Implementing a generic WeakReference<T> in C#
Check out the replacement EquatableWeakReference
A weak reference lets you hold a reference to an object that will not prevent it from being garbage collected. There are a few scenarios where this might be important – such as listening for events, caching, various MVC patterns.
.NET and Java supports weak references with the aptly named WeakReference class. In .NET it exposes a .Target property of type object that weakly points to whatever you like.
Java also sports a generic WeakReference
Here is my attempt at a WeakReference
using System;
using System.Runtime.InteropServices;
public class WeakReference<T> : IDisposable {
private GCHandle handle;
private bool trackResurrection;
public WeakReference(T target)
: this(target, false) {
}
public WeakReference(T target, bool trackResurrection) {
this.trackResurrection = trackResurrection;
this.Target = target;
}
~WeakReference() {
Dispose();
}
public void Dispose() {
handle.Free();
GC.SuppressFinalize(this);
}
public virtual bool IsAlive {
get { return (handle.Target != null); }
}
public virtual bool TrackResurrection {
get { return this.trackResurrection; }
}
public virtual T Target {
get {
object o = handle.Target;
if ((o == null) || (!(o is T)))
return default(T);
else
return (T)o;
}
set {
handle = GCHandle.Alloc(value,
this.trackResurrection ? GCHandleType.WeakTrackResurrection : GCHandleType.Weak);
}
}
}
I’ve allowed Target to be settable against my better judgment to bring it more in like with WeakReference. It’s still not serializable though unlike WeakReference.
[)amien
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