Commission, the callback function

class MeiTuan 
    { 
        // declare a delegate 
        public  the delegate  String OrderDelegate ( int Money, String Order); 

        public  String OrderEnter ( int Money, String Order, OrderDelegate oederDelegate) 
        { 
            // business logic 
            Store = Store new new Store (); 
            store.Receipt (Money , Order); 
            store.Finish (); 
            // can be packaged more business logic 

            return oederDelegate (Money, Order); 
        } 
    } 
class Store 
    {
        public  void the Receipt ( int Money, String Order) 
        { 
            Console.WriteLine ( " ごas rice ga ~ te su i ma ...... " ); 
        } 

        public  void Finish () 
        { 
            Console.WriteLine ( " ごrice Coming ...... .. " ); 
        } 
    } 
class PaoTui 
    { 
        // callback function [function as an argument to another function} 
        public  String BuyFood ( int mongey, String Order) 
        { 
            return  " ごっbuy rice ta ga .....";
        }

    }
class Program
    {
        static void Main(string[] args)
        {
            MeiTuan member1 = new MeiTuan();
            PaoTui brother = new PaoTui();

            string mess = member1.OrderEnter(66, "rice", brother.BuyFood);
            Console.WriteLine(mess);

            Console.ReadKey();
        }
    }

 

Original link: https: //blog.csdn.net/wxfx888/article/details/78079970

event:

         Definition: when a particular action occurs, to execute a section of code. Nature of the event is to delegate. Such as a button click event, keyboard depression event. . .

Commission:

1. Definition: A delegate is a class. It is a definition of the type of method signature. When the delegate instance, you may be instances associated with any method with a compatible signature. You can call the method through a delegate instance. Signature is a method parameters, return type.

        For example: life, if we need if a lawsuit in court by lawyers for our defense, but lawyer Barbara is executed heard the parties, this time the lawyer was a delegate object, the object is to help the parties a lawyer to defend himself.

                   However, the concept in C # objects entrusted to it like a lawyer.

       2. How to use:

　　　　I. Definitions: delegate void Mydelegate (type1 para1, type2 para2);

　　　　Second, the statement: Mydelegate d;

　　　　Third, the instantiation: d = new Mydelegate (obj.InstanceMethod); (pass a constructor method to a delegate), steps in front of a lawyer configured like object like a party methods InstanceMethod

　　　　Fourth, as a method to pass parameters: MyMethod (d); (delegate implement the method of [] obj.InstanceMethod passed as a parameter to another method MyMethod [], the object delegate is a method of packaging)

　　　　Fifth, use the delegate methods. MyMethod method is like a judge, MyMethod method first call delegate, delegate invocation method InstanceMethod, this process just as a judge for questioning to a lawyer, then certainly understand the circumstances of the case to the parties before a lawyer. C # delegate is like a lawyer, Barbara tells the merits of the parties (Barbara is called an instance method InstanceMethod)

　　　　Sixth, the commission can achieve superimposition method, the formation of the list of delegates. For example: d + = Method2 ();

　　3. Role:

　　　　First, the introduction of commission, the programmer can process references encapsulated delegate object (the calling procedure into an object invocation, fully reflects commissioned enhanced object-oriented programming ideas.), Then passed delegate object in need code that references the method, so that in the process of compiling, we do not know what to call a method, this way, C #

                      After the introduction of delegation mechanism, so that the method declaration and implement methods of separation, fully embodies the object-oriented programming ideas.

　　　　Second, I am a special class , I define the type of method (as defined in the same numeric type int, when the delegate object is instantiated with a method, the delegate represents a method, the method of this type is a delegate type ), method I may be used as the parameter to be passed to another process, the program makes it easier to expand. Namely decoupling.

　　4 illustrates a delegate

　　　　As the code, customers want to call on the US group to run errands service, just give him the money and told him what I want to buy, who do not need to know how to help me to buy the stuff.

Callback

　　The callback function is passed to a method of another way to do it. Callback function is a functional fragment, a function according to the user callback function calling conventions implemented. Delegate understood conjunction with the above codes.