Do fluent interfaces violate the Law of Demeter?

Question

The wikipedia article about Law of Demeter says:

The law can be stated simply as "use only one dot".

However a simple example of a fluent interface may look like this:

static void Main(string[] args)
{
   new ZRLabs.Yael.Pipeline("cat.jpg")
        .Rotate(90)
        .Watermark("Monkey")
        .RoundCorners(100, Color.Bisque)
        .Save("test.png");
}

So does this goes together?

Answer 1

Well, the short definition of the law shortens it too much. The real "law" (in reality advice on good API design) basically says: Only access objects you created yourself, or were passed to you as an argument. Do not access objects indirectly through other objects. Methods of fluent interfaces often return the object itself, so they don't violate the law, if you use the object again. Other methods create objects for you, so there's no violation either.

Also note that the "law" is only a best practices advice for "classical" APIs. Fluent interfaces are a completely different approach to API design and can't be evaluated with the Law of Demeter.