Remove IAvaloniaPropertyVisitor due to generic virtual methods.

src/Avalonia.Base/AvaloniaObject.cs

@@ -646,10 +646,12 @@ protected internal virtual void LogBindingError(AvaloniaProperty property, Excep
         /// enabled.
         /// </summary>
         /// <param name="property">The property.</param>
-        /// <param name="value">The new binding value for the property.</param>
-        protected virtual void UpdateDataValidation<T>(
-            AvaloniaProperty<T> property,
-            BindingValue<T> value)
+        /// <param name="state">The current data binding state.</param>
+        /// <param name="error">The current data binding error, if any.</param>
+        protected virtual void UpdateDataValidation(
+            AvaloniaProperty property,
+            BindingValueType state,
+            Exception? error)
         {
         }
 
@@ -860,7 +862,7 @@ private void SetDirectValueUnchecked<T>(DirectPropertyBase<T> property, BindingV
 
             if (metadata.EnableDataValidation == true)
             {
-                UpdateDataValidation(property, value);
+                UpdateDataValidation(property, value.Type, value.Error);
             }
         }
 

src/Avalonia.Base/AvaloniaProperty.cs

@@ -2,6 +2,7 @@
 using System.Collections.Generic;
 using Avalonia.Data;
 using Avalonia.Data.Core;
+using Avalonia.Styling;
 using Avalonia.Utilities;
 
 namespace Avalonia
@@ -454,15 +455,6 @@ public override string ToString()
             return Name;
         }
 
-        /// <summary>
-        /// Uses the visitor pattern to resolve an untyped property to a typed property.
-        /// </summary>
-        /// <typeparam name="TData">The type of user data passed.</typeparam>
-        /// <param name="visitor">The visitor which will accept the typed property.</param>
-        /// <param name="data">The user data to pass.</param>
-        public abstract void Accept<TData>(IAvaloniaPropertyVisitor<TData> visitor, ref TData data)
-            where TData : struct;
-
         /// <summary>
         /// Routes an untyped ClearValue call to a typed call.
         /// </summary>
@@ -508,6 +500,7 @@ internal abstract IDisposable RouteBind(
             BindingPriority priority);
 
         internal abstract void RouteInheritanceParentChanged(AvaloniaObject o, AvaloniaObject? oldParent);
+        internal abstract ISetterInstance CreateSetterInstance(IStyleable target, object? value);
 
         /// <summary>
         /// Overrides the metadata for the property on the specified type.

src/Avalonia.Base/DirectPropertyBase.cs

@@ -1,6 +1,7 @@
 using System;
 using Avalonia.Data;
 using Avalonia.Reactive;
+using Avalonia.Styling;
 using Avalonia.Utilities;
 
 namespace Avalonia
@@ -120,12 +121,6 @@ public void OverrideMetadata(Type type, DirectPropertyMetadata<TValue> metadata)
             base.OverrideMetadata(type, metadata);
         }
 
-        /// <inheritdoc/>
-        public override void Accept<TData>(IAvaloniaPropertyVisitor<TData> visitor, ref TData data)
-        {
-            visitor.Visit(this, ref data);
-        }
-
         /// <inheritdoc/>
         internal override void RouteClearValue(AvaloniaObject o)
         {
@@ -181,5 +176,30 @@ internal override void RouteInheritanceParentChanged(AvaloniaObject o, AvaloniaO
         {
             throw new NotSupportedException("Direct properties do not support inheritance.");
         }
+
+        internal override ISetterInstance CreateSetterInstance(IStyleable target, object? value)
+        {
+            if (value is IBinding binding)
+            {
+                return new PropertySetterBindingInstance<TValue>(
+                    target,
+                    this,
+                    binding);
+            }
+            else if (value is ITemplate template && !typeof(ITemplate).IsAssignableFrom(PropertyType))
+            {
+                return new PropertySetterLazyInstance<TValue>(
+                    target,
+                    this,
+                    () => (TValue)template.Build());
+            }
+            else
+            {
+                return new PropertySetterInstance<TValue>(
+                    target,
+                    this,
+                    (TValue)value!);
+            }
+        }
     }
 }

src/Avalonia.Base/Interactivity/IInteractive.cs

@@ -28,37 +28,13 @@ void AddHandler(
             RoutingStrategies routes = RoutingStrategies.Direct | RoutingStrategies.Bubble,
             bool handledEventsToo = false);
 
