Generic singleton pattern in C#

The singleton pattern is simple enough to understand but you end up writing the same boiler plate code each time. Time to extract it into a generic class, write once use many times :)

So here is the classic singleton pattern in C#.

public class MySingleton
{
    private static MySingleton _instance = null;

    MySingleton() {}

    public static MySingleton Instance
    {
        get
        {
            if (_instance == null)
            {
                _instance = new Singleton();
            }

            return _instance;
        }
    }
    
    // other stuff here
}

Simple enough but has to be re-implemented each time.

Enter generics to the rescue :)

public static class Singleton<T>
    where T : new, class
{
    private static T _instance = null;

    public static T Instance
    {
        get
        {
            if (_instance == null)
            {
                _instance = new T();
            }

            return _instance;
        }
    }
}

And to use it...

public class Thing() {}
public class AnotherThing() {}

var singletonThing1 = Singleton<Thing>.Instance;
var singletonThing2 = Singleton<AnotherThing>.Instance;

So what is going on here. When you stack generics on statics you end up with a separate static instance for each generic type you use.

Feel free to ask any questions :)

Happy coding

Woz