observer-pattern

问题 I'm trying to use the Observer pattern for some input stuff like so: class Observer { public: virtual void notify(Subject & o)=0; }; class Subject { public: virtual void register(Observer * o)=0; } I have two concrete Subjects (Mouse, Keyboard), with class specific functions that I want the concrete observer to call( getkeypress, getmousemotion etc). Is there any way to specialise the notify function in the concrete observer class without changing the interface, or downcasting the reference?

问题 I want to poll for changes and when a desired value is reached the Observable should complete (or wait until timeout). Right now I use the filter which works fine to wait until the desired value is reached. But I want the Observable to push events while waiting for this value. For example, I wait for the status 'success' and until the status changes to 'success' the status 'testing' is returned from my service. But since the filter is waiting for 'success', 'testing' never returns. My code

问题 I have a system comprising a C# UI, a C++/CLI mixed mode interop wrapper, and some native c++ projects. What I need to do is set up a system such that the native c++ code can send a log message, and the UI can report it. I set up a native IObservable using this as a template, but then the C# code can't be an observer. My thought was to set up another observer pattern in C++/CLI, which observes the native observer, and to let the C# implement that. I used this as a template but I'm struggling

问题 So I am learning about design patterns and I am currently studying the Observer pattern. To implement it on a raw basis, I did something like this: <?php class Subject { private $foo; private $bar; private $observers = []; public function addObserver(Observer $o) { $this->observers[] = $o; } public function removeObserver(Observer $o) { if(($key = array_search($o, $this->observers, $TRUE)) !== FALSE) { unset($this->observers[$key]); } } public function notify() { foreach ($this->observers as

问题 This application receives & forwards messages from database events to client applications. Messages are immediately delivered when the client browser has a web socket session. However, when no web socket session exists and a message is sent by the JMSProducer into the Destination "jms/notificationQueue" in QueueSenderSessionBean, the message is immediately consumed in NotificationEndpoint. This is not my intent. My intent is for the queue to retain the message until the user connects to

问题 I am creating a chat program where my chat persons are a label. the labels can be moved around on the screen when the user clicks on the anchorpane now there are two senerios here: The chatperson has to locally move. the client has to send this movement to all the other connected clients. The 2nd case is easy enough if the objects works as they should currently my ChatPerson object looks like this: package GUI; public class ChatPerson { private String username; private int x; private int y; /

问题 I'm trying to create a functionality, where when I click on a FlatButton inside an Expanded widget, its flex changes to 2 and other siblings FlatButton s flex change to 1 . import 'package:flutter/material.dart'; void main() { runApp(MyApp()); } class MyApp extends StatelessWidget { @override Widget build(BuildContext context) { return Directionality( textDirection: TextDirection.ltr, child: Column( crossAxisAlignment: CrossAxisAlignment.stretch, children: <Widget>[ new ButtonWidget(text:

问题 Im having trouble trying to get my model observer to work.. It is working as expected for create and deleted, but not for updating. Im guessing the event never fires. The thing is all of then are being done exactly the same way. Any ideas? Below, my observer. class GenericObserver extends AbstractObserver { protected $events; public function __construct(Dispatcher $dispatcher){ $this->events = $dispatcher; } public function saved($model) { dd($this->events); $user_id = Auth::user()->usr_id;

问题 I observed the dataLayer array and I don't see any changes to push . No custom methods at all, actually. How is GTM observing the changes to the array? As far as I know, changes to an Array don't throw any events, do they? Edit: I did some more research and found Google's library for interacting with the dataLayer : https://github.com/google/data-layer-helper#listening-for-messages I'll take a look at the code and maybe even answer my own question if I understand the ineer workings. 回答1:

问题 I have two entities for two classes. First is an extended class of the second (Observer pattern): The child: @Entity @Inheritance(strategy = InheritanceType.JOINED) @DiscriminatorValue("User") @Table(name="SCH.USER") public class User extends Observer implements Serializable{ ...fields... } And the father: @Entity @Inheritance(strategy = InheritanceType.JOINED) @DiscriminatorColumn(name = "DISCRIMINATOR", discriminatorType = DiscriminatorType.STRING) @Table(name="SCH.OBSERVER") public