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using System;
using System.Runtime.Serialization;
namespace Pfz.Caching
{
/// <summary>
/// This is a WeakReference class with KeepAlive capability.
/// Everytime you get the Target from this WeakReference, it calls the GCUtils.KeepAlive.
/// This is a very simple way to use weak-references only to your objects and also
/// keep them alive if they are used frequently.
/// </summary>
[Serializable]
public class KeepAliveWeakReference:
WeakReference
{
#region Constructors
/// <summary>
/// Constructs a KeepAliveWeakReference pointing to a target.
/// </summary>
/// <param name="target">The target of this KeepAliveWeakReference.</param>
public KeepAliveWeakReference(object target):
base(target)
{
GCUtils.KeepAlive(target);
}
/// <summary>
/// Constructs a KeepAliveWeakReference pointing to a target and allowing to trackResurrection.
/// The Caching framework does not use this constructor, it is only here to keep the functionality
/// of the second parameter present in the System.WeakReference constructor.
/// </summary>
/// <param name="target">The target of this WeakReference.</param>
/// <param name="trackResurrection">Boolean indicating if this WeakReference must trackResurrection.</param>
public KeepAliveWeakReference(object target, bool trackResurrection):
base(target, trackResurrection)
{
GCUtils.KeepAlive(target);
}
/// <summary>
/// Constructs a KeepAliveWeakReference pointing to a target, allowing to trackResurrection and
/// allowing you to tell if immediateExpiration is allowed. The other two constructors always
/// do a KeepAlive, so they don't allow immediateExpiration.
/// </summary>
/// <param name="target">The target of this WeakReference.</param>
/// <param name="trackResurrection">Boolean indicating if this WeakReference must trackResurrection.</param>
/// <param name="allowImmediateExpiration">
/// If true, the target can be collected in the next collection.
/// If false, it will be kept alive at the next collection.
/// </param>
public KeepAliveWeakReference(object target, bool trackResurrection, bool allowImmediateExpiration):
base(target, trackResurrection)
{
if (!allowImmediateExpiration)
GCUtils.KeepAlive(target);
}
/// <summary>
/// Simple keeping the serialization constructor present in WeakReference.
/// </summary>
/// <param name="info"></param>
/// <param name="context"></param>
protected KeepAliveWeakReference(SerializationInfo info, StreamingContext context):
base(info, context)
{
}
#endregion
#region Target
/// <summary>
/// Overrides the WeakReference.Target, so it calls KeepAlive while gets or sets the Target.
/// </summary>
public override object Target
{
get
{
object result = base.Target;
GCUtils.KeepAlive(result);
return result;
}
set
{
GCUtils.Expire(base.Target);
base.Target = value;
GCUtils.KeepAlive(value);
}
}
#endregion
#region TargetAllowingExpiration
/// <summary>
/// This is equivalent to a custom WeakReference target, as it's gets or sets the target
/// without calling KeepAlive. Keep in mind that when an external code uses WeakReference,
/// you can pass a KeepAliveWeakReference as a parameter, and the conventional Target that
/// is used by default will have the KeepAlive effect.
/// </summary>
public object TargetAllowingExpiration
{
get
{
return base.Target;
}
set
{
base.Target = value;
}
}
#endregion
}
/// <summary>
/// A typed version of weak-reference.
/// Note that it simple hides the untyped Target and TargetAllowingExpiration.
/// If you cast this object as a simple WeakReference you can still set
/// an invalid typed target to it. This is only a helper class to avoid
/// manual casts.
/// </summary>
/// <typeparam name="T">The type of the objects used by this weak-reference.</typeparam>
[Serializable]
public sealed class KeepAliveWeakReference<T>:
KeepAliveWeakReference
where
T: class
{
#region Constructors
/// <summary>
/// Constructs a KeepAliveWeakReference pointing to a target.
/// </summary>
/// <param name="target">The target of this KeepAliveWeakReference.</param>
public KeepAliveWeakReference(object target):
base(target)
{
}
/// <summary>
/// Constructs a KeepAliveWeakReference pointing to a target and allowing to trackResurrection.
/// The Caching framework does not use this constructor, it is only here to keep the functionality
/// of the second parameter present in the System.WeakReference constructor.
/// </summary>
/// <param name="target">The target of this WeakReference.</param>
/// <param name="trackResurrection">Boolean indicating if this WeakReference must trackResurrection.</param>
public KeepAliveWeakReference(object target, bool trackResurrection):
base(target, trackResurrection)
{
}
/// <summary>
/// Constructs a KeepAliveWeakReference pointing to a target, allowing to trackResurrection and
/// allowing you to tell if immediateExpiration is allowed. The other two constructors always
/// do a KeepAlive, so they don't allow immediateExpiration.
/// </summary>
/// <param name="target">The target of this WeakReference.</param>
/// <param name="trackResurrection">Boolean indicating if this WeakReference must trackResurrection.</param>
/// <param name="allowImmediateExpiration">
/// If true, the target can be collected in the next collection.
/// If false, it will be kept alive at the next collection.
/// </param>
public KeepAliveWeakReference(object target, bool trackResurrection, bool allowImmediateExpiration):
base(target, trackResurrection, allowImmediateExpiration)
{
}
/// <summary>
/// Simple keeping the serialization constructor present in WeakReference.
/// </summary>
/// <param name="info"></param>
/// <param name="context"></param>
private KeepAliveWeakReference(SerializationInfo info, StreamingContext context):
base(info, context)
{
}
#endregion
#region Target
/// <summary>
/// Gets or sets the typed target, calling GCUtils.KeepAlive()
/// while doing it.
/// </summary>
public new T Target
{
get
{
return base.Target as T;
}
set
{
base.Target = value;
}
}
#endregion
#region TargetAllowingExpiration
/// <summary>
/// Gets or sets the typed-target, without calling GCUtils.KeepAlive().
/// </summary>
public new T TargetAllowingExpiration
{
get
{
return base.TargetAllowingExpiration as T;
}
set
{
base.TargetAllowingExpiration = value;
}
}
#endregion
}
}
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I started to program computers when I was 11 years old, as a hobbyist, programming in AMOS Basic and Blitz Basic for Amiga.
At 12 I had my first try with assembler, but it was too difficult at the time. Then, in the same year, I learned C and, after learning C, I was finally able to learn assembler (for Motorola 680x0).
Not sure, but probably between 12 and 13, I started to learn C++. I always programmed "in an object oriented way", but using function pointers instead of virtual methods.
At 15 I started to learn Pascal at school and to use Delphi. At 16 I started my first internship (using Delphi). At 18 I started to work professionally using C++ and since then I've developed my programming skills as a professional developer in C++ and C#, generally creating libraries that help other developers do their work easier, faster and with less errors.
Want more info or simply want to contact me?
Take a look at:
http://paulozemek.azurewebsites.net/
Or e-mail me at: paulozemek@outlook.com
Codeproject MVP 2012, 2015 & 2016
Microsoft MVP 2013-2014 (in October 2014 I started working at Microsoft, so I can't be a Microsoft MVP anymore).