Command Design Pattern in C#

Encapsulates a request as an object, thereby letting you parameterize clients with different requests, queue or log requests, and support undoable operations.

This structural code demonstrates the Command pattern which stores requests as objects allowing clients to execute or playback the requests.

using System;

  class MainApp
  {
    static void Main()
    {
      // Create receiver, command, and invoker 
      Receiver receiver = new Receiver();
      Command command = new ConcreteCommand(receiver);
      Invoker invoker = new Invoker();

      // Set and execute command 
      invoker.SetCommand(command);
      invoker.ExecuteCommand();

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

  // "Command" 
  abstract class Command 
  {
    protected Receiver receiver;

    // Constructor 
    public Command(Receiver receiver)
    {
      this.receiver = receiver;
    }

    public abstract void Execute();
  }

  // "ConcreteCommand" 
  class ConcreteCommand : Command
  {
    // Constructor 
    public ConcreteCommand(Receiver receiver) : 
      base(receiver) 
    {  
    }

    public override void Execute()
    {
      receiver.Action();
    }
  }

  // "Receiver" 
  class Receiver 
  {
    public void Action()
    {
      Console.WriteLine("Called Receiver.Action()");
    }
  }

  // "Invoker" 
  class Invoker 
  {
    private Command command;

    public void SetCommand(Command command)
    {
      this.command = command;
    }

    public void ExecuteCommand()
    {
      command.Execute();
    }    
  }