事件（event）设计准则（二）

 

class PubEventArgs : EventArgs
    ...{
        private readonly string m_magazineName;
        private readonly DateTime m_pubDate;
        public PubEventArgs(string magazineName, DateTime pubDate)
        ...{
            m_magazineName = magazineName;
            m_pubDate = pubDate;
        }
        public string magazineName
        ...{
            get ...{ return m_magazineName; }
        }
        public DateTime pubDate
        ...{
            get ...{ return m_pubDate; }
        }
    }
    class Publisher
    ...{
        public delegate void PubComputerEventHandler(object sender,PubEventArgs e);//statement of the event for agents
        public delegate void PubLiftEventHandler(object sender, PubEventArgs e);
        public event PubComputerEventHandler PubComputer;//event of statement
        public event PubLiftEventHandler PubLife;
        protected virtual void OnPubComputer(PubEventArgs e)
        ...{
            PubComputerEventHandler handler = PubComputer;
                if(handler!=null)
                ...{
                    handler(this, e);
                }
        }
        protected virtual void OnPubLife(PubEventArgs e)
        ...{
            PubLiftEventHandler handler = PubLife;
            if (handler != null)
            ...{
                handler(this, e);
            }
        }
        public void issueComputer(string magazineName,DateTime pubDate)//method of trigger event
        ...{
            Console.WriteLine("issue "+magazineName);
            OnPubComputer(new PubEventArgs(magazineName, pubDate));
        }
        public void issueLife(string magaineName,DateTime pubDate)
        ...{
            Console.WriteLine("issue " + magaineName);
            OnPubLife(new PubEventArgs(magaineName, pubDate));
        }
    }
    class Subscriber
    ...{
        private string name;
        public Subscriber(string name)
        ...{
            this.name = name;
        }
        public void Reveive(object sender ,PubEventArgs e)//define in the event subscribers procedure of handing event
        ...{
            Console.WriteLine(e.pubDate+" "+name + " have already received " + e.magazineName);
        }
    }
    class EventTest
    ...{
        static void Main()
        ...{
            Publisher pub = new Publisher();
            Subscriber sam = new Subscriber("Sam");
            pub.PubComputer += new Publisher.PubComputerEventHandler(sam.Reveive);//Subscriber to the event issuers an event
            Subscriber Jone = new Subscriber("Jone");
            pub.PubComputer += new Publisher.PubComputerEventHandler(Jone.Reveive);
            pub.PubLife += new Publisher.PubLiftEventHandler(Jone.Reveive);
            pub.issueComputer("computer magazine",Convert.ToDateTime("2006-1-1"));//trigger event
            pub.issueLife("Life magazine", Convert.ToDateTime("2006-1-1"));
            Console.WriteLine();
            Console.WriteLine("one year ago");
            pub.PubComputer -= new Publisher.PubComputerEventHandler(Jone.Reveive);
            pub.issueComputer("computer magazine", Convert.ToDateTime("2007-1-1"));
            pub.issueLife("Life magazine", Convert.ToDateTime("2007-1-1"));
        }
    }

一个程序用两种方式写

没有按准则写

     class Publisher
    ...{
        public delegate void PubComputer(string magazineName);//statement of the event for agents
        public delegate void PubLift(string magazineName);
        public event PubComputer OnPubComputer;//event of statement
        public event PubLift OnPubLife;
        public void issueComputer()//method of trigger event
        ...{
            if (OnPubComputer != null)
            ...{
                Console.WriteLine("issue <<Programs>> magazine");
                OnPubComputer("Computer magazine");
            }
        }
        public void issueLife()
        ...{
            if (OnPubLife != null)
            ...{
                Console.WriteLine("issue <<Life>> magazine");
                OnPubLife("Life magazine");
            }
        }
    }
    class Subscriber
    ...{
        private string name;
        public Subscriber(string name)
        ...{
            this.name = name;
        }
        public void Reveive(string magazineName)//define in the event subscribers procedure of handing event
        ...{
            Console.WriteLine(name+" have already received "+magazineName);
        }
    }
    class EventTest
    ...{
        static void Main()
        ...{
            Publisher pub = new Publisher();
            Subscriber sam = new Subscriber("Sam");
            pub.OnPubComputer += new Publisher.PubComputer(sam.Reveive);//Subscriber to the event issuers an event
            Subscriber Jone = new Subscriber("Jone");
            pub.OnPubComputer += new Publisher.PubComputer(Jone.Reveive);
            pub.OnPubLife += new Publisher.PubLift(Jone.Reveive);
            pub.issueComputer();//trigger event
            pub.issueLife();
            Console.WriteLine();
                Console.WriteLine("one year ago");
                pub.OnPubComputer -= new Publisher.PubComputer(Jone.Reveive);
                pub.issueComputer();
                pub.issueLife();
        }
    }

按准则写：