Singletone.

Let's start from simpliest things.

The main idea of Singletone pattern is: private class constructor, private field with the only instance of class and public method that returns this instance.


We can implement it this way (there are variations, but as I can see this is the most popular way):

class SingletoneExample
{
 private static SingletoneExample instance = null;

 private SingletoneExample()
 {
 }

 public static SingletoneExample getInstance
 {
  public get
  {
   if (instance == null)
   {
    instance = new SingletoneExample();
   }
   return instance;
  }
  private set;
 }
}

To test this pattern you can use next code:

using System;
namespace Singletone
{
 class Program
 {
  static void Main(string[] args)
  {
   SingletoneExample singl = SingletoneExample.getInstance;
   singl.Prop = "op";
   Console.WriteLine(singl.Prop);
   SingletoneExample singl1 = SingletoneExample.getInstance;
   Console.WriteLine(singl1.Prop);
   Console.ReadLine();
  }
 }

 class SingletoneExample
 {
  private static SingletoneExample instance = null;
  private string prop;
  
  private SingletoneExample()
  {
  }

  public static SingletoneExample getInstance
  {
   public get
   {
    if (instance == null)
    {
     instance = new SingletoneExample();
    }
    return instance;
   }
   private set;
  }

  public string Prop
  {
   public get
   {
    return prop;
   }
   public set
   {
    prop = value;
   }
  }
 }
}