792173}
+  - {fileID: 994260145}

Assets/Example/Example_Generics.cs

@@ -0,0 +1,93 @@
+using System;
+using System.Collections.Generic;
+using UnityEngine;
+
+public interface IActor { }
+public interface IStandardActor : IActor { }
+public interface INetworkActor : IActor { }
+
+public interface IContravarianceAction<in T> where T : IActor {
+	void DoAction (T actor);
+}
+
+public interface ICovarianceAction<out T> where T : IActor
+{
+	T Actor { get; }
+}
+
+public interface IActorAction : IContravarianceAction<IActor>, ICovarianceAction<IActor> { }
+public interface IStandardActorAction : IContravarianceAction<IStandardActor>, ICovarianceAction<IStandardActor> { }
+public interface INetworkActorAction : IContravarianceAction<INetworkActor>, ICovarianceAction<INetworkActor> { }
+
+[Serializable]
+public sealed class StandardActorAction : IContravarianceAction<IStandardActor>, ICovarianceAction<IStandardActor>
+{
+	public void DoAction (IStandardActor actor)
+	{
+	}
+	public IStandardActor Actor => null;
+}
+
+[Serializable]
+public sealed class ActorAction : IContravarianceAction<IActor>, ICovarianceAction<IActor>
+{
+	public void DoAction (IActor actor)
+	{
+	}
+	public IActor Actor => null;
+}
+
+[Serializable]
+public abstract class BaseAction<T> : IContravarianceAction<T>, ICovarianceAction<T> where T : IActor
+{
+	public void DoAction (T actor) {
+	}
+	public T Actor => default;
+}
+
+[Serializable]
+public sealed class DerivedAction1 : BaseAction<IActor> { }
+
+[Serializable]
+public sealed class DerivedAction2 : BaseAction<INetworkActor> { }
+
+[Serializable]
+public sealed class DerivedAction3 : BaseAction<IStandardActor> { }
+
+[Serializable]
+public sealed class NetworkActorAction1 : INetworkActorAction
+{
+	public void DoAction (INetworkActor actor)
+	{
+	}
+	public INetworkActor Actor => null;
+}
+
+[Serializable]
+public sealed class NetworkActorAction2 : IContravarianceAction<INetworkActor>, ICovarianceAction<INetworkActor>
+{
+	public void DoAction (INetworkActor actor)
+	{
+	}
+	public INetworkActor Actor => null;
+}
+
+[Serializable]
+public sealed class NetworkActorAction3 : IContravarianceAction<IActor>, ICovarianceAction<IActor>
+{
+	public void DoAction (IActor actor)
+	{
+	}
+	public IActor Actor => null;
+}
+
+public class Example_Generics : MonoBehaviour
+{
+
+	[SerializeReference, SubclassSelector]
+	public List<IContravarianceAction<INetworkActor>> contravarianceActions = new List<IContravarianceAction<INetworkActor>>();
+
+	[SerializeReference, SubclassSelector]
+	public List<ICovarianceAction<INetworkActor>> covarianceActions = new List<ICovarianceAction<INetworkActor>>();
+
+}

Assets/Example/Example_Generics.cs.meta

@@ -0,0 +1,11 @@
+fileFormatVersion: 2
+guid: dff76005e1dfac84287448b12c4b160e
+MonoImporter:
+  externalObjects: {}
+  serializedVersion: 2
+  defaultReferences: []
+  executionOrder: 0
+  icon: {instanceID: 0}
+  userData: 
+  assetBundleName: 
+  assetBundleVariant: 

Assets/MackySoft/MackySoft.SerializeReferenceExtensions/Editor/AdvancedTypePopup.cs

@@ -1,5 +1,4 @@
-#if UNITY_2019_3_OR_NEWER
+using System;
-using System;
 using System.Linq;
 using System.Collections.Generic;
 using UnityEngine;
@@ -138,4 +137,3 @@ namespace MackySoft.SerializeReferenceExtensions.Editor {
 
 	}
 }
-#endif

Assets/MackySoft/MackySoft.SerializeReferenceExtensions/Editor/MackySoft.SerializeReferenceExtensions.Editor.asmdef

