Add events section to Expression-bodied members article (#41868)

* Add events section to Expression-bodied members article

* Update docs/csharp/programming-guide/statements-expressions-operators/expression-bodied-members.md

---------

Co-authored-by: Bill Wagner <[email protected]>

Author: YoshiRulz

docs/csharp/programming-guide/statements-expressions-operators/expression-bodied-members.md

@@ -57,6 +57,14 @@ You can use expression body definitions to implement property `get` and `set` ac
 
 For more information about properties, see [Properties (C# Programming Guide)](../classes-and-structs/properties.md).
 
+## Events
+
+Similarly, event `add` and `remove` accessors can be expression-bodied:
+
+[!code-csharp[expression-bodied-event-add-remove](../../../../samples/snippets/csharp/programming-guide/classes-and-structs/ExpressionBodiedMembers/expr-bodied-event.cs#1)]
+
+For more information about events, see [Events (C# Programming Guide)](../events/index.md).
+
 ## Constructors
 
 An expression body definition for a constructor typically consists of a single assignment expression or a method call that handles the constructor's arguments or initializes instance state.

samples/snippets/csharp/programming-guide/classes-and-structs/ExpressionBodiedMembers/expr-bodied-event.cs

@@ -0,0 +1,42 @@
+using System;
+
+namespace ExprBodied;
+
+// <Snippet1>
+public class ChangedEventArgs : EventArgs
+{
+   public required int NewValue { get; init; }
+}
+
+public class ObservableNum(int _value)
+{
+   public event EventHandler<ChangedEventArgs> ChangedGeneric = default!;
+
+   public event EventHandler Changed
+   {
+      // Note that, while this is syntactically valid, it won't work as expected because it's creating a new delegate object with each call.
+      add => ChangedGeneric += (sender, args) => value(sender, args);
+      remove => ChangedGeneric -= (sender, args) => value(sender, args);
+   }
+
+   public int Value
+   {
+      get => _value;
+      set => ChangedGeneric?.Invoke(this, new() { NewValue = (_value = value) });
+   }
+}
+// </Snippet1>
+
+public class ExpressionExample
+{
+   public static void Main()
+   {
+      void PrintingHandler(object? sender, object? args)
+         => Console.WriteLine((args as ChangedEventArgs)?.NewValue);
+      ObservableNum num = new(2);
+      num.Changed += PrintingHandler;
+      num.Value = 3;
+      num.Changed -= PrintingHandler;
+      num.Value = 1; // Still prints!
+   }
+}