Strategy Pattern

The strategy pattern is useful for situations where it is necessary to dynamically swap the algorithms used in an application. The strategy pattern is intended to provide a means to define a family of algorithms, encapsulate each one as an object, and make them interchangeable. The strategy pattern lets the algorithms vary independently from clients that use them.

EXAMPLE

Sample Code in C#;
Strategy - Interface: The classes that implement a concrete strategy should implement it. The context class uses this to call the concrete strategy.
ConcreteStrategy: Implements the algorithm using the strategy interface.
Context: configured with a ConcreteStrategy object and maintains a reference to a Strategy object



using System;



namespace Wikipedia.Patterns.Strategy

{

  

	// MainApp test application

	class MainApp

	{

		static void Main()

		{

			Context context;

      

			// Three contexts following different strategies

			context = new Context(new ConcreteStrategyA());

			context.Execute();



			context = new Context(new ConcreteStrategyB());

			context.Execute();



			context = new Context(new ConcreteStrategyC());

			context.Execute();

     

			Console.Read();

		}

	}



	// "Strategy"

	interface  Strategy

	{

		void Execute();

	}



	// "ConcreteStrategyA"

	class ConcreteStrategyA : Strategy

	{

		public void Execute()

		{

			Console.WriteLine(

				"Called ConcreteStrategyA.Execute()");

		}

	}



	// "ConcreteStrategyB"

	class ConcreteStrategyB : Strategy

	{

		public void Execute()

		{

			Console.WriteLine(

				"Called ConcreteStrategyB.Execute()");

		}

	}



	// "ConcreteStrategyC"

	class ConcreteStrategyC : Strategy

	{

		public void Execute()

		{

			Console.WriteLine(

				"Called ConcreteStrategyC.Execute()");

		}

	}



	// "Context"

	class Context

	{

		Strategy strategy;



		// Constructor

		public Context(Strategy strategy)

		{

			this.strategy = strategy;

		}



		public void Execute()

		{

			strategy.Execute();

		}

	}

}

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Information About

Strategy Pattern