Singleton Design Pattern - Revision history

Admin: /* Example */

2019-12-10T18:29:33Z

Example

Admin: /* Output */

2019-12-10T18:28:40Z

Output

Admin at 18:24, 10 December 2019

2019-12-10T18:24:53Z

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Admin at 17:49, 9 December 2019

2019-12-09T17:49:56Z

Admin: Created page with "The singleton pattern is a software design pattern that restricts the instantiation of a class to one single instance. This is useful when exactly one object is needed to coor..."

2019-10-13T13:02:06Z

Created page with "The singleton pattern is a software design pattern that restricts the instantiation of a class to one single instance. This is useful when exactly one object is needed to coor..."

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The singleton pattern is a software design pattern that restricts the instantiation of a class to one single instance. This is useful when exactly one object is needed to coordinate actions across the system.

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 ==== Problem 2 ====
 ===== Example =====
 ===== Output =====

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 ===== Output =====
 === Second version - simple thread-safety and sealed ===
      class Program

← Older revision		Revision as of 17:49, 9 December 2019
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	The singleton pattern is a software design pattern that restricts the instantiation of a class to one single instance. This is useful when exactly one object is needed to coordinate actions across the system.		The singleton pattern is a software design pattern that restricts the instantiation of a class to one single instance. This is useful when exactly one object is needed to coordinate actions across the system.
		+	[[File:Singleton.png\|thumb\|Singleton]]
		+	== Problem ==
		+	Application needs one, and only one, instance of an object.
		+	==== Example ====
		+	Let’s take a look at an example, which is creating multiple objects.
		+
		+	class Program
		+	{
		+	static void Main(string[] args)
		+	{
		+	SingleTon obj1 = new SingleTon();
		+	SingleTon obj2 = new SingleTon();
		+	Console.WriteLine("Main End");
		+	Console.ReadLine();
		+	}
		+	}
		+	class SingleTon
		+	{
		+	private static int objectCounter = 0;
		+	public SingleTon()
		+	{
		+	objectCounter++;
		+	Console.WriteLine("objectCounter : " + objectCounter.ToString());
		+	}
		+	public void printText(string strData)
		+	{
		+	Console.WriteLine(strData);
		+	}
		+	}
		+	==== Output ====
		+	objectCounter : 1
		+	objectCounter : 2
		+	Main End
		+	== Solution ==
		+	The common characteristics of a Singleton Pattern:
		+	* A single constructor, that is private and parameter-less.
		+	* The class is sealed.
		+	* A static variable that holds a reference to the single created instance, if any.
		+	* A public static means of getting the reference to the single created instance, creating one if necessary.
		+	=== First version - not thread-safe ===
		+	==== Output ====
		+	=== Second version - simple thread-safety ===
		+	==== Output ====
		+	=== Third version - attempted thread-safety using double-check locking ===
		+	==== Output ====
		+	== Singleton class vs. Static class ==