Replace conditional with Polymorphism

namespace RefactoringLib.Ploymorphism.Before

{

    public class Customer { }

    

    public class Employee : Customer { }

    

    public class NonEmployee : Customer { }

    

    public class OrderProcessor

    {

        public decimal ProcessOrder(Customer customer, IEnumerable<Product> products)

        {

            decimal orderTotal = products.Sum(p => p.Price);

            

            Type customerType = customer.GetType();

            if (customerType == typeof(Employee))

            {

                orderTotal -= orderTotal * 0.15m;

            }

            else if (customerType == typeof(NonEmployee))

            {

                orderTotal -= orderTotal * 0.05m;

            }



            return orderTotal;

        }

    }

}

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namespace RefactoringLib.Ploymorphism.End

{

    public abstract class Customer

    {

        public abstract decimal DiscountPercentage { get; }

    }



    public class Employee : Customer

    {

        public override decimal DiscountPercentage

        {

            get

            {

                return 0.15m;

            }

        }

    }



    public class NonEmployee : Customer

    {

        public override decimal DiscountPercentage

        {

            get

            {

                return 0.05m;

            }

        }

    }



    public class OrderProcessor

    {

        public decimal ProcessOrder(Customer customer, IEnumerable<Product> products)

        {

            decimal orderTotal = products.Sum(p => p.Price);



            orderTotal -= orderTotal * customer.DiscountPercentage;



            return orderTotal;

        }

    }



}

View Code

 

参考：Refactoring Day 31 : Replace Conditional with Polymorphism