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C# Design Patterns: the Singleton pattern

January 13, 2009

Summary

A class that only allows one instance of itself, which is accessed via a static property.

Example usage

The commonest example is an application only allowing one instance of itself, much like Windows Media Player does. Another example is a ‘global’ instance of a class, which contains settings or config information.

This is Jon Skeet’s lazy implementation example. He has a full discussion on the various ways of implementing a singleton in C#, the example below being the final version. The full article can be found here

public sealed class Singleton
{
Singleton()
{
}
public static Singleton Instance
{
get
{
return Nested.instance;
}
}
class Nested
{
// Explicit static constructor to tell C# compiler
// not to mark type as beforefieldinit
static Nested()
{
}
internal static readonly Singleton instance = new Singleton();
}
}
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Chris Small

I'm Chris Small, a software engineer working in London. This is my tech blog. Find out more about me via GithubStackoverflowResume