@@ -12,9 +12,7 @@
     "overrideReferences": false,
     "precompiledReferences": [],
     "autoReferenced": true,
-    "defineConstraints": [
+    "defineConstraints": [],
-        "UNITY_2019_3_OR_NEWER"
-    ],
     "versionDefines": [],
     "noEngineReferences": false
 }

Assets/MackySoft/MackySoft.SerializeReferenceExtensions/Editor/ManagedReferenceContextualPropertyMenu.cs

@@ -1,16 +1,20 @@
-#if UNITY_2019_3_OR_NEWER
+// NOTE: managedReferenceValue getter is available only in Unity 2021.3 or later.
+#if UNITY_2021_3_OR_NEWER
+using System;
 using UnityEditor;
 using UnityEngine;
 
 namespace MackySoft.SerializeReferenceExtensions.Editor
 {
-	public static class CopyAndPasteProperty
+	public static class ManagedReferenceContextualPropertyMenu
 	{
 
 		const string kCopiedPropertyPathKey = "SerializeReferenceExtensions.CopiedPropertyPath";
 		const string kClipboardKey = "SerializeReferenceExtensions.CopyAndPasteProperty";
 
 		static readonly GUIContent kPasteContent = new GUIContent("Paste Property");
+		static readonly GUIContent kNewInstanceContent = new GUIContent("New Instance");
+		static readonly GUIContent kResetAndNewInstanceContent = new GUIContent("Reset and New Instance");
 
 		[InitializeOnLoadMethod]
 		static void Initialize ()
@@ -37,6 +41,20 @@ namespace MackySoft.SerializeReferenceExtensions.Editor
 				{
 					menu.AddDisabledItem(kPasteContent);
 				}
+
+				menu.AddSeparator("");
+
+				bool hasInstance = clonedProperty.managedReferenceValue != null;
+				if (hasInstance)
+				{
+					menu.AddItem(kNewInstanceContent, false, NewInstance, clonedProperty);
+					menu.AddItem(kResetAndNewInstanceContent, false, ResetAndNewInstance, clonedProperty);
+				}
+				else
+				{
+					menu.AddDisabledItem(kNewInstanceContent);
+					menu.AddDisabledItem(kResetAndNewInstanceContent);
+				}
 			}
 		}
 
@@ -61,6 +79,29 @@ namespace MackySoft.SerializeReferenceExtensions.Editor
 			JsonUtility.FromJsonOverwrite(json, property.managedReferenceValue);
 			property.serializedObject.ApplyModifiedProperties();
 		}
+
+		static void NewInstance (object customData)
+		{
+			SerializedProperty property = (SerializedProperty)customData;
+			string json = JsonUtility.ToJson(property.managedReferenceValue);
+
+			Undo.RecordObject(property.serializedObject.targetObject, "New Instance");
+			property.managedReferenceValue = JsonUtility.FromJson(json, property.managedReferenceValue.GetType());
+			property.serializedObject.ApplyModifiedProperties();
+
+			Debug.Log($"Create new instance of \"{property.propertyPath}\".");
+		}
+
+		static void ResetAndNewInstance (object customData)
+		{
+			SerializedProperty property = (SerializedProperty)customData;
+
+			Undo.RecordObject(property.serializedObject.targetObject, "Reset and New Instance");
+			property.managedReferenceValue = Activator.CreateInstance(property.managedReferenceValue.GetType());
+			property.serializedObject.ApplyModifiedProperties();
+
+			Debug.Log($"Reset property and created new instance of \"{property.propertyPath}\".");
+		}
 	}
 }
 #endif

Assets/MackySoft/MackySoft.SerializeReferenceExtensions/Editor/ManagedReferenceUtility.cs

@@ -1,21 +1,27 @@
-#if UNITY_2019_3_OR_NEWER
+using System;
-using System;
 using System.Reflection;
 using UnityEditor;
 using UnityEngine;
 
