c# - Type Casting and the Factory pattern

Question

I'm having a hard time figuring out how to implement a factory pattern in a DTO mapper I'm trying to create. I'm pretty sure I need to rethink my design. Here is a very small example of what I'm running in to:

    public abstract class Person
{
    public string Name { get; set; }
    public decimal Salary { get; set; }
}

public class Employee : Person
{
    public Employee()
    {
        this.Salary = 20000;
    }

}

public class Pilot : Person
{
    public string PilotNumber { get; set; }

    public Pilot()
    {
        this.Salary = 50000;
    }
}

public static class PersonFactory
{
    public static Person CreatePerson(string typeOfPerson)
    {
        switch (typeOfPerson)
        {
            case "Employee":
                return new Employee();
            case "Pilot":
                return new Pilot();
            default:
                return new Employee();
        }
    }
}

and to use the factory:

Person thePilot = PersonFactory.CreatePerson("Pilot");
        ((Pilot)thePilot).PilotNumber = "123ABC";

How do I get around loading the pilot number without typecasting it to Pilot?? is this the wrong way to do this? I could put the pilot number in the Person class, but then Employee would inherit the number and that's not what I want. What can I do?

Thanks!

-Jackson

Answer 1

The factory pattern is best used when the objects differ in implementation, not interface. In your case the factory pattern is not too beneficial, and you are probably better off creating your objects directly (or some other pattern maybe better).