delegates

问题 I have two classes Parser and Proxy , and when I invoke a method from Parser , which does not exist, it will delegate it to Proxy class. My code: class Parser { noSuchMethod(Invocation invocation) { // how to pass the `invocation` to `Proxy`??? } } class Proxy { static String hello() { return "hello"; } static String world() { return "world"; } } That when I write: var parser = new Parser(); print(parser.hello()); It will print: hello 回答1: You have to use dart:mirrors . Here's how to do :

问题 I have two classes Parser and Proxy , and when I invoke a method from Parser , which does not exist, it will delegate it to Proxy class. My code: class Parser { noSuchMethod(Invocation invocation) { // how to pass the `invocation` to `Proxy`??? } } class Proxy { static String hello() { return "hello"; } static String world() { return "world"; } } That when I write: var parser = new Parser(); print(parser.hello()); It will print: hello 回答1: You have to use dart:mirrors . Here's how to do :

问题 The documentation for converting delegates to unmanaged code states that I am responsible for preventing it's collection myself. I wish to know if the delegate cannot be collected whilst the unmanaged call is live. For example, if I do UnmanagedFunction(arg => somebody); where UnmanagedFunction does not store the function pointer beyond it's invocation. This should be legal, right? The CLR can't collect whilst the UnmanagedFunction is executing. 回答1: According to CLR Inside Out: Marshaling

问题 when we touch the tabbaritem of the tabbarcontroller the delegate methods are called: -(BOOL)tabBarController:(UITabBarController *)tabBarController shouldSelectViewController:(UIViewController *)viewController; - (void)tabBarController:(UITabBarController *)tabBarController didSelectViewController:(UIViewController *)viewController; but when try to do the same thing programmatically, i.e. [self.tabbarController setSelectedIndex:selectedIndexNo]; or [self.tabBarController

问题 Is their a way to execute a delegate or event in C# when the seconds, minutes, hours,... change in the system-clock, without using a timer that checks every millisecond if the property has changed and executes the event with a delay of maximum a millisecond. I thus want to avoid polling and fire an event at a certain time. 回答1: If your question is: "How do I execute a delegate every full second/minute/hour?" For minute and hour intervals, you could do something like shown in my answer in this

问题 I'm trying to use a series of CALayers as sublayers to a view that needs a little more fine grained drawing than usual. I've been using CATiledLayer before, and I thought using sublayers would be easier, if not equally finicky. I figured I perform a [self.layer addSublayer:sublayer] , set the delegate of that new sublayer and then I draw all I want in the drawLayer:inContext: method. But to my great surprise, my app crashes on addSubview: (without IB) or somewhere higher up the call stack

问题 I have a Navigation based view controller and in the view controller i have hidden the top navigation bar and use a custom UIView as the navigation bar. The UIView bar has a back button and I use Delegate methods(I have declared a protocol) to communicate to the view controller when the back button is preesed. I use delegate in my CustomNavigation Bar id delegate; and In the main View Controller when i allocate the navigation bar i set the delegate topBar = [[TopNavigationBar alloc]

问题 I'm working on a Windows Forms application, and it contains custom controls with methods that can potentially be called from threads other than the UI thread. So these methods therefore look a bit like this to prevent exceptions: public void DoSomeStuff() { if (InvokeRequired) { Invoke((Action)DoSomeStuff); } else { // Actually do some stuff. } } The explicit cast of the method group DoSomeStuff to an Action caught my attention, and so I've been looking into delegates and other related

问题 I have a Silverlight app that uses actions to get data from the model (which again gets the data from WCF services). I need to somehow sync two ActionCallbacks, or wait for them, and then execute some code. Example: _model.GetMyTypeList(list => { MyTypeList.AddRange(list); }); _model.GetStigTypeList(list => { StigTypeList.AddRange(list); }); doSomethingWhenBothHaveReturned(); I know I can use a counter to keep track of how many has returned, but is there not a better way to do this? EDIT:

问题 Some code I inherited has an annoying warning. It declares a protocol and then uses that to specify the delegate @protocol MyTextFieldDelegate; @interface MyTextField: UITextField @property (nonatomic, assign) id<MyTextFieldDelegate> delegate; @end @protocol MyTextFieldDelegate <UITextFieldDelegate> @optional - (void)myTextFieldSomethingHappened:(MyTextField *)textField; @end Classes which use myTextField implement the MyTextFieldDelegate and are called it with this code: if ([delegate