I asked ChatGPT to write me some code:

This was the answer I got:

Including this code fragment

public sealed class Singleton
{
  private static Singleton instance = null;
  private static readonly object padlock = new object();
  private Singleton() {}

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

Nice piece of code, taking care of lazy instantiation, and thread-safe. But I don't think ChatGPT is going to replace a well-trained developer yet. Even in this code there are optimizations, like checking for null before taking the lock:

    get
    {
      if (instance == null)
      {
        lock (padlock)
        {
          if (instance == null)
          {
            instance = new Singleton();
          }
          return instance;
        }
      }
    }  

But what I am really missing is the .NET way of implementing singleton: Let the runtime take care of this by this simple piece of code:

public sealed class Singleton
{
  private Singleton() { }

  private static Singleton Instance { get; } = new Singleton();
}

Here the static constructor will take care of lazy instantiation in a thread-safe way.