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//
// System.WeakReference.cs
//
// Author:
// Ajay kumar Dwivedi (adwiv@yahoo.com)
//
using System.Runtime.Serialization;
using System.Runtime.InteropServices;
namespace System
{
/// <summary>
/// Summary description for WeakReference.
/// </summary>
[Serializable]
public class WeakReference : ISerializable
{
//Fields
private bool isLongReference;
private GCHandle gcHandle;
// Helper method for constructors
//Should not be called from any other method.
private void AllocateHandle(Object target)
{
if(this.isLongReference)
{
this.gcHandle = GCHandle.Alloc(target, GCHandleType.WeakTrackResurrection);
}
else
{
this.gcHandle = GCHandle.Alloc(target, GCHandleType.Weak);
}
}
//Constructors
public WeakReference(object target)
: this(target,false)
{}
public WeakReference(object target, bool trackResurrection)
{
this.isLongReference = trackResurrection;
AllocateHandle(target);
}
protected WeakReference(SerializationInfo info, StreamingContext context)
{
if (info == null)
throw new ArgumentNullException ("info");
this.isLongReference = info.GetBoolean ("TrackResurrection");
Object target = info.GetValue ("TrackedObject", typeof (System.Object));
AllocateHandle(target);
}
// Properties
public virtual bool IsAlive
{
get
{
//Target property takes care of the exception
return (Target != null);
}
}
public virtual object Target
{
get
{
//Exception is thrown by gcHandle's Target
return this.gcHandle.Target;
}
set
{
this.gcHandle.Target = value;
}
}
public virtual bool TrackResurrection
{
get
{
return this.isLongReference;
}
}
//Methods
~WeakReference()
{
gcHandle.Free();
}
public virtual void GetObjectData(SerializationInfo info, StreamingContext context)
{
if (info == null)
throw new ArgumentNullException ("info");
info.AddValue ("TrackResurrection", TrackResurrection);
try {
info.AddValue ("TrackedObject", Target);
} catch(Exception) {
info.AddValue("TrackedObject",null);
}
}
}
}
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