- Posted by dan on August 4, 2011
So What is a Factory Method?
The Factory method is another Creational pattern. It's basically concerned with newing up your objects. It might be that you create a lot of FordFiesta objects and quite a lot of FordFocus objects. You might create these all over your program. Then something happens and you make a change to one of the types. This might lead to you having to go through and update every piece of code where you've gone var car = new FordFocus()
Why do I need a Factory Method?
There's a lot of duplication in all those new Cars. To remove the code duplication and therefore improve encapsulation we can defer all object creation of to a Factory specifically maybe a particular Factory Method for example FordFiestaFactory.CreateCar().
This also means that everyone only need depend on the abstraction, which makes eveything just that little more flexible.
Factory Method at a glance
Factory Method Code Examples
namespace FactoryMethod
{
public class FordFiestaCarFactory : ICarFactory
{
public ICar CreateCar()
{
return new FordFiesta();
}
}
}
Above is the Factory itself, with the program using it shown below.
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
namespace FactoryMethod
{
class Program
{
Program(ICarFactory carFactory)
{
var car = carFactory.CreateCar();
car.Drive();
}
static void Main(string[] args)
{
new Program(new FordFiestaCarFactory());
new Program(new FordFocusCarFactory());
Console.WriteLine("--------------");
Console.ReadLine();
}
}
}
Recommended Reading
As before in my Abstract Factory post I'd recommend Head First Design Patterns
as a really understandable guide to design patterns.
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