Loaded="{foo:MethodBinding BarMethod}" みたいにできるやつの作りかけ

MethodBinding.cs

using System;
using System.Collections.Generic;
using System.Reflection;
using System.Windows;
using System.Windows.Markup;

namespace Test
{
	[MarkupExtensionReturnType(typeof(Delegate))]
	class MethodBinding : MarkupExtension
	{
		public string Path { get; }

		public MethodCommand(string path) =>
			Path = path;

		public override object ProvideValue(IServiceProvider serviceProvider)
		{
			var targetInfo = (IProvideValueTarget)serviceProvider.GetService(typeof(IProvideValueTarget));

			if (!(targetInfo.TargetProperty is EventInfo ei))
				throw new NotSupportedException("MethodBinding must be bound to an event.");

			var targetObject = (FrameworkElement)targetInfo.TargetObject;
			EventHandler handler = (object sender, EventArgs e) =>
			{
				var dataContext = targetObject.DataContext;
				
				// TODO: ここで Path で指定されたメソッドを呼び出したいけど . 区切りで階層辿るとか引数与えたいとか考えだしたら面倒になった
			};

			return Delegate.CreateDelegate(ei.EventHandlerType, handler.Target, handler.Method);
		}
	}
}