ConditionalWeakTable<br>컴파일러가 대상 필드를 위탁 관리 대상에 동적으로 추가할 수 있도록 합니다.

using System;
using System.Runtime.CompilerServices;

public class Example
{
   public static void Main()
   {
      var mc1 = new ManagedClass();
      var mc2 = new ManagedClass();
      var mc3 = new ManagedClass();

      var cwt = new ConditionalWeakTable<ManagedClass, ClassData>();
      cwt.Add(mc1, new ClassData());          
      cwt.Add(mc2, new ClassData());
      cwt.Add(mc3, new ClassData());

      var wr2 = new WeakReference(mc2);
      mc2 = null;

      GC.Collect();

      ClassData data = null; 

      if (wr2.Target == null)
          Console.WriteLine("No strong reference to mc2 exists.");   
      else if (cwt.TryGetValue(mc2, out data))
          Console.WriteLine("Data created at {0}", data.CreationTime);      
      else
          Console.WriteLine("mc2 not found in the table.");
   }
}

public class ManagedClass
{ 
}

public class ClassData
{
   public DateTime CreationTime;
   public object Data;   

   public ClassData()
   {
      CreationTime = DateTime.Now;
      this.Data  = new object();     
   }
}
// The example displays the following output:
//       No strong reference to mc2 exists.

using System;
using System.Runtime.CompilerServices;
using System.Threading;

public class ManagedObject
{
}

public class AttachedProperty
{
   public AttachedProperty(ManagedObject obj, int ctr)
   {
      this.obj = obj;
      this.ctr = ctr;
   }

   public int ctr;
   public ManagedObject obj; 
}

public class Example
{
   public static void Main()
   {
      // Create two managed objects.
      ManagedObject m1 = new ManagedObject();
      ManagedObject m2 = new ManagedObject();

      // Define their attached property values.
      AttachedProperty p1 = new AttachedProperty(null, 0);
      AttachedProperty p2 = new AttachedProperty(m1, 1);

      // Create the table and add the key/value pairs.
      var table = new ConditionalWeakTable<ManagedObject, AttachedProperty>();
      table.Add(m1, p1);
      table.Add(m2, p2);

      // Destroy m1.
      m1 = null;
      // Sleep for 1 second to allow m1 to be garbage collected.
      Thread.Sleep(1000);
      // Reinstantiate m1
      m1 = new ManagedObject();

      // Try to retrieve m1 and m2.
      AttachedProperty value = null;   
      if (table.TryGetValue(m2, out value))
         Console.WriteLine("m2: ({0}, {1})", value.obj, value.ctr);
      else
         Console.WriteLine("m2 is not in the table.");

      if (table.TryGetValue(m1, out value))
         Console.WriteLine("m1: ({0}, {1})", value.obj, value.ctr);
      else
         Console.WriteLine("m1 is not in the table.");
   }
}
// The example displays the following output:
//       m2: (ManagedObject, 1)
//       m1 is not in the table.