-        /// <summary>
-        /// Adds a handler for the specified routed event.
-        /// </summary>
-        /// <typeparam name="TEventArgs">The type of the event's args.</typeparam>
-        /// <param name="routedEvent">The routed event.</param>
-        /// <param name="handler">The handler.</param>
-        /// <param name="routes">The routing strategies to listen to.</param>
-        /// <param name="handledEventsToo">Whether handled events should also be listened for.</param>
-        /// <returns>A disposable that terminates the event subscription.</returns>
-        void AddHandler<TEventArgs>(
-            RoutedEvent<TEventArgs> routedEvent,
-            EventHandler<TEventArgs> handler,
-            RoutingStrategies routes = RoutingStrategies.Direct | RoutingStrategies.Bubble,
-            bool handledEventsToo = false) where TEventArgs : RoutedEventArgs;
-
         /// <summary>
         /// Removes a handler for the specified routed event.
         /// </summary>
         /// <param name="routedEvent">The routed event.</param>
         /// <param name="handler">The handler.</param>
         void RemoveHandler(RoutedEvent routedEvent, Delegate handler);
 
-        /// <summary>
-        /// Removes a handler for the specified routed event.
-        /// </summary>
-        /// <typeparam name="TEventArgs">The type of the event's args.</typeparam>
-        /// <param name="routedEvent">The routed event.</param>
-        /// <param name="handler">The handler.</param>
-        void RemoveHandler<TEventArgs>(RoutedEvent<TEventArgs> routedEvent, EventHandler<TEventArgs> handler)
-            where TEventArgs : RoutedEventArgs;
-
         /// <summary>
         /// Adds the object's handlers for a routed event to an event route.
         /// </summary>

src/Avalonia.Base/StyledPropertyBase.cs

@@ -2,6 +2,7 @@
 using System.Diagnostics;
 using Avalonia.Data;
 using Avalonia.Reactive;
+using Avalonia.Styling;
 using Avalonia.Utilities;
 
 namespace Avalonia
@@ -158,12 +159,6 @@ public void OverrideMetadata(Type type, StyledPropertyMetadata<TValue> metadata)
             base.OverrideMetadata(type, metadata);
         }
 
-        /// <inheritdoc/>
-        public override void Accept<TData>(IAvaloniaPropertyVisitor<TData> visitor, ref TData data)
-        {
-            visitor.Visit(this, ref data);
-        }
-
         /// <summary>
         /// Gets the string representation of the property.
         /// </summary>
@@ -237,6 +232,31 @@ internal override void RouteInheritanceParentChanged(
             o.InheritanceParentChanged(this, oldParent);
         }
 
+        internal override ISetterInstance CreateSetterInstance(IStyleable target, object? value)
+        {
+            if (value is IBinding binding)
+            {
+                return new PropertySetterBindingInstance<TValue>(
+                    target,
+                    this,
+                    binding);
+            }
+            else if (value is ITemplate template && !typeof(ITemplate).IsAssignableFrom(PropertyType))
+            {
+                return new PropertySetterLazyInstance<TValue>(
+                    target,
+                    this,
+                    () => (TValue)template.Build());
+            }
+            else
+            {
+                return new PropertySetterInstance<TValue>(
+                    target,
+                    this,
+                    (TValue)value!);
+            }
+        }
+
         private object? GetDefaultBoxedValue(Type type)
         {
             _ = type ?? throw new ArgumentNullException(nameof(type));

src/Avalonia.Base/Styling/Setter.cs

@@ -16,7 +16,7 @@ namespace Avalonia.Styling
     /// A <see cref="Setter"/> is used to set a <see cref="AvaloniaProperty"/> value on a
     /// <see cref="AvaloniaObject"/> depending on a condition.
     /// </remarks>
-    public class Setter : ISetter, IAnimationSetter, IAvaloniaPropertyVisitor<Setter.SetterVisitorData>
+    public class Setter : ISetter, IAnimationSetter
     {
         private object? _value;
 
@@ -68,68 +68,7 @@ public ISetterInstance Instance(IStyleable target)
                 throw new InvalidOperationException("Setter.Property must be set.");
             }
 
-            var data = new SetterVisitorData
-            {
-                target = target,
-                value = Value,
-            };
-
-            Property.Accept(this, ref data);
-            return data.result!;
-        }
-
-        void IAvaloniaPropertyVisitor<SetterVisitorData>.Visit<T>(
-            StyledPropertyBase<T> property,
-            ref SetterVisitorData data)
-        {
-            if (data.value is IBinding binding)
-            {
-                data.result = new PropertySetterBindingInstance<T>(
-                    data.target,
-                    property,
-                    binding);
-            }
-            else if (data.value is ITemplate template && !typeof(ITemplate).IsAssignableFrom(property.PropertyType))
-            {
-                data.result = new PropertySetterLazyInstance<T>(
-                    data.target,
-                    property,
-                    () => (T)template.Build());
-            }
-            else
-            {
-                data.result = new PropertySetterInstance<T>(
-                    data.target,
-                    property,
-                    (T)data.value!);
-            }
-        }
-
-        void IAvaloniaPropertyVisitor<SetterVisitorData>.Visit<T>(
-            DirectPropertyBase<T> property,
-            ref SetterVisitorData data)
-        {
-            if (data.value is IBinding binding)
-            {
-                data.result = new PropertySetterBindingInstance<T>(
-                    data.target,
-                    property,
-                    binding);
-            }
-            else if (data.value is ITemplate template && !typeof(ITemplate).IsAssignableFrom(property.PropertyType))
-            {
-                data.result = new PropertySetterLazyInstance<T>(
-                    data.target,
-                    property,
-                    () => (T)template.Build());
-            }
-            else
-            {
-                data.result = new PropertySetterInstance<T>(
-                    data.target,
-                    property,
-                    (T)data.value!);
-            }
+            return Property.CreateSetterInstance(target, Value);
         }
 
