Creating a cloned copy of subclass from baseclass

Question

Consider this scenario:

public class Base
{
    public int i;
}

public class Sub : Base
{
    public void foo() { /* do stuff */}
}

And th

Answer 1

Per the "Gang of Four" : "Favor composition over inheritance" and this is a perfect reason to do so...

If we have a SuperClass that looks like this:

public class SuperClass : Person 

The SuperClass can easily decorate the Person class adding properties not found in Person class. But what happens if the Superclass decorations are only for the GUI? For example a bool value indicating "Selected". We are still able to get all Persons from the DB in a List but we run into trouble trying to create the Superclass and merge the DB results.

    foreach( var person in myPersonList){
    var sc = new SuperClass();
    sc.Selected = false;
    sc=person;
 }

The compiler complains because Superclass is not a Person to the compiler it's a Superclass. The only way to fill in the properties of the Person subclass is to iterate and set each one... like this.

    SuperClass.Name = Person.Name;
    SuperClass.Id = Person.ID;  

Pretty tedious indeed. But there's a better way.... Don't make Superclass inherit from Person

public class SuperClass{
  public Person ThisPerson {get;set;}
  public bool Selected {get;set;}
}

This gives us "Containment" The Superclass now contains a Person class.

Now we can do this:

foreach(var person in MyPersonList){
   var sc = new Superclass();
   sc.Selected = false;
   sc.Person = person;
}

The consumer of this class must now qualify the properties of the Superclass/Person like this...

forach(var sc in MySuperClassList){
  var selected = sc.Selected;
  var name = sc.Person.Name;
}

The beauty of this is that in the future, you can add any other container you want and it will NOT affect any other containers. You can also morph the Superclass to anything it contains. If each of the contained classes become Interfaces, then that's one step futher down the road.