observer-pattern

问题 I am rather new for software testing. I wonder what is the right way to make a unit testing for observer pattern? e.g. if we have the following 4 classes implemented: Subject class(attach/detach/notify), Observer interface class (update virtual method), ConcreteSubject class, and ConcreteObserver (concrete update method). how to write test tracks for each of these classes? Is there any good example to take a reference? Thanks for any inputs. 回答1: For the Subject, you can test: if the observer

问题 I have an issue. 1. I have two threads: 'worker' and 'UI' thread. 2. Worker keeps on waiting for data from server, when gets it notifies to UI thread. 3. On update UI shows Toast message on screen. Step 3 is problem as it says: android.view.ViewRoot$CalledFromWrongThreadException: Only the original thread that created a view hierarchy can touch its views. Using mHandler, runOnUIThread slows down the UI thread (UI displays webview), as I have to continuously check for data from server. 回答1:

问题 Following this post I've finally managed to capture an event by extending the Magento_Adminhtml_Controller_Action and carry out some actions before it. But now I'm trying to improve it so I can capture another event triggered on the admin panel and from there pass an array through the request variable to another event on the frontend. I've these SO questions/answers, here and here but no way I can achieve what I need. I've tested the observer code using die() to be sure that the execution

问题 When rethinking my everyday programming patterns to be more swifty , there is one, that I really struggle with: observing changes . After a lot of thinking and research I have yet to find a satisfying solution . That is one, that is easy to use, leverages the full potential of swift's strong type system, is compatible with value types and allows for static dispatch. Maybe the latter one is not possible and that's the reason why my search is unsuccessful so far. If so, I would like to know why

问题 Is there a design pattern that forms a "composite" observer/observable? I mean I have an observable A that notifies its listeners on some change. Each listener is also an observable and notifies its own listener (on some action it did which action was triggered by notification of the first observable). Is this "chaining" of observers/observables ok as design or is there a standard pattern for this? 回答1: For the chaining you mentioned, I don't see any difference. The aim of Observer pattern is

问题 I've a problem when using an observer in a fragment, I've implemented my own TextViewObserver, and I wan't to insert it in a Fragment: public class TextViewObserver extends TextView implements Observer { public TextViewObserver(Context context, AttributeSet attrs, int defStyle) { super(context, attrs, defStyle); } public TextViewObserver(Context context, AttributeSet attrs) { super(context, attrs); } public TextViewObserver(Context context) { super(context); } @Override public void update

问题 My question is really "Is the lapsed listener problem preventable in javascript?" but apparently the word "problem" causes a problem. The wikipedia page says the lapsed listener problem can be solved by the subject holding weak references to the observers. I've implemented that before in Java and it works nicely, and I thought I'd implement it in Javascript, but now I don't see how. Does javascript even have weak references? I see there are WeakSet and WeakMap which have "Weak" in their names

问题 We've got some API integrations that will periodically create shipments for orders. What I'd like to do is create an observer to also create an appropriate invoice & capture payment when this shipment is created. I have this tied to sales_order_shipment_save_after : public function autoInvoice($observer){ $shipment = $observer->getEvent()->getShipment(); $order = $shipment->getOrder(); $items = $shipment->getItemsCollection(); $qty = array(); foreach($items as $item) $qty[$item['order_item_id

问题 How can I add a KVO to the currentPlaybackTime property of a MPMoviePlayer class? 回答1: You cannot add a KVO to currentPlaybackTime since the property is not explicitly declared as KVO compatible. Instead, you could try polling the player regularly and storing the position, with code such as: - (void) BeginPlayerPolling { self.pollPlayerTimer = [NSTimer scheduledTimerWithTimeInterval:5 target:self selector:@selector(PollPlayerTimer_tick:) userInfo:nil repeats:YES]; } - (void) PollPlayerTimer

问题 I have a problem with my Observer pattern when I'm trying to update the client view based on the data that comes from the server. The code that sends messages to the client: package model; import java.io.BufferedReader; import java.io.IOException; import java.io.InputStreamReader; import java.io.PrintWriter; import java.net.Socket; public class PlayerThread extends Thread{ private BufferedReader inFromClient; private PrintWriter outToClient; private Socket socket; public PlayerThread(Socket