装饰模式(Decorator)

个人理解：

装饰模式的精髓在于装饰基类定义了一个装饰类基类类型的字段。

UML类图

代码实现：

using System;

namespace DecoratorMode
{
    class Program
    {
        static void Main(string[] args)
        {
            Hero hero = new Hero();

            KillLion killLion1 = new KillLion();
            KillSteven killSteven1 = new KillSteven();
            KillLion killLion2 = new KillLion();
            KillSteven killSteven2 = new KillSteven();

            killLion1.AddKillRecord(hero);
            killSteven1.AddKillRecord(killLion1);
            killSteven2.AddKillRecord(killSteven1);
            killLion2.AddKillRecord(killSteven2);

            killLion2.ShowRecord();
        }
    }


    public class Hero
    {
        public virtual void ShowRecord()
        {
            Console.WriteLine("心灵捕手随机选择了猴子...");
        }
    }

    public class KillBase : Hero
    {
        protected Hero currentHero;

        public void AddKillRecord(Hero hero)
        {
            this.currentHero = hero;
        }

        public override void ShowRecord()
        {
            if (currentHero != null)
                currentHero.ShowRecord();
        }
    }

    public class KillLion : KillBase
    {
        public override void ShowRecord()
        {
            this.currentHero.ShowRecord();
            Console.WriteLine("莱恩被心灵捕手的猴子给击杀了...");
        }
    }

    public class KillSteven : KillBase
    {
        public override void ShowRecord()
        {
            this.currentHero.ShowRecord();
            Console.WriteLine("Steven被心灵捕手的猴子给击杀了...");
        }
    }
}

装饰类的Python实现代码:

class BaseLogger:
    Info=""
    Error=""
    Warning=""
    def WriteLog(self):
        raise NotImplementedError("Abstract")

'''装饰模式的精髓在于装饰基类定义了一个装饰类基类类型的字段。'''
class Logger(BaseLogger):
    __logger=None
    def SetLogger(self, logger):
        self.__logger=logger
    def WriteLog(self):
        if(self.__logger!=None):
            self.__logger.WriteLog()
        if(self.Info!=""):
            print(self.Info)
        elif(self.Error!=""):
            print(self.Error)
        elif(self.Warning!=""):
            print(self.Warning)
        else:
            pass

class SystemALogger(Logger):
    pass

class SystemBLogger(Logger):
    pass

systemALogger1=SystemALogger()
systemBLogger1=SystemBLogger()
systemALogger1.Info="Current is running in System A."
systemALogger2=SystemALogger()
systemALogger2.SetLogger(systemALogger1)
systemALogger2.Error="System A crashed."
systemBLogger1.SetLogger(systemALogger2)
systemBLogger1.Info="Current is running in System B."
systemBLogger1.WriteLog()