         private struct SetterVisitorData

src/Avalonia.Base/Threading/IDispatcher.cs

@@ -26,15 +26,6 @@ public interface IDispatcher
         /// <param name="priority">The priority with which to invoke the method.</param>
         void Post(Action action, DispatcherPriority priority = default);
 
-        /// <summary>
-        /// Posts an action that will be invoked on the dispatcher thread.
-        /// </summary>
-        /// <typeparam name="T">type of argument</typeparam>
-        /// <param name="action">The method to call.</param>
-        /// <param name="arg">The argument of method to call.</param>
-        /// <param name="priority">The priority with which to invoke the method.</param>
-        void Post<T>(Action<T> action, T arg, DispatcherPriority priority = default);
-
         /// <summary>
         /// Invokes a action on the dispatcher thread.
         /// </summary>
@@ -43,14 +34,6 @@ public interface IDispatcher
         /// <returns>A task that can be used to track the method's execution.</returns>
         Task InvokeAsync(Action action, DispatcherPriority priority = default);
 
-        /// <summary>
-        /// Invokes a method on the dispatcher thread.
-        /// </summary>
-        /// <param name="function">The method.</param>
-        /// <param name="priority">The priority with which to invoke the method.</param>
-        /// <returns>A task that can be used to track the method's execution.</returns>
-        Task<TResult> InvokeAsync<TResult>(Func<TResult> function, DispatcherPriority priority = default);
-
         /// <summary>
         /// Queues the specified work to run on the dispatcher thread and returns a proxy for the
         /// task returned by <paramref name="function"/>.
@@ -59,14 +42,5 @@ public interface IDispatcher
         /// <param name="priority">The priority with which to invoke the method.</param>
         /// <returns>A task that represents a proxy for the task returned by <paramref name="function"/>.</returns>
         Task InvokeAsync(Func<Task> function, DispatcherPriority priority = default);
-
-        /// <summary>
-        /// Queues the specified work to run on the dispatcher thread and returns a proxy for the
-        /// task returned by <paramref name="function"/>.
-        /// </summary>
-        /// <param name="function">The work to execute asynchronously.</param>
-        /// <param name="priority">The priority with which to invoke the method.</param>
-        /// <returns>A task that represents a proxy for the task returned by <paramref name="function"/>.</returns>
-        Task<TResult> InvokeAsync<TResult>(Func<Task<TResult>> function, DispatcherPriority priority = default);
     }
 }

src/Avalonia.Controls/AutoCompleteBox.cs

@@ -1346,12 +1346,16 @@ protected override void OnApplyTemplate(TemplateAppliedEventArgs e)
         /// enabled.
         /// </summary>
         /// <param name="property">The property.</param>
-        /// <param name="value">The new binding value for the property.</param>
-        protected override void UpdateDataValidation<T>(AvaloniaProperty<T> property, BindingValue<T> value)
+        /// <param name="state">The current data binding state.</param>
+        /// <param name="error">The current data binding error, if any.</param>
+        protected override void UpdateDataValidation(
+            AvaloniaProperty property,
+            BindingValueType state,
+            Exception? error)
         {
             if (property == TextProperty || property == SelectedItemProperty)
             {
-                DataValidationErrors.SetError(this, value.Error);
+                DataValidationErrors.SetError(this, error);
             }
         }
 

src/Avalonia.Controls/Button.cs

@@ -498,12 +498,15 @@ protected override void OnPropertyChanged(AvaloniaPropertyChangedEventArgs chang
         protected override AutomationPeer OnCreateAutomationPeer() => new ButtonAutomationPeer(this);
 
         /// <inheritdoc/>
-        protected override void UpdateDataValidation<T>(AvaloniaProperty<T> property, BindingValue<T> value)
+        protected override void UpdateDataValidation(
+            AvaloniaProperty property,
+            BindingValueType state,
+            Exception? error)
         {
-            base.UpdateDataValidation(property, value);
+            base.UpdateDataValidation(property, state, error);
             if (property == CommandProperty)
             {
-                if (value.Type == BindingValueType.BindingError)
+                if (state == BindingValueType.BindingError)
                 {
                     if (_commandCanExecute)
                     {