How to pass singleton as generic type parameter?

Question

I have an interface of edge:

public interface IEdge<TPoint, TFactory>
    where TPoint : IPoint
    where TFactory : IEdgeFactory<TPoint>
{
    TPoint Begin { get; }
    TPoint End { get; }
    void Divide();
}

The edge can be divided those producing nested edges. New edges are created using a factory pattern:

public interface IEdgeFactory<TPoint>
    where TPoint : IPoint
{
    IEdge<TPoint> Create(TPoint begin, TPoint end)
}

I want to be able to instantiate a factory inside my IEdge implementations. Normally I would do it using i.e. public static IEdgeFactory<TPoint> Instance { get; }, but I can't define this in interface.

So is there a way to pass the singleton factory as type parameter and give implementations a way to instantiate it?

Answer 1

You can simply pass factory to classes implementing the interface:

public interface IEdge<TPoint>...

class MyEdge : IEdge<MyPoint>
{
   IEdgeFactory<MyPoint> factory;
   public MyEdge(IEdgeFactory<MyPoint> factory)
   {
      this.factory = factory;
   }
}