-namespace MackySoft.SerializeReferenceExtensions.Editor {
+namespace MackySoft.SerializeReferenceExtensions.Editor
+{
+
 	public static class ManagedReferenceUtility {
 
 		public static object SetManagedReference (this SerializedProperty property,Type type) {
-			object result;
+			object result = null;
-			if (property.managedReferenceValue != null)
+
+#if UNITY_2021_3_OR_NEWER
+			// NOTE: managedReferenceValue getter is available only in Unity 2021.3 or later.
+			if ((type != null) && (property.managedReferenceValue != null))
 			{
 				// Restore an previous values from json.
 				string json = JsonUtility.ToJson(property.managedReferenceValue);
 				result = JsonUtility.FromJson(json, type);
 			}
-			else
+#endif
+
+			if (result == null)
 			{
 				result = (type != null) ? Activator.CreateInstance(type) : null;
 			}
@@ -38,4 +44,3 @@ namespace MackySoft.SerializeReferenceExtensions.Editor {
 
 	}
 }
-#endif

Assets/MackySoft/MackySoft.SerializeReferenceExtensions/Editor/PropertyDrawerCache.cs

@@ -1,5 +1,4 @@
-#if UNITY_2019_3_OR_NEWER
+using System;
-using System;
 using System.Collections.Generic;
 using UnityEditor;
 using System.Reflection;
@@ -25,9 +24,10 @@ namespace MackySoft.SerializeReferenceExtensions.Editor
 
 		static Type GetCustomPropertyDrawerType (Type type)
 		{
-			foreach (Assembly assembly in AppDomain.CurrentDomain.GetAssemblies())
+			Type[] interfaceTypes = type.GetInterfaces();
-			{
+
-				foreach (Type drawerType in assembly.GetTypes())
+			var types = TypeCache.GetTypesWithAttribute<CustomPropertyDrawer>();
+			foreach (Type drawerType in types)
 			{
 				var customPropertyDrawerAttributes = drawerType.GetCustomAttributes(typeof(CustomPropertyDrawer), true);
 				foreach (CustomPropertyDrawer customPropertyDrawer in customPropertyDrawerAttributes)
@@ -36,10 +36,39 @@ namespace MackySoft.SerializeReferenceExtensions.Editor
 					if (field != null)
 					{
 						var fieldType = field.GetValue(customPropertyDrawer) as Type;
-							if (fieldType != null && fieldType == type)
+						if (fieldType != null)
+						{
+							if (fieldType == type)
 							{
 								return drawerType;
 							}
+							
+							// If the property drawer also allows for being applied to child classes, check if they match
+							var useForChildrenField = customPropertyDrawer.GetType().GetField("m_UseForChildren", BindingFlags.NonPublic | BindingFlags.Instance);
+							if (useForChildrenField != null)
+							{
+								object useForChildrenValue = useForChildrenField.GetValue(customPropertyDrawer);
+								if (useForChildrenValue is bool && (bool)useForChildrenValue)
+								{
+									// Check interfaces
+									if (Array.Exists(interfaceTypes, interfaceType => interfaceType == fieldType))
+									{
+										return drawerType;
+									}
+
+									// Check derived types
+									Type baseType = type.BaseType;
+									while (baseType != null)
+									{
+										if (baseType == fieldType)
+										{
+											return drawerType;
+										}
+
+										baseType = baseType.BaseType;
+									}
+								}
+							}
 						}
 					}
 				}
@@ -49,4 +78,3 @@ namespace MackySoft.SerializeReferenceExtensions.Editor
 
 	}
 }
-#endif

Assets/MackySoft/MackySoft.SerializeReferenceExtensions/Editor/SerializedPropertyExtensions.cs

@@ -0,0 +1,29 @@
+using System.Collections.Generic;
+using UnityEditor;
+
+namespace MackySoft.SerializeReferenceExtensions.Editor
+{
+	public static class SerializedPropertyExtensions
+	{
+		public static IEnumerable<SerializedProperty> GetChildProperties (this SerializedProperty parent, int depth = 1)
+		{
+			parent = parent.Copy();
+
+			int depthOfParent = parent.depth;
+			var enumerator = parent.GetEnumerator();
+
+			while (enumerator.MoveNext())
+			{
+				if (enumerator.Current is not SerializedProperty childProperty)
+				{
+					continue;
+				}
+				if (childProperty.depth > (depthOfParent + depth))
+				{
+					continue;
+				}
+				yield return childProperty.Copy();
+			}
+		}
+	}
+}

