Factory Method vs Abstract Factory

factory-patterns.cs

using System;

namespace ClassLibrary3
{
    public interface IProduct
    {
    }

    public class Foo : IProduct
    {
    }

    public class Bar : IProduct
    {
    }

    /*
     * Factory Method 패턴: 상속(Inheritance)기반
     * - 인스턴스 만드는 일을 서브클래스에게 위임
     */
    public abstract class ProductServiceByFactoryMethod
    {
        public void Display()
        {
            IProduct product = CreateProduct();
            Console.WriteLine(product.ToString());
        }

        public abstract IProduct CreateProduct();
    }

    public class FooService : ProductServiceByFactoryMethod
    {
        public override IProduct CreateProduct()
        {
            return new Foo();
        }
    }

    public class BarService : ProductServiceByFactoryMethod
    {
        public override IProduct CreateProduct()
        {
            return new Bar();
        }
    }

    /* 
     * Abstrac Factory 패턴: 구성(Composition)기반
     */
    public interface IProductFactory
    {
        IProduct Create();
    }

    public class FooFactory: IProductFactory
    {
        public IProduct Create()
        {
            return new Foo();
        }
    }

    public class BarFactory: IProductFactory
    {
        public IProduct Create()
        {
            return new Bar();
        }
    }

    public class ProductServiceByAbstractFactory
    {
        public ProductServiceByAbstractFactory(IProductFactory factory)
        {
            if(factory == null)
                throw new ArgumentNullException(nameof(factory));
                
            Factory = factory;
        }

        public IProductFactory Factory { get; }

        public void Display()
        {
            IProduct product = Factory.Create();
            Console.WriteLine(product.ToString());
        }
    }
}