Implementing Factory Method Pattern

Many times we come across a situation where we want to have a some way to create instance of related classes. Using Factory Method pattern we can achieve this.

Main Parts of this pattern are,

1. Product(Interface - IController)
2. Concrete Product(MainController, LoginController etc.. implementing IController i.e. Product)
3. Creator(IControllerCreatorHelper)
4. ConcreteCreator(CControllerInstanceCreator)

While Implementing MVC pattern for one of my project, i came across a situation where i required generalized mechanism to create a singleton instance of a every Controller class.

For this i started creating a hierarchy for Controller classes where every Controller class has to implement IController interface.

public interface IMainController:IController

{

___________

___________

}

public class MainController: IMainController
{

public static IMainController Instance
{
get
{

return(IMainController)CControllerInstanceCreator<MainController>.Instance;

}
}

}

internal class CControllerCreatorHelper:IControllerCreatorHelper
{

#region IControllerCreatorHelper Members

public IMainController CreateMainControllerInstance()
{
return MainController.Instance;
}

#endregion

}

public class CControllerInstanceCreator where T : IController, new()
{
private static T m_oController;
private static object syncRoot = new Object();

public static IController Instance
{
get
{
if (m_oController == null)
{
lock (syncRoot)
{
m_oController = new T();
}
}
return m_oController;
}

}
}

By reading the code you can observe CControllerCreatorHelper class contains a method for every controller to return the singleton instance. CControllerInstanceCreator class actully returns a singleton instance of any type implementing IController interface.

For more information on Factory method pattern plz. visit

http://www.dofactory.com/Patterns/PatternFactory.aspx