gistfile1.cs

using System;
using System.Collections.Generic;
using System.ComponentModel;
using PostSharp.Aspects;
using PostSharp.Aspects.Advices;
using PostSharp.CodeModel;
using PostSharp.Extensibility;

namespace VanAOP.PostSharp._4to
{
	[Serializable]
	[IntroduceInterface(typeof (IEditableObject), OverrideAction = InterfaceOverrideAction.Ignore)]
	[MulticastAttributeUsage(MulticastTargets.Class, Inheritance = MulticastInheritance.Strict)]
	public sealed class EditableAttribute : InstanceLevelAspect, IEditableObject
	{
		private IDictionary<string, LocationInterceptionArgs> tempValues;
		private bool isInEditMode;

		[IntroduceMember(Visibility = Visibility.Family, IsVirtual = true, OverrideAction = MemberOverrideAction.Ignore)]
		public void BeginEdit()
		{
			isInEditMode = true;
			tempValues = new Dictionary<string, LocationInterceptionArgs>();
		}

		[IntroduceMember(Visibility = Visibility.Family, IsVirtual = true, OverrideAction = MemberOverrideAction.Ignore)]
		public void EndEdit()
		{
			isInEditMode = false;
			AplicarCambios();
		}

		[IntroduceMember(Visibility = Visibility.Family, IsVirtual = true, OverrideAction = MemberOverrideAction.Ignore)]
		public void CancelEdit()
		{
			isInEditMode = false;
		}

		private void AplicarCambios()
		{
			foreach (var kv in tempValues)
			{
				kv.Value.ProceedSetValue();
			}
		}

		[OnLocationSetValueAdvice, MulticastPointcut(Targets = MulticastTargets.Field)]
		public void OnFieldSet(LocationInterceptionArgs args)
		{
			if(!isInEditMode)
			{
				args.ProceedSetValue();
				return;
			}
			tempValues[args.Location.Name] = args;
		}

		[OnLocationGetValueAdvice, MulticastPointcut(Targets = MulticastTargets.Field)]
		public void OnFieldGet(LocationInterceptionArgs args)
		{
			LocationInterceptionArgs  result;
			if (!isInEditMode || !tempValues.TryGetValue(args.Location.Name, out result))
			{
				args.ProceedGetValue();
				return;
			}

			args.Value = result.Value;
		}		
	}

	[Editable]
	public class CajaAhorro
	{
		public virtual string Codigo { get; set; }
		public virtual string Titular { get; set; }
		public virtual double Saldo { get; private set; }
		
		public virtual void Acreditar(double importe)
		{
			Saldo += importe;
		}

		public virtual void Debitar(double importe)
		{
			Saldo -= importe;	
		}

	}

	[TestFixture]
	public class Test
	{
		//private T CrearProxy<T>(params object[] arguments)
		//{
		//    var proxyGenerator = new ProxyGenerator();
		//    return (T)proxyGenerator.CreateClassProxy(typeof(T),
		//        new[] { typeof(IEditableObject) },
		//        new IInterceptor[] { new EditableInterceptor() });
		//}

		[Test]
		public void puedo_editar_y_confirmar()
		{
			var caja = new CajaAhorro();

			caja.Titular = "Pedro";

			((IEditableObject)caja).BeginEdit();
			caja.Titular = "José";
			caja.Titular.Should().Be.EqualTo("José");
			((IEditableObject)caja).EndEdit();

			caja.Titular.Should().Be.EqualTo("José");
		}


		[Test]
		public void puedo_editar_y_cancelar()
		{
			var caja = new CajaAhorro();

			caja.Titular = "Pedro";

			((IEditableObject)caja).BeginEdit();
			caja.Titular = "José";
			((IEditableObject)caja).CancelEdit();

			caja.Titular.Should().Be.EqualTo("Pedro");
		}

		[Test]
		public void multiples_aspectos()
		{
			//var proxyGenerator = new ProxyGenerator();
			//var cuenta = (CajaAhorro)proxyGenerator.CreateClassProxy(typeof(CajaAhorro),
			//    new[] { typeof(IEditableObject) },
			//    new IInterceptor[] { // ¿ ? // });


			//cuenta.Titular = "Pedro";

			//((IEditableObject)cuenta).BeginEdit();
			//cuenta.Titular = "José";
			//((IEditableObject)cuenta).CancelEdit();
		}

		[Test]
		public void puedo_debitar_y_cancelar()
		{
			var caja = new CajaAhorro();

			caja.Titular = "Pedro";

			((IEditableObject)caja).BeginEdit();
			caja.Acreditar(221);
			((IEditableObject)caja).CancelEdit();

			caja.Saldo.Should().Be.EqualTo(0);
		}
	}
}