Strategy

// Strategy pattern -- Real World example

using System;
using System.Collections;

namespace DoFactory.GangOfFour.Strategy.RealWorld
{
  
  // MainApp test application

  class MainApp
  {
    static void Main()
    {
      // Two contexts following different strategies
      SortedList studentRecords = new SortedList();

      studentRecords.Add("Samual");
      studentRecords.Add("Jimmy");
      studentRecords.Add("Sandra");
      studentRecords.Add("Vivek");
      studentRecords.Add("Anna");

      studentRecords.SetSortStrategy(new QuickSort());
      studentRecords.Sort();

      studentRecords.SetSortStrategy(new ShellSort());
      studentRecords.Sort();

      studentRecords.SetSortStrategy(new MergeSort());
      studentRecords.Sort();

      // Wait for user
      Console.Read();
    }
  }

  // "Strategy"

  abstract class SortStrategy
  {
    public abstract void Sort(ArrayList list);
  }

  // "ConcreteStrategy"

  class QuickSort : SortStrategy
  {
    public override void Sort(ArrayList list)
    {
      list.Sort(); // Default is Quicksort
      Console.WriteLine("QuickSorted list ");
    }
  }

  // "ConcreteStrategy"

  class ShellSort : SortStrategy
  {
    public override void Sort(ArrayList list)
    {
      //list.ShellSort(); not-implemented
      Console.WriteLine("ShellSorted list ");
    }
  }

  // "ConcreteStrategy"

  class MergeSort : SortStrategy
  {
    public override void Sort(ArrayList list)
    {
      //list.MergeSort(); not-implemented
      Console.WriteLine("MergeSorted list ");
    }
  }

  // "Context"

  class SortedList
  {
    private ArrayList list = new ArrayList();
    private SortStrategy sortstrategy;

    public void SetSortStrategy(SortStrategy sortstrategy)
    {
      this.sortstrategy = sortstrategy;
    }

    public void Add(string name)
    {
      list.Add(name);
    }

    public void Sort()
    {
      sortstrategy.Sort(list);

      // Display results
      foreach (string name in list)
      {
        Console.WriteLine(" " + name);
      }
      Console.WriteLine();
    }
  }
}