Singleton

Pour le c#

Version super simplifié

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

private Singleton()
{

}

public static Singleton Instance
{
get
{
return Instance;
}
}
}

Version (mono-thread)

public class Singleton
{
    private static Singleton instance;

    private Singleton()
    {
    }

    public static Singleton Instance
    {
        get
        {
            if (instance == null)
            {
                instance = new Singleton();
            }
            return instance;
        }
    }
}

Version (multi-threads)

public class Singleton
{
    private static Singleton instance;
    static readonly object instanceLock = new object();

    private Singleton()
    {
    }

    public static Singleton Instance
    {
        get
        {
            if (instance == null)
            {
                lock (instanceLock)
                {
                   if (instance == null)
                   instance = new Singleton();
                }
            }
            return instance;
        }
    }
}

Version (multi-threads) - Autre implémentation possible, depuis le .Net 4, sans lock

f

public class Singleton
{
    private static readonly Lazy<Singleton> lazy = new Lazy<Singleton>(() => new Singleton());

    public static Singleton Instance { get { return lazy.Value; } }

    private Singleton()
    {
    }
}