Question

I am trying to strongly type an object property that has been defined as an interface in an interface. Here is my sample

// interfaces
public interface IMyInterfaceA
{
    string A { get; set; }
    IMyInterfaceB B { get; set; }
}

public interface IMyInterfaceB
{
    string B { get; set; }
}

// POCOs
public class pocoOneB : IMyInterfaceB
{
    public B { get; set; }
    public C { get; set; }  // extending the poco with a non-interfaced property
}

public class pocoOneA : IMyInterfaceA
{
    string A { get; set; }
    pocoOneB B { get; set; }  // fails, can I strongly type an interface??
}

public class pocoTwoB : IMyInterfaceB
{
    public B { get; set; }
    public D { get; set; }  // extending the poco with a non-interfaced property
}

public class pocoTwoA : IMyInterfaceA
{
    string A { get; set; }
    pocoTwoB B { get; set; } // fails, can I strongly type an interface??
}

The problem is I can’t do

pocoOneB B { get; set; } // fails, can I strongly type an interface??

or

pocoTwoB B { get; set; } // fails, can I strongly type an interface??

even though they are implementations of the interface, the compiler says I didn’t correctly implement IMyInterfaceA on either poco. I understand the error, however I would like to know if there is a way to strongly type a property that has an interface?

One way around this is to not have the interface IMyInterfaceA define a property of interface IMyInterfaceB at all and extent on the poco’s, however I am trying to enforce the property is implemented using interfaces.

The main reason I need to strongly type the properties of the poco is because I am using JSON to desterilize over the wire.

Thank you for any guidance.

Answer 1

public interface IMyInterfaceA<TPoco>
   where TPoco : IMyInterfaceB
{     
   TPoco B { get; set; } 
} 

public class pocoOneA<TPoco> : IMyInterfaceA<TPoco>
  where TPoco : IMyInterfaceB
{     
   public TPoco B { get; set; }  // fails, can I strongly type an interface?? 
} 

or simply

public interface IMyInterfaceA
{     
   IMyInterfaceB B { get; set; } 
} 

public class pocoOneA : IMyInterfaceA
{     
   public IMyInterfaceB B { get; set; }  // fails, can I strongly type an interface?? 
}