设计模式：装饰模式

装饰模式（Decorator）：动态地给一个对象添加一些额外的职责，就增加功能来说，装饰模式比生成子类更为灵活。

namespace Decorator
{
    public abstract class Component
    {
        public abstract void Operation();
    }
    public class ConcreteComponent:Component
    {
        public override void Operation()
        {
            Console.WriteLine("具体对象的操作");
        }
    }
    public abstract class Decorator:Component
    {
        protected Component component;
        public void SetComponent(Component component)
        {
            this.component = component;
        }
        public override void Operation()
        {
            if(component!=null)
            {
                component.Operation();
            }
        }
    }
    public class ConcreteDecoratorA:Decorator
    {
        private string addedState;
        public override void Operation()
        {
            base.Operation();
            addedState = "New State";
            Console.WriteLine("具体装饰对象A的操作");
        }
    }
    public class ConcreteDecoratorB : Decorator
    {
        public override void Operation()
        {
            base.Operation();
            AddedBehavior();
            Console.WriteLine("具体装饰对象B的操作");
        }
        private void AddedBehavior()
        {

        }
    }
}

测试代码：

            ConcreteComponent c = new ConcreteComponent();
            ConcreteDecoratorA d1 = new ConcreteDecoratorA();
            ConcreteDecoratorB d2 = new ConcreteDecoratorB();
            d1.SetComponent(c);
            d2.SetComponent(d1);
            d2.Operation();