Assets/MackySoft/MackySoft.SerializeReferenceExtensions/Editor/SerializedPropertyExtensions.cs.meta

@@ -0,0 +1,11 @@
+fileFormatVersion: 2
+guid: b934aeca38cb7a24cabd6047fe0e298a
+MonoImporter:
+  externalObjects: {}
+  serializedVersion: 2
+  defaultReferences: []
+  executionOrder: 0
+  icon: {instanceID: 0}
+  userData: 
+  assetBundleName: 
+  assetBundleVariant: 

Assets/MackySoft/MackySoft.SerializeReferenceExtensions/Editor/SubclassSelectorDrawer.cs

@@ -1,5 +1,4 @@
-#if UNITY_2019_3_OR_NEWER
+using System;
-using System;
 using System.Linq;
 using System.Collections.Generic;
 using UnityEngine;
@@ -22,7 +21,7 @@ namespace MackySoft.SerializeReferenceExtensions.Editor
 		}
 
 		const int k_MaxTypePopupLineCount = 13;
-		static readonly Type k_UnityObjectType = typeof(UnityEngine.Object);
+		
 		static readonly GUIContent k_NullDisplayName = new GUIContent(TypeMenuUtility.k_NullDisplayName);
 		static readonly GUIContent k_IsNotManagedReferenceLabel = new GUIContent("The property type is not manage reference.");
 
@@ -31,49 +30,101 @@ namespace MackySoft.SerializeReferenceExtensions.Editor
 
 		SerializedProperty m_TargetProperty;
 
-		public override void OnGUI (Rect position,SerializedProperty property,GUIContent label) {
+		public override void OnGUI (Rect position, SerializedProperty property, GUIContent label)
-			EditorGUI.BeginProperty(position,label,property);
+		{
+			EditorGUI.BeginProperty(position, label, property);
+
+			if (property.propertyType == SerializedPropertyType.ManagedReference)
+			{
+				// Render label first to avoid label overlap for lists
+				Rect foldoutLabelRect = new Rect(position);
+				foldoutLabelRect.height = EditorGUIUtility.singleLineHeight;
+				foldoutLabelRect = EditorGUI.IndentedRect(foldoutLabelRect);
+				Rect popupPosition = EditorGUI.PrefixLabel(foldoutLabelRect, label);
+
+#if UNITY_2021_3_OR_NEWER
+				// Override the label text with the ToString() of the managed reference.
+				var subclassSelectorAttribute = (SubclassSelectorAttribute)attribute;
+				if (subclassSelectorAttribute.UseToStringAsLabel && !property.hasMultipleDifferentValues)
+				{
+					object managedReferenceValue = property.managedReferenceValue;
+					if (managedReferenceValue != null)
+					{
+						label.text = managedReferenceValue.ToString();
+					}
+				}
+#endif
 
-			if (property.propertyType == SerializedPropertyType.ManagedReference) {
 				// Draw the subclass selector popup.
-				Rect popupPosition = new Rect(position);
+				if (EditorGUI.DropdownButton(popupPosition, GetTypeName(property), FocusType.Keyboard))
-				popupPosition.width -= EditorGUIUtility.labelWidth;
+				{
-				popupPosition.x += EditorGUIUtility.labelWidth;
-				popupPosition.height = EditorGUIUtility.singleLineHeight;
-
-				if (EditorGUI.DropdownButton(popupPosition,GetTypeName(property),FocusType.Keyboard)) {
 					TypePopupCache popup = GetTypePopup(property);
 					m_TargetProperty = property;
 					popup.TypePopup.Show(popupPosition);
 				}
 
