Template methord

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace ConsoleApplication3
{
    abstract class EvenNumberGenerator
    {
        public void Run(int min, int max)
        {
            for (int i = min; i < max; i++)
            {
                if ((i % 2) == 0)
                {
                    ProcessNumber(i);
                }
            }
        }
        public abstract void ProcessNumber(int number);
    }
    class ConsoleEvenNumberPrint : EvenNumberGenerator
    {
        public override void ProcessNumber(int number)
        {
            Console.WriteLine("From console print, number{0}", number);
        }
    }
    class FileEvenNumberPrint : EvenNumberGenerator
    {
        public override void ProcessNumber(int number)
        {
            Console.WriteLine("From File print: number{0}", number);
        }

    }
    class Program
    {
        static void Main(string[] args)
        {
            ConsoleEvenNumberPrint _consolePrint = new ConsoleEvenNumberPrint();
            _consolePrint.Run(0, 100);
            FileEvenNumberPrint _filePrint = new FileEvenNumberPrint();
            _filePrint.Run(200, 300);
            Console.ReadKey();
        }
    }
}

两个继承类都需要一样的方法，所以EvenGenerator被提到父类上做reuse code。记得abstract class不可以instantiate，所以一定要继承类才可以call EventGenerator。但同时两个类的print功能不一样，但是是共性的，所以用abstract方法提到上面，各自的类写自己的实现过程。

考虑：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace ConsoleApplication5
{
    abstract class Person
    {
        public void AddFingerNailToLength()
        {
            var numberOfNail = GetFingerNailLength()*5;
            for (int i = 0; i < numberOfNail; i++)
            {
                Console.WriteLine("Add fingernail {0}", i);
            }
        }
        public int GetFingerNailLength()
        {
            return 2;
        }
    }
    class Empoyee : Person
    {
        //Empoyee有10个fingernail，要怎么implemented？

    }
    class Janitor : Person
    {
        //Janitor有3个fingernail，要怎么implemented？
    }
    class Program
    {
        static void Main(string[] args)
        {
            var people = new List<Person>();
            people.Add(new Empoyee());
            people.Add(new Janitor());
            foreach (var item in people)
            {
                item.AddFingerNailToLength();   //这里是对的，我们没有实例化Person对象，而是他的继承对象
            }
            Console.ReadKey();
        }
    }
}

我们要继承类分别有不一样的fingernail该怎么办呢？换成Template methord。由主类来叫一个methord，methord对应不同的继承类不同

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace ConsoleApplication5
{
    abstract class Person
    {
        public void AddFingerNailToLength()
        {
            var numberOfNail = GetFingerNailLength()*5;
            for (int i = 0; i < numberOfNail; i++)
            {
                Console.WriteLine("Add fingernail {0}", i);
            }
        }
        abstract public int GetFingerNailLength();
       //改之前的这个方法为abstract， 相当于一个继承类的方法的模板了
    }
    class Empoyee : Person
    {
        public override int GetFingerNailLength()
        {
            return 5;
        }

    }
    class Janitor : Person
    {
        public override int GetFingerNailLength()
        {
            return 1;
        }
    }
    class Program
    {
        static void Main(string[] args)
        {
            var people = new List<Person>();
            people.Add(new Empoyee());
            people.Add(new Janitor());
            foreach (var item in people)
            {
                item.AddFingerNailToLength();   //这里是对的，我们没有实例化Person对象，而是他的继承对象
            }
            Console.ReadKey();
        }
    }
}