大话设计-装饰模式

装饰模式的核心：被装饰对象（最原始），装饰对象（带有装饰功能的被装饰对象）。

假设有一个被装饰对象叫“ConcreteComponent ”，两个装饰对象叫“ConcreteDecoratorA”、“ConcreteDecoratorB”。装饰是锦上添花的事情，ConcreteComponent 被装饰之前已经最好了最基本的工作，ConcreteDecoratorA和ConcreteDecoratorB只是在这个基本工作里额外加了些工作。

装饰是无序的，可以ConcreteDecoratorA先装饰ConcreteComponent，然后ConcreteDecoratorB装饰ConcreteDecoratorA。也可以ConcreteDecoratorB先装饰ConcreteComponent，然后ConcreteDecoratorA装饰ConcreteDecoratorB。

被装饰对象和装饰类是否需要抽象跟这里的装饰模式无关。

using System;

namespace ConsoleApp4
{
    class Program
    {
        public static void Main(string[] args)
        {
            ConcreteComponent concreteComponent = new ConcreteComponent();
            ConcreteDecoratorA concreteDecoratorA = new ConcreteDecoratorA();
            ConcreteDecoratorB concreteDecoratorB = new ConcreteDecoratorB();

            concreteDecoratorA.SetComponent(concreteComponent);
            concreteDecoratorB.SetComponent(concreteDecoratorA);
            concreteDecoratorB.Operation();
        }
    }
    
    abstract class Component
    {
        public abstract void Operation();
    }

    class ConcreteComponent:Component
    {
        public override void Operation()
        {
            Console.WriteLine("具体对象的操作");
        }
    }

     abstract class Decorator : Component
    {
        protected Component component;
        public void SetComponent(Component component)
        {
            this.component = component;
        }
        public override void Operation()
        {
            if (component != null)
            {
                component.Operation();
            }
        }
    }

     class ConcreteDecoratorA : Decorator
    {
        private string addState;
        public override void Operation()
        {
            base.Operation();
            addState = "A addState";
            Console.WriteLine("A类装饰");
        }
    }

    class ConcreteDecoratorB : Decorator
    {
        private string addState;
        public override void Operation()
        {
            base.Operation();
            addState = "B addState";
            Console.WriteLine("B类装饰");
        }
    }
}

using System;

namespace ConsoleApp4
{
    class Program
    {
        public static void Main(string[] args)
        {            
            Person person = new Person("白石");
            TShirts shirts = new TShirts();
            Overalls overalls = new Overalls();

            shirts.Decorate(person);
            overalls.Decorate(shirts);
        }
    }
    
   class Person
    {
        public Person()
        {

        }
        private string name;
        public Person (string name)
        {
            this.name = name;
        }
        public virtual void Show()
        {
            // 什么装饰都没有的基本展示。
            Console.WriteLine($"{name} 一个人的基本show");
        }
    }

    abstract class Finery : Person
    {
        protected Person component;
        public void Decorate(Person person)
        {
            this.component = person;
        }
        public override void Show()
        {
            if (component != null)
            {
                component.Show();
            }
        }
    }

    class TShirts : Finery
    {
        public override void Show()
        {
            base.Show();
            Console.WriteLine("穿T恤");
        }
    }

    class Overalls : Finery
    {
        public override void Show()
        {
            base.Show();
            Console.WriteLine("工装裤");
        }
    }
}