+				// Draw the foldout.
+				if (!string.IsNullOrEmpty(property.managedReferenceFullTypename))
+				{
+					Rect foldoutRect = new Rect(position);
+					foldoutRect.height = EditorGUIUtility.singleLineHeight;
+
+#if UNITY_2022_2_OR_NEWER && !UNITY_6000_0_OR_NEWER
+					// NOTE: Position x must be adjusted.
+					// FIXME: Is there a more essential solution...?
+					// The most promising is UI Toolkit, but it is currently unable to reproduce all of SubclassSelector features. (Complete provision of contextual menu, e.g.)
+					// 2021.3: No adjustment
+					// 2022.1: No adjustment
+					// 2022.2: Adjustment required
+					// 2022.3: Adjustment required
+					// 2023.1: Adjustment required
+					// 2023.2: Adjustment required
+					// 6000.0: No adjustment
+					foldoutRect.x -= 12;
+#endif
+
+					property.isExpanded = EditorGUI.Foldout(foldoutRect, property.isExpanded, GUIContent.none, true);
+				}
+
+				// Draw property if expanded.
+				if (property.isExpanded)
+				{
+					using (new EditorGUI.IndentLevelScope())
+					{
 						// Check if a custom property drawer exists for this type.
 						PropertyDrawer customDrawer = GetCustomPropertyDrawer(property);
 						if (customDrawer != null)
 						{
 							// Draw the property with custom property drawer.
-					Rect foldoutRect = new Rect(position);
-					foldoutRect.height = EditorGUIUtility.singleLineHeight;
-					property.isExpanded = EditorGUI.Foldout(foldoutRect, property.isExpanded, label, true);
-					
-					if (property.isExpanded)
-					{
-						using (new EditorGUI.IndentLevelScope())
-						{
 							Rect indentedRect = position;
 							float foldoutDifference = EditorGUIUtility.singleLineHeight + EditorGUIUtility.standardVerticalSpacing;
 							indentedRect.height = customDrawer.GetPropertyHeight(property, label);
 							indentedRect.y += foldoutDifference;
 							customDrawer.OnGUI(indentedRect, property, label);
 						}
+						else
+						{
+							// Draw the properties of the child elements.
+							// NOTE: In the following code, since the foldout layout isn't working properly, I'll iterate through the properties of the child elements myself.
+							// EditorGUI.PropertyField(position, property, GUIContent.none, true);
+
+							Rect childPosition = position;
+							childPosition.y += EditorGUIUtility.singleLineHeight + EditorGUIUtility.standardVerticalSpacing;
+							foreach (SerializedProperty childProperty in property.GetChildProperties())
+							{
+								float height = EditorGUI.GetPropertyHeight(childProperty, new GUIContent(childProperty.displayName, childProperty.tooltip), true);
+								childPosition.height = height;
+								EditorGUI.PropertyField(childPosition, childProperty, true);
+
+								childPosition.y += height + EditorGUIUtility.standardVerticalSpacing;
+							}
+						}
+					}
 				}
 			}
 			else
 			{
-					EditorGUI.PropertyField(position, property, label, true);
+				EditorGUI.LabelField(position, label, k_IsNotManagedReferenceLabel);
-				}
-			} else {
-				EditorGUI.LabelField(position,label,k_IsNotManagedReferenceLabel);
 			}
 
 			EditorGUI.EndProperty();
@@ -98,13 +149,7 @@ namespace MackySoft.SerializeReferenceExtensions.Editor
 
 				Type baseType = ManagedReferenceUtility.GetType(managedReferenceFieldTypename);
 				var popup = new AdvancedTypePopup(
-					TypeCache.GetTypesDerivedFrom(baseType).Append(baseType).Where(p =>
+					TypeSearch.GetTypes(baseType),
-						(p.IsPublic || p.IsNestedPublic) &&
-						!p.IsAbstract &&
-						!p.IsGenericType &&
-						!k_UnityObjectType.IsAssignableFrom(p) &&
-						Attribute.IsDefined(p,typeof(SerializableAttribute))
-					),
 					k_MaxTypePopupLineCount,
 					state
 				);
@@ -115,7 +160,6 @@ namespace MackySoft.SerializeReferenceExtensions.Editor
 					foreach (var targetObject in m_TargetProperty.serializedObject.targetObjects) {
 						SerializedObject individualObject = new SerializedObject(targetObject);
 						SerializedProperty individualProperty = individualObject.FindProperty(m_TargetProperty.propertyPath);
-
 						object obj = individualProperty.SetManagedReference(type);
 						individualProperty.isExpanded = (obj != null);
 
