While researching the facade pattern that can be implemented in similar way to HttpContext (in ASP.net), I came to a MSDN article that talks about implementing the singleton pattern in C#. It is fairly straight forward and works extremely well for what I needed for the project.
Here is the context class, which exposees the CMSManager (a factory class). The context manages the instantiation and destruction of the facade:
public sealed partial class CMSContext
{
/// <summary>
/// clutch object is used to prevent multiple access during the initialization
/// </summary>
private static object clutch = new object();
/// <summary>
/// actual instance of the CMSContext object
/// </summary>
private static volatile CMSContext uniqueInstance;
/// <summary>
/// instance of the CMSManager
/// </summary>
private CMSManager _cmsFacade = null;
/// <summary>
/// Gets the CMS facade.
/// </summary>
public CMSManager CMSFacade
{
get
{
return _cmsFacade;
}
}
/// <summary>
/// Prevents a default instance of the <see cref="CMSContext"/> class from being created.
/// </summary>
private CMSContext()
{
_cmsFacade = new CMSManager();
}
/// <summary>
/// Gets the instance.
/// </summary>
public static CMSContext Instance
{
get
{
if (uniqueInstance == null)
{
lock (clutch)
{
if (uniqueInstance == null)
uniqueInstance = new CMSContext();
}
}
return uniqueInstance;
}
}
/// <summary>
/// Releases unmanaged resources and performs other cleanup operations before the
/// <see cref="CMSContext"/> is reclaimed by garbage collection.
/// </summary>
~CMSContext()
{
if (_cmsFacade != null) _cmsFacade.Dispose();
}
}
This context class simplifies the way my client application accesses the CMS subsystem. It only requires two lines of code to access the factory class.
CMSContext cms = CMSContext.Instance; ContentFile f = new ContentFile(); f.FileName = "Test.txt"; f.FileSize = 10; f.LastModified = DateTime.Now; cms.CMSFacade.SaveContent(f);
One important note to achieve this simplicity, both context class and factory class should be autonomous; if there is any external dependency, it can make the client code messy.
