// Singleton pattern in C# (see DESIGN PATTERNS)

// a class that manages a sole instance of itself and
// does not allow additional instances to be created

// other classes obtain a reference to the Singleton type
// by calling the GetInstance() method

public sealed class Singleton
{
    static readonly Singleton instance=new Singleton();

    // Explicit static constructor to tell C# compiler
    // not to mark type as beforefieldinit, which just
    // means that it tries to do lazy instantiation
    // (constructs itself only if really used)
    static Singleton()
    {
    }

    private Singleton()
    {
    }

    public static Singleton GetInstance()
    {
        return instance;
    }
}