@@ -175,4 +219,3 @@ namespace MackySoft.SerializeReferenceExtensions.Editor
 
 	}
 }
-#endif

Assets/MackySoft/MackySoft.SerializeReferenceExtensions/Editor/TypeMenuUtility.cs

@@ -1,9 +1,10 @@
-#if UNITY_2019_3_OR_NEWER
+using System;
-using System;
 using System.Linq;
 using System.Collections.Generic;
+using UnityEditor;
 
-namespace MackySoft.SerializeReferenceExtensions.Editor {
+namespace MackySoft.SerializeReferenceExtensions.Editor
+{
 	public static class TypeMenuUtility {
 
 		public const string k_NullDisplayName = "<null>";
@@ -42,4 +43,3 @@ namespace MackySoft.SerializeReferenceExtensions.Editor {
 
 	}
 }
-#endif

Assets/MackySoft/MackySoft.SerializeReferenceExtensions/Editor/TypeSearch.cs

@@ -0,0 +1,142 @@
+using System;
+using System.Linq;
+using System.Collections.Generic;
+using UnityEditor;
+using System.Reflection;
+
+namespace MackySoft.SerializeReferenceExtensions.Editor
+{
+	public static class TypeSearch
+	{
+
+#if UNITY_2023_2_OR_NEWER
+		static readonly Dictionary<Type, List<Type>> m_TypeCache = new Dictionary<Type, List<Type>>();
+#endif
+
+		public static IEnumerable<Type> GetTypes (Type baseType)
+		{
+#if UNITY_2023_2_OR_NEWER
+			// NOTE: This is a generics solution for Unity 2023.2 and later.
+			// 2023.2 because SerializeReference supports generic type instances and because the behaviour is stable.
+			if (baseType.IsGenericType)
+			{
+				return GetTypesWithGeneric(baseType);
+			}
+			else
+			{
+				return GetTypesUsingTypeCache(baseType);
+			}
+#else
+			return GetTypesUsingTypeCache(baseType);
+#endif
+		}
+
+		static IEnumerable<Type> GetTypesUsingTypeCache (Type baseType)
+		{
+			return TypeCache.GetTypesDerivedFrom(baseType)
+				.Append(baseType)
+				.Where(IsValidType);
+		}
+
+#if UNITY_2023_2_OR_NEWER
+		static IEnumerable<Type> GetTypesWithGeneric (Type baseType)
+		{
+			if (m_TypeCache.TryGetValue(baseType, out List<Type> result))
+			{
+				return result;
+			}
+
+			result = new List<Type>();
+			Type genericTypeDefinition = null;
+			Type[] targetTypeArguments = null;
+			Type[] genericTypeParameters = null;
+
+			if (baseType.IsGenericType)
+			{
+				genericTypeDefinition = baseType.GetGenericTypeDefinition();
+				targetTypeArguments = baseType.GetGenericArguments();
+				genericTypeParameters = genericTypeDefinition.GetGenericArguments();
+			}
+			else
+			{
+				genericTypeDefinition = baseType;
+				targetTypeArguments = Type.EmptyTypes;
+				genericTypeParameters = Type.EmptyTypes;
+			}
+
+			IEnumerable<Type> types = AppDomain.CurrentDomain.GetAssemblies()
+				.SelectMany(x => x.GetTypes())
+				.Where(IsValidType);
+
+			foreach (Type type in types)
+			{
+				Type[] interfaceTypes = type.GetInterfaces();
+				foreach (Type interfaceType in interfaceTypes)
+				{
+					if (!interfaceType.IsGenericType || interfaceType.GetGenericTypeDefinition() != genericTypeDefinition)
+					{
+						continue;
+					}
+
+					Type[] sourceTypeArguments = interfaceType.GetGenericArguments();
+
+					bool allParametersMatch = true;
+
+					for (int i = 0; i < genericTypeParameters.Length; i++)
+					{
+						var variance = genericTypeParameters[i].GenericParameterAttributes & GenericParameterAttributes.VarianceMask;
+
+						Type sourceTypeArgument = sourceTypeArguments[i];
+						Type targetTypeArgument = targetTypeArguments[i];
+
+						if (variance == GenericParameterAttributes.Contravariant)
+						{
+							if (!sourceTypeArgument.IsAssignableFrom(targetTypeArgument))
+							{
+								allParametersMatch = false;
+								break;
+							}
+						}
+						else if (variance == GenericParameterAttributes.Covariant)
+						{
+							if (!targetTypeArgument.IsAssignableFrom(sourceTypeArgument))
+							{
+								allParametersMatch = false;
+								break;
+							}
+						}
+						else
+						{
+							if (sourceTypeArgument != targetTypeArgument)
+							{
+								allParametersMatch = false;
+								break;
+							}
+						}
+					}
+
+					if (allParametersMatch)
+					{
+						result.Add(type);
+						break;
+					}
+				}
+			}
+
+			m_TypeCache.Add(baseType, result);
+			return result;
+		}
+#endif
+
+		static bool IsValidType (Type type)
+		{
+			return
+				(type.IsPublic || type.IsNestedPublic || type.IsNestedPrivate) &&
+				!type.IsAbstract &&
+				!type.IsGenericType &&
+				!typeof(UnityEngine.Object).IsAssignableFrom(type) &&
+				Attribute.IsDefined(type, typeof(SerializableAttribute)) &&
+				!Attribute.IsDefined(type, typeof(HideInTypeMenuAttribute));
+		}
+	}
+}

