delegates

问题 I am trying to create a protocol for JSON loading delegation, JSONLoaderDelegate . My other class, called JSONLoader , is supposed to dispatch events to its delegate (that implements the JSONLoaderDelegate protocol) like: self?.delegate?.jsonLoaderdidEndWithError(self!, error: JSONLoaderError.LoadError) The implementation of the JSONLoader is not that important (imho). However I seem to have problems to implement the protocol, this is the code: @objc protocol JSONLoaderDelegate { optional

问题 I'm a very new to C#. Just playing around with it. Not for a real purpose. void makeOutput( int _param) { Console.WriteLine( _param.ToString()); } //... // Somewhere in a code { makeOutput( /* some not c# code for an example for what do I want */ function : int () { return 0; } ); } Is it possible to use a REAL anonymous functions (means returning result)? I do not want to use delegates such as // Somewhere in a code { Func<int> x = () => { return 0; }; makeOutput( x()) } Also I DO NOT want

问题 Background Given that 'most' developers are Business application developers, the features of our favorite programming languages are used in the context of what we're doing with them. As a C# / ASP.NET Application developer, I tend to only use delegates when dealing with UI events. In fact (and this is part of my inexperience showing), I don't even know a good context other than events to use delegates in! This is quite scary; but I'm gathering that there are other developers in the same boat.

问题 Why is it necessary to make a function STATIC while using delegates in C# ? class Program { delegate int Fun (int a, int b); static void Main(string[] args) { Fun F1 = new Fun(Add); int Res= F1(2,3); Console.WriteLine(Res); } **static public int Add(int a, int b)** { int result; result = a + b; return result; } } 回答1: It's not "necessary". But your Main method is static , so it can't call a non- static method. Try something like this (this isn't really a good way to do things—you really

问题 Why does this not work? Do I not understand delegate covariance correctly? public delegate void MyDelegate(object obj) public class MyClass { public MyClass() { //Error: Expected method with 'void MyDelegate(object)' signature _delegate = MyMethod; } private MyDelegate _delegate; public void MyMethod(SomeObject obj) {} } 回答1: Correct - you don't understand covariance correctly - yet :) Your code would work if you had the same types but as return values, like this: public delegate object

问题 i am attempting to attach a Delegate to an invocation list of a different delegate. By that i am achieving a kind of Hook on existing events. I need to hook up something that runs after each event that is invoked. The following example works as long as the Delegate exposed by the type and the Action i pass in have the exact same signature. (On1 and OnAll events are both declared with an Action delegate so it works). Code : How i hook up an Action with an existing delegate exposed by an event

问题 My delegate protocol never called My first controller - ViewController class ViewController: UIViewController,testProtocol { @IBAction func btInit(sender: AnyObject) { println("Bt Init") let storyBoard : UIStoryboard = UIStoryboard(name: "Main", bundle: nil) let initViewController: UIViewController = storyBoard.instantiateViewControllerWithIdentifier("viewTarget") as targetViewController self.presentViewController(initViewController,animated: false, nil) } var targetController =

问题 Lets imagine simple delegate calls: void Main() { Func<int, int, string> tfunc = null; tfunc += Add; // bind first method tfunc += Sub; // bind second method Console.WriteLine(tfunc(2, 2)); } private string Add(int a, int b) { return "Add: " + (a + b).ToString(); } private string Sub(int a, int b) { return "Sub: " + (a - b).ToString(); } The result of this program is: Sub: 0 So, why Add method was not called? I'm expecting to call Method Add, and then method Sub. 回答1: Add was correctly

问题 I know that the += operator will add a method to the invocation list maintained by the Delegate base object, for example using System; class Program { delegate void MyDelegate(int n); void Foo(int n) { Console.WriteLine("n = {0}", n) } static void Main(string[] args) { MyDelegate d = new MyDelegate(Foo); d += Foo; // add Foo again d.Invoke(3); // Foo is invoked twice as Foo appears two times in invocation list } } But when I look at MSDN Delegate, MulticastDelegate I can't find any definition

问题 I have a need to do some real-time reporting on the functionality of a WCF service. The service is self-hosted in a windows app, and my requirement is to report "live" to the host app when certain methods are called by the client. My initial thought on the task was to publish a "NotifyNow" event in the service code, and subscribe to the event in my calling app, but this doesn't seem to be possible. Within my service code (implementation, not the interface) I have tried adding the following