Visibility of nested class constructor

Question

Is there a way to limit the instantiation of the nested class in C#? I want to prevent nested class being instantiated from any other class except the nesting class, but to allo

Answer 1

Since there is nothing in C# syntax you'll have to implement something like "a contract" between them. You can take advantage of the fact that nested class can access private fields of its parent:

public class ParentClass
{
  private static Func _friendContract;

  public class FriendClass
  {
      static FriendClass()
      {
          _friendContract= () => new FriendClass();
      }

      private FriendClass() { }
  }

  ///Usage
  public FriendClass MethodUse()
  {
      var fInstance = _friendContract();
      //fInstance.DoSomething();
      return fInstance;
  }
}

Of course you can adjust the contract to handle different parameters

 private static Func _friendContract;