Assets/MackySoft/MackySoft.SerializeReferenceExtensions/Editor/TypeSearch.cs.meta

@@ -0,0 +1,2 @@
+fileFormatVersion: 2
+guid: 5ea24172520aa2646954c1d246e7ba5d

Assets/MackySoft/MackySoft.SerializeReferenceExtensions/Runtime/AddTypeMenuAttribute.cs

@@ -1,6 +1,4 @@
-#if UNITY_2019_3_OR_NEWER
+using System;
-
-using System;
 	
 /// <summary>
 /// An attribute that overrides the name of the type displayed in the SubclassSelector popup.
@@ -35,4 +33,3 @@ public sealed class AddTypeMenuAttribute : Attribute {
 	}
 
 }
-#endif

Assets/MackySoft/MackySoft.SerializeReferenceExtensions/Runtime/HideInTypeMenuAttribute.cs

@@ -0,0 +1,9 @@
+using System;
+
+/// <summary>
+/// An attribute that hides the type in the SubclassSelector.
+/// </summary>
+[AttributeUsage(AttributeTargets.Class | AttributeTargets.Struct | AttributeTargets.Enum | AttributeTargets.Interface, AllowMultiple = false, Inherited = false)]
+public sealed class HideInTypeMenuAttribute : Attribute {
+
+}

Assets/MackySoft/MackySoft.SerializeReferenceExtensions/Runtime/HideInTypeMenuAttribute.cs.meta

@@ -0,0 +1,11 @@
+fileFormatVersion: 2
+guid: 9f48f5d86a108b94a9c26381f5ce678c
+MonoImporter:
+  externalObjects: {}
+  serializedVersion: 2
+  defaultReferences: []
+  executionOrder: 0
+  icon: {instanceID: 0}
+  userData: 
+  assetBundleName: 
+  assetBundleVariant: 

Assets/MackySoft/MackySoft.SerializeReferenceExtensions/Runtime/MackySoft.SerializeReferenceExtensions.asmdef

@@ -8,9 +8,7 @@
     "overrideReferences": false,
     "precompiledReferences": [],
     "autoReferenced": true,
-    "defineConstraints": [
+    "defineConstraints": [],
-        "UNITY_2019_3_OR_NEWER"
-    ],
     "versionDefines": [],
     "noEngineReferences": false
 }

Assets/MackySoft/MackySoft.SerializeReferenceExtensions/Runtime/SubclassSelectorAttribute.cs

@@ -1,12 +1,16 @@
-#if UNITY_2019_3_OR_NEWER
+using System;
-using System;
 using UnityEngine;
 
 /// <summary>
 /// Attribute to specify the type of the field serialized by the SerializeReference attribute in the inspector.
 /// </summary>
-[AttributeUsage(AttributeTargets.Field,AllowMultiple = false)]
+[AttributeUsage(AttributeTargets.Field, AllowMultiple = false)]
-public sealed class SubclassSelectorAttribute : PropertyAttribute {
+public sealed class SubclassSelectorAttribute : PropertyAttribute
+{
+
+#if UNITY_2021_3_OR_NEWER
+	// NOTE: Use managedReferenceValue getter to invoke instance method in SubclassSelectorDrawer.
+	public bool UseToStringAsLabel { get; set; }
+#endif
 
