// Lang_33 [interfaces II].nova
// Show that an interface does not get broken with inheritance.


// The application class.
class InterfacesIIApp
{
   // Application class's "main" function.
   public static void main( String[] args )
   {
      Stream.writeLine( "App.main( ) - called" );

      // Create a new object using a concrete class and assign to an interface reference.
      IFourMethods a = new ConcreteClass2( );

      // Call a virtual method using the abstract class reference.
      a.m0( );

      // Call a virtual method using the abstract class reference.
      a.m1( );

      // It is not possible to instantiate a new object using an abstract class.
//      AbstractClass abstractClass = new AbstractClass( );
   }
}



// Declare an example interface with four methods.
interface IFourMethods
{
   public void m0( );
   public void m1( );
   public void m2( );
   public void m3( );
}



// Declare an extra interface.
interface IExtra
{
   public void extraMethod( );
}



// Concrete class.
class ConcreteClass
{
   public virtual void m1( )
   {
      Stream.writeLine( "ConcreteClass.m1( ) - called" );
   }
}



// Concrete class 2.
class ConcreteClass2 : ConcreteClass, IFourMethods, IExtra, IRun
{
   public virtual void m0( )
   {
      Stream.writeLine( "ConcreteClass2.m0( ) - called" );
   }

   public virtual void m2( )
   {
      Stream.writeLine( "ConcreteClass2.m2( ) - called" );
   }

   public virtual void m3( )
   {
      Stream.writeLine( "ConcreteClass2.m3( ) - called" );
   }

   public virtual void extraMethod( )
   {
      Stream.writeLine( "ConcreteClass2.extraMethod( ) - called" );
   }

   public virtual Object run( Object arg )
   {
      Stream.writeLine( "ConcreteClass2.run( ) - called" );

      return null;
   }
}