Subscribe to fields instead of properties (#521)

Author: mrpmorris

Docs/releases.md

@@ -1,5 +1,8 @@
 # Releases
 
+## New in 6.5
+ * Support subscribing to fields instead of properties ([#514](https://github.com/mrpmorris/Fluxor/issues/514))
+
 ## New in 6.4
  * Optimise Roslyn analyzer
  * Use Microsoft.CodeAnalysis.CSharp instead of Microsoft.CodeAnalysis.CSharp.Workspaces

Source/Lib/Fluxor.UnitTests/StateSubscriberTests/SubscribeTests.cs

@@ -10,7 +10,7 @@ public class SubscribeTests
 
 	private int CallbackInvocationCount;
 	private string State = "X";
-	private IStateSelection<string, char?> Selection { get; }
+	private IStateSelection<string, char?> Selection;
 
 	[Fact]
 	public void WhenSubscribedToSubject_ThenNotificationsShouldBeReceived()

Source/Lib/Fluxor/StateSubscriber.cs

@@ -3,29 +3,23 @@
 using System.Collections.Generic;
 using System.Linq;
 using System.Reflection;
-using GetStateChangedPropertyDelegate = System.Func<object, Fluxor.IStateChangedNotifier>;
+using GetStateChangedFieldDelegate = System.Func<object, Fluxor.IStateChangedNotifier>;
 
 namespace Fluxor;
 
-/// <summary>
-/// A utility class that automatically subscribes to all <see cref="IStateChangedNotifier"/> properties
-/// on a specific object
-/// </summary>
 public static class StateSubscriber
 {
-	private static readonly ConcurrentDictionary<Type, IEnumerable<GetStateChangedPropertyDelegate>> ValueDelegatesByType;
+	private static readonly ConcurrentDictionary<Type, IEnumerable<GetStateChangedFieldDelegate>> ValueDelegatesByType;
 
 	static StateSubscriber()
-	{
-		ValueDelegatesByType = new ConcurrentDictionary<Type, IEnumerable<GetStateChangedPropertyDelegate>>();
-	}
+		=> ValueDelegatesByType = new ConcurrentDictionary<Type, IEnumerable<GetStateChangedFieldDelegate>>();
 
 	/// <summary>
-	/// Subscribes to all <see cref="IStateChangedNotifier"/> properties on the specified <paramref name="subject"/>
-	/// to ensure <paramref name="callback"/> is called whenever a state is modified
+	/// Subscribes to all <see cref="IStateChangedNotifier"/> fields on the specified <paramref name="subject"/>
+	/// to ensure <paramref name="callback"/> is called whenever a state is modified.
 	/// </summary>
-	/// <param name="subject">The object to scan for <see cref="IStateChangedNotifier"/> properties.</param>
-	/// <param name="callback">The action to execute when one of the states are modified</param>
+	/// <param name="subject">The object to scan for <see cref="IStateChangedNotifier"/> fields.</param>
+	/// <param name="callback">The action to execute when one of the states are modified.</param>
 	/// <returns></returns>
 	public static IDisposable Subscribe(object subject, Action<IStateChangedNotifier> callback)
 	{
@@ -34,14 +28,15 @@ public static IDisposable Subscribe(object subject, Action<IStateChangedNotifier
 		if (callback is null)
 			throw new ArgumentNullException(nameof(callback));
 
-		IEnumerable<GetStateChangedPropertyDelegate> getStateChangedNotifierPropertyDelegates =
-			GetStateChangedNotifierPropertyDelegatesForType(subject.GetType());
+		IEnumerable<GetStateChangedFieldDelegate> getStateChangedNotifierFieldDelegates =
+			GetStateChangedNotifierFieldDelegatesForType(subject.GetType());
+
 		var subscriptions = new List<(IStateChangedNotifier StateChangedNotifier, EventHandler Handler)>();
-		
-		foreach (GetStateChangedPropertyDelegate getStateChangedNotifierPropertyValue in getStateChangedNotifierPropertyDelegates)
+
+		foreach (GetStateChangedFieldDelegate getStateChangedNotifierFieldValue in getStateChangedNotifierFieldDelegates)
 		{
-			IStateChangedNotifier stateChangedNotifier = getStateChangedNotifierPropertyValue(subject);
-			var handler = new EventHandler((s, a) => callback(stateChangedNotifier));
+			IStateChangedNotifier stateChangedNotifier = getStateChangedNotifierFieldValue(subject);
+			var handler = new EventHandler((_, __) => callback(stateChangedNotifier));
 
 			subscriptions.Add((stateChangedNotifier, handler));
 			stateChangedNotifier.StateChanged += handler;
@@ -50,34 +45,32 @@ public static IDisposable Subscribe(object subject, Action<IStateChangedNotifier
 		return new DisposableCallback(
 			id: $"{nameof(StateSubscriber)}.{nameof(Subscribe)} / {subject.GetType().FullName}",
 			() =>
-				{
-					foreach (var subscription in subscriptions)
-						subscription.StateChangedNotifier.StateChanged -= subscription.Handler;
-				});
+			{
+				foreach (var subscription in subscriptions)
+					subscription.StateChangedNotifier.StateChanged -= subscription.Handler;
+			});
 	}
 
-	private static IEnumerable<PropertyInfo> GetStateChangedNotifierProperties(Type t) =>
+	private static IEnumerable<FieldInfo> GetStateChangedNotifierFields(Type t) =>
 		t == typeof(object)
-		? Enumerable.Empty<PropertyInfo>()
-		: GetStateChangedNotifierProperties(t.BaseType)
+		? Enumerable.Empty<FieldInfo>()
+		: GetStateChangedNotifierFields(t.BaseType)
 			.Union(
-				t.GetProperties(BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.DeclaredOnly)
-					.Where(p => typeof(IStateChangedNotifier).IsAssignableFrom(p.PropertyType))
+				t.GetFields(BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.DeclaredOnly)
+					.Where(f => typeof(IStateChangedNotifier).IsAssignableFrom(f.FieldType))
 			);
 
-	private static IEnumerable<GetStateChangedPropertyDelegate> GetStateChangedNotifierPropertyDelegatesForType(Type type)
+	private static IEnumerable<GetStateChangedFieldDelegate> GetStateChangedNotifierFieldDelegatesForType(Type type)
 	{
 		return ValueDelegatesByType.GetOrAdd(type, _ =>
 		{
-			var delegates = new List<GetStateChangedPropertyDelegate>();
-			IEnumerable<PropertyInfo> stateChangedNotifierProperties = GetStateChangedNotifierProperties(type);
+			var delegates = new List<GetStateChangedFieldDelegate>();
+			IEnumerable<FieldInfo> stateChangedNotifierFields = GetStateChangedNotifierFields(type);
 
-			foreach (PropertyInfo currentProperty in stateChangedNotifierProperties)
+			foreach (FieldInfo currentField in stateChangedNotifierFields)
 			{
-				Type getterMethod = typeof(Func<,>).MakeGenericType(type, currentProperty.PropertyType);
-				var stronglyTypedDelegate = Delegate.CreateDelegate(getterMethod, currentProperty.GetGetMethod(true));
-				var getValueDelegate = new GetStateChangedPropertyDelegate(
-					x => (IStateChangedNotifier)stronglyTypedDelegate.DynamicInvoke(x));
+				var getValueDelegate = new GetStateChangedFieldDelegate(
+					x => (IStateChangedNotifier)currentField.GetValue(x)!);
 				delegates.Add(getValueDelegate);
 			}