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WPF Control Factory

, 20 Apr 2010
This article explains some advantages and disadvantages of factories, and shows one to use for generating WPF Controls.
WpfControlsAndSample.zip
WpfControlsAndSample
Pfz.ClassLibraries
Pfz
Caching
Collections
DataTypes
Extensions
Pfz.snk
Properties
Ranges
Threading
Pfz.WpfControls
BoundGridParts
Extensions
Pfz.WpfControls.snk
Properties
TypeConverters
WpfControlFactorySample
bin
Debug
Pfz.dll
Pfz.WpfControls.dll
WpfControlFactorySample.exe
Properties
Settings.settings
WpfControlFactorySample.suo
using System;
using Pfz.Extensions.DisposeExtensions;
using Pfz.Extensions.MonitorLockExtensions;

namespace Pfz.Threading
{
	/// <summary>
	/// This class is useful if you need to implement the dispose pattern
	/// in a thread-safe manner.
	/// It guarantees that dispose will be called only once, even if many 
	/// threads try to call Dispose at once. In your code, you must lock 
	/// DisposeLock, check if the object is disposed and call anything that 
	/// must be guaranteed to run before dispose inside the lock block.
	/// </summary>
	public abstract class ThreadSafeDisposable:
		IAdvancedDisposable
	{
		#region Destructor
			/// <summary>
			/// Calls Dispose(false);
			/// </summary>
			~ThreadSafeDisposable()
			{
				Dispose(false);
			}
		#endregion
		#region Dispose
			#region Without parameters
				/// <summary>
				/// Calls Dispose(true) to release all resources.
				/// Guarantees that only a single call to Dispose(true) is done 
				/// even if  this method is invoked multiple times or by many 
				/// different threads at the same time.
				/// </summary>
				public void Dispose()
				{
					IDisposable disposer = null;
					try
					{
						AbortSafe.Run(() => disposer = fDisposeLock.LockWithTimeout());

						if (fWasDisposed)
							return;
						
						try
						{
						}
						finally
						{
							fWasDisposed = true;
							
							disposer.Dispose();
							
							Dispose(true);
							GC.SuppressFinalize(this);
						}
					}
					finally
					{
						disposer.CheckedDispose();
					}
				}
			#endregion
			#region Protected - bool disposing
				/// <summary>
				/// Implement this method to release all resources used by this object.
				/// </summary>
				/// <param name="disposing">
				/// This parameter is true if it was called by a user call to Dispose(),
				/// and false if it was called by a destructor. If false, you don't need
				/// to release managed resources (in general, you don't need to set any
				/// variables to null or even reference other objects, only freeing 
				/// "unsafe" pointers).
				/// </param>
				protected virtual void Dispose(bool disposing)
				{
				}
			#endregion
		#endregion
		
		#region Properties
			#region WasDisposed
				private volatile bool fWasDisposed;
				
				/// <summary>
				/// Returns true if a call to Dispose was already done (or still in
				/// progress in another thread). If it is true, you can't continue
				/// to use your object.
				/// </summary>
				public bool WasDisposed
				{
					get
					{
						return fWasDisposed;
					}
				}
			#endregion
			#region DisposeLock
				private volatile object fDisposeLock = new object();
				
				/// <summary>
				/// This is the lock used during dispose. You may want to lock
				/// some of your code against dispose using this lock.
				/// The preferred way to use it is: AbortSafe.Lock
				/// (
				///		DisposeLock,
				///		delegate
				///		{
				///			CheckUndisposed();
				///		
				///			... your protected code here ...
				///		}
				///	);
				/// </summary>
				public object DisposeLock
				{
					get
					{
						return fDisposeLock;
					}
				}
			#endregion
		#endregion
		#region Methods
			#region CheckUndisposed
				/// <summary>
				/// Checks if the objects is disposed. If it is, throws an 
				/// ObjectDisposedException. Call this as the first method inside a 
				/// AbortSafe.Lock
				/// (
				///		DisposeLock,
				///		delegate
				///		{
				///			CheckUndisposed(); 
				///			... your protected code here ...
				///		}
				///	);
				/// 
				/// or simple call it without any lock if you only want to throw
				/// an exception if the object is already disposed but such a call
				/// is read-only.
				/// </summary>
				public void CheckUndisposed()
				{
					if (fWasDisposed)
						throw new ObjectDisposedException(GetType().FullName);
				}
			#endregion
		#endregion
	}
}

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About the Author

Paulo Zemek
Architect
Canada Canada
I started to program computers when I was 11 years old, as a hobbist, 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 they 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
Microsoft MVP 2013

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