 }
-#endif

Assets/MackySoft/MackySoft.SerializeReferenceExtensions/package.json

@@ -2,7 +2,7 @@
 	"name": "com.mackysoft.serializereference-extensions",
 	"displayName": "SerializeReference Extensions",
 	"author": { "name": "MackySoft", "url": "https://github.com/mackysoft" },
-	"version": "1.2.0",
+	"version": "1.6.0",
 	"unity": "2021.3",
 	"description": "Provide popup to specify the type of the field serialized by the [SerializeReference] attribute in the inspector.",
 	"keywords": [ "SerializeReference", "Editor" ],

Packages/manifest.json

@@ -1,7 +1,7 @@
 {
   "dependencies": {
-    "com.unity.ide.rider": "3.0.24",
+    "com.unity.ide.rider": "3.0.28",
-    "com.unity.ide.visualstudio": "2.0.18",
+    "com.unity.ide.visualstudio": "2.0.22",
     "com.unity.ide.vscode": "1.2.5",
     "com.unity.test-framework": "1.1.33",
     "com.unity.modules.ai": "1.0.0",

Packages/packages-lock.json

@@ -8,7 +8,7 @@
       "url": "https://packages.unity.com"
     },
     "com.unity.ide.rider": {
-      "version": "3.0.24",
+      "version": "3.0.28",
       "depth": 0,
       "source": "registry",
       "dependencies": {
@@ -17,7 +17,7 @@
       "url": "https://packages.unity.com"
     },
     "com.unity.ide.visualstudio": {
-      "version": "2.0.18",
+      "version": "2.0.22",
       "depth": 0,
       "source": "registry",
       "dependencies": {

README.md

@@ -15,9 +15,19 @@ The `SubclassSelector` attribute allows you to easily set subclasses of those ab
 - Easily set subclass by popup.
 - **[New]** Type finding by fuzzy finder.
 - **[New]** Override the type name and path by the `AddTypeMenu` attribute.
+- **[New]** Available `CustomPropertyDrawer` for subclasses.
+- **[New]** Restore values of previous object from JSON when subclass is changed. (required Unity 2021.3 or later)
+- **[New]** Copy & Paste the subclass properties. (required Unity 2021.3 or later)
+- **[New]** Clear & reset the subclass properties. (required Unity 2021.3 or later)
+
+> See below for the reason for the limitation of versions less than Unity 2021.3.
+> 
+> https://blog.unity.com/engine-platform/serializereference-improvements-in-unity-2021-lts
 
 ## 📥 Installation
 
+#### Install via `.unitypackage`
+
 Download any version from releases.
 
 Releases: https://github.com/mackysoft/Unity-SerializeReferenceExtensions/releases
@@ -26,10 +36,17 @@ Releases: https://github.com/mackysoft/Unity-SerializeReferenceExtensions/releas
 
 Or, you can add this package by opening PackageManager and entering
 
-`https://github.com/mackysoft/Unity-SerializeReferenceExtensions.git?path=Assets/MackySoft/MackySoft.SerializeReferenceExtensions`
+```
+https://github.com/mackysoft/Unity-SerializeReferenceExtensions.git?path=Assets/MackySoft/MackySoft.SerializeReferenceExtensions
+```
 
 from the `Add package from git URL` option.
 
+If you are specifying a version, enter `#{VERSION}` at the end, as shown below.
+
+```
+https://github.com/mackysoft/Unity-SerializeReferenceExtensions.git?path=Assets/MackySoft/MackySoft.SerializeReferenceExtensions#1.1.9
+```
 
 #### Install via Open UPM
 
@@ -122,7 +139,7 @@ public struct StructCommand : ICommand {
 
 The `SubclassSelector` attribute supports types that meet the following conditions.
 
-- Public
+- Public or nested private
 - Not abstract
 - Not generic
 - Not unity object