Proposal - Replace internal use of MessagingCenter

src/Compatibility/Core/src/iOS/Renderers/NavigationRenderer.cs

@@ -1712,5 +1712,5 @@ protected override void Dispose(bool disposing)
 		}
 	}
 
-	internal class UpdateToolBarButtonsMessage { }
+	internal sealed record UpdateToolBarButtonsMessage { }
 }

src/Controls/src/Core/HandlerImpl/Page.Impl.cs

@@ -80,5 +80,5 @@ internal NavigatedFromEventArgs(Page destinationPage)
 		internal Page DestinationPage { get; }
 	}
 
-	public class CloseContextActionsMessage { }
+	public sealed record CloseContextActionsMessage { }
 }

src/Controls/src/Core/IsExternalInit.cs

@@ -0,0 +1,9 @@
+// https://docs.microsoft.com/en-us/dotnet/api/system.runtime.compilerservices.isexternalinit?view=net-5.0
+// https://developercommunity.visualstudio.com/t/error-cs0518-predefined-type-systemruntimecompiler/1244809
+// Adding this because at least one of the target frameworks doesn't include it; hopefully we can drop this at some point
+// (and hopefully before release)
+// TODO ezhart Evaluate whether we still need this
+namespace System.Runtime.CompilerServices
+{
+	internal static class IsExternalInit { }
+}

src/Controls/src/Core/Page.cs

@@ -576,51 +576,12 @@ internal void SetTitleView(View oldTitleView, View newTitleView)
 	}
 
 	// TODO ezhart These Pages could probably all be IView
-	public class PageBusyMessage 
-	{
-		public PageBusyMessage(Page page, bool isBusy)
-		{
-			Page = page;
-			IsBusy = isBusy;
-		}
-
-		public Page Page { get; set; }
-		public bool IsBusy { get; set; }
-	}
-
-	public class PageAlertMessage
-	{
-		public PageAlertMessage(Page page, AlertArguments arguments)
-		{
-			Page = page;
-			Arguments = arguments;
-		}
-
-		public Page Page { get; set; }
-		public AlertArguments Arguments { get; set; }
-	}
+	public sealed record PageBusyMessage(Page Page, bool IsBusy);
 
-	public class PromptMessage 
-	{
-		public PromptMessage(Page page, PromptArguments arguments)
-		{
-			Page = page;
-			Arguments = arguments;
-		}
+	public sealed record PageAlertMessage(Page Page, AlertArguments Arguments);
 
-		public Page Page { get; set; }
-		public PromptArguments Arguments { get; set; }
-	}
-
-	public class ActionSheetMessage
-	{
-		public ActionSheetMessage(Page page, ActionSheetArguments arguments)
-		{
-			Page = page;
-			Arguments = arguments;
-		}
-
-		public Page Page { get; set; }
-		public ActionSheetArguments Arguments { get; set; }
-	}
+	public sealed record PromptMessage(Page Page, PromptArguments Arguments);
+
+	public sealed record ActionSheetMessage(Page Page, ActionSheetArguments Arguments);
 }
+

src/Controls/src/Core/RadioButtonGroupController.cs

@@ -134,7 +134,7 @@ void SetSelectedValue(object radioButtonValue)
 
 			if (radioButtonValue != null)
 			{
-				WeakReferenceMessenger.Default.Send(new RadioButtonGroupValueChanged(_groupName, RadioButtonGroup.GetVisualRoot(_layout), radioButtonValue));
+				WeakReferenceMessenger.Default.Send(new RadioButtonGroupValueChanged(RadioButtonGroup.GetVisualRoot(_layout), radioButtonValue, _groupName));
 			}
 		}
 

src/Controls/src/Core/RadioButtonMessages.cs

@@ -0,0 +1,16 @@
+namespace Microsoft.Maui.Controls
+{
+	internal abstract record RadioButtonScopeMessage(Element Scope);
+
+	internal sealed record RadioButtonGroupSelectionChanged(Element Scope, RadioButton RadioButton) 
+		: RadioButtonScopeMessage(Scope);
+
+	internal sealed record RadioButtonGroupNameChanged(Element Scope, string OldName) 
+		: RadioButtonScopeMessage(Scope);
+
+	internal sealed record RadioButtonValueChanged(Element Scope, RadioButton RadioButton)
+		: RadioButtonScopeMessage(Scope);
+
+	internal sealed record RadioButtonGroupValueChanged (Element Scope, object Value, string GroupName) 
+		: RadioButtonScopeMessage(Scope);
+}