Is this still a factory method?

Question

What if I don't need a special factory class and I want a concrete client to instantiate right parts. The client needs to call Hello() from that part. Everywhere else the focus is on making the factory method a method of a special creator class. But here it is right away in a client. Is this still a factory method pattern and is it even correct to use it as shown below?

using System;

namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            AClient c1 = new ClientUsingPart1();
            c1.Foo();
            AClient c2 = new ClientUsingPart2();
            c2.Foo();
            Console.ReadKey();
        }
    }

    abstract class AClient
    {
        public AClient() { this.ipart = Create(); }

        public void Foo() { ipart.Hello(); }
        // many other methods
        // ...
        public abstract IPart Create();  // factory method
        IPart ipart;
    }

    class ClientUsingPart1 : AClient
    {
        public override IPart Create() { return new Part1(); }
    }

    class ClientUsingPart2 : AClient
    {
        public override IPart Create() { return new Part2(); }
    }

    interface IPart
    {
        void Hello();
    }

    class Part1 : IPart
    {
        public void Hello() { Console.WriteLine("hello from part1"); }
    }
    class Part2 : IPart
    {
        public void Hello() { Console.WriteLine("hello from part2"); }
    }

}

score 0 · Answer 1 · edited May 23 '17 at 12:02

0

Depending on exactly what you need to achieve you should probably use some for of dependency injection with an IoC container of your choice; with StructureMap, Autofac, Unit, Ninject, Castle Windsor all very popular. Once you IoC container has built the concrete classes it should support a syntax like this

foreach (var client in Container.Resolve<IEnumerable<AClient>>())
{
    client.Create();
}

You can read more about how to achieve this with StructureMap here: Does an abstract class work with StructureMap like an interface does?

edited May 23 '17 at 12:02

Community

1
1

answered Jul 21 '12 at 11:28

Kane

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I'll look into StructureMap but I'd like to know answers to my actual questions. Most of all it still a valid factory-method pattern example? – Firkraag Jul 21 '12 at 12:57

score 0 · Accepted Answer · edited May 23 '17 at 10:34

According to this: Differences between Abstract Factory Pattern and Factory Method It seems the code I posted in the original post shows a valid use of the factory method pattern. The key is - factory method is just a method of the class - which also may be the sole client of the created objects.

Or in another way: factory method does not need to be public and provide the created objects to the outside world. In my example the Create() method should be protected.

Is this still a factory method?

2 Answers2