observer-pattern

问题 Context: I am trying to implement something like OOP observable pattern in OCaml with using first-class modules. I have a project with a list of modules and want to extend them with observation without changing. To minimize code duplication I created Subject module and plan to use it as a part of the common way (in the project context) for this extending. I declared three module types: OBSERVER: module type OBSERVER = sig type event type t val send : event -> t -> t end OBSERVABLE: module

问题 Context: I am trying to implement something like OOP observable pattern in OCaml with using first-class modules. I have a project with a list of modules and want to extend them with observation without changing. To minimize code duplication I created Subject module and plan to use it as a part of the common way (in the project context) for this extending. I declared three module types: OBSERVER: module type OBSERVER = sig type event type t val send : event -> t -> t end OBSERVABLE: module

问题 I am using Android databinding to listen to live data changes and I would like to observe changes on the viewmodel level (Rather then observing on fragment and then sending a callback to the viewmodel) The observerForever is interesting as it serves the purpose for me. However when I run a test I get the following error: java.lang.NullPointerException at androidx.arch.core.executor.DefaultTaskExecutor.isMainThread(DefaultTaskExecutor.java:77) at androidx.arch.core.executor.ArchTaskExecutor

问题 I want to implement an Observer of a Model class which does not change the Model. Thus, it should be able to use a const-Reference to access the Model. But the Registering of the Observer prohibits this. Here is how the observer pattern is implemented in my Project: //Attributes of type Observable are used by classes that want to notify others //of state changes. Observing Objects register themselves with AddObserver. //The Observable Object calls NotifyObservers when necessary. class

问题 I am currently using rails 3.0.7 and ruby 1.9.2 and making a rails App which contains a video being loaded from a database while being rendered by FlowPlayer. and a set of slides based on the video. Now, I wanted to synchronize the slides with the video. For the timings, I am asking the user to enter the timings of each slide. So, I was wondering if i could use observer pattern for this by making a sort of central time as the subject and the video and slides as the observers? While, the

问题 I'm trying to reverse engineer how facebook handles their notifications, where when you get a message you get instantly notified via the browser. I've fiddled with it for a little bit and realized that there is always a pending GET request "listening" if you will to some sort of update from the server. This appears to be some sort of observer pattern. I was just wondering if this pattern was documented somewhere. 回答1: The technique is actually called Long Polling. This is one of the popular

问题 I'm trying to reverse engineer how facebook handles their notifications, where when you get a message you get instantly notified via the browser. I've fiddled with it for a little bit and realized that there is always a pending GET request "listening" if you will to some sort of update from the server. This appears to be some sort of observer pattern. I was just wondering if this pattern was documented somewhere. 回答1: The technique is actually called Long Polling. This is one of the popular

问题 I'm trying to reverse engineer how facebook handles their notifications, where when you get a message you get instantly notified via the browser. I've fiddled with it for a little bit and realized that there is always a pending GET request "listening" if you will to some sort of update from the server. This appears to be some sort of observer pattern. I was just wondering if this pattern was documented somewhere. 回答1: The technique is actually called Long Polling. This is one of the popular

问题 I wrote an aricle a couple months agoMY POST but I want to make some changes to I. Now all my code is worked out in the Swingworker class. But I want to use the MVC methode and use the observer pattern to update my variables in the view. Now i have something like this public class CopyFrame extends JFrame { private JTextarea textArea; private JProgresbar progresbar; public CopyFrame(){ progresbar = new JProgresbar textArea = new JTextarea(); progresbar.setMaximum(100)); /*in this method I

问题 lets say i have classA which is a class of audio,that sample the audio input many times. each time class A get a new data (can happen many times in second), he needs to inform another class, which is classB . Now, i could just make an instance of class B in classA and call B when there is a new data arrived, but this is not a modular software. i want classA to be "blind" to the outside, and just to add him to every project, and to have another classB that will register him some how, so when A