Questions tagged [observer-pattern]

A software design pattern in which an object, called the subject, maintains a list of its dependents, called observers, and notifies them automatically of any state changes, usually by calling one of their methods.

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High-Level Managed Observers

I was thinking of adding a very high-level implementation of the event/observer pattern to my project. The implementation would manage adding and removing observers as "needed". You can use an almost ...
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Notify observers when object attributes update

I have a Singleton manager class for managing request model and its attributes. My main aim is update object observers when some of the object attributes changes. ...
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122 views

Observer Design Pattern in Golang

I am trying to practice the Observer design pattern in Golang, here is my code. I would be pleased to receive your comments, improvements, etc. ...
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1answer
66 views

Logic is stored in Components that receive input data and update output data via Observables

I have C# ASP.Net Core Webapi application that makes some calculations for physical models. I have this project class: ...
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Implementing custom observable classes

I want to implement my own custom observable class so I can have a hierarchy of components and the closest defined configuration item bubbles to the front. ...
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RXJS and Ionic- Sequencial Subscriptions Waiting on User Action

In an Ionic App a user can open a new browser via "inAppBrowser". I'm trying to get the stats of the user before they go into to the inAppBrowser, get the stats again when browser closes, and then run ...
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1answer
407 views

How to observe multiple Observables? [closed]

About the Program It's a simple implementation of Observer Pattern. The choice of different NotifyMethod will affect how those observers are notified. The ...
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83 views

Scheduler built with observables v3 (follow-up) - now testable

This is a 2nd follow-up to my previous one about a Scheduler built with observables. Although the last one was working correctly, it was only possible to see this ...
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57 views

Applying Observer-Observable pattern to a code and multithreading

I have to: 1) Apply the Observer-Observable pattern to the original code. 2) starting from the original code, I have to suppose that the modification of the array fields (slot machine numbers) ...
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Observer(Event) system (Signals and Slots), type and template based

Signals are represented as types. You can connect a member function of some instance to the Observer system. This connected function will be called whenever a signal of a type that is the same type as ...
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1answer
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Threadsafe oneshot-event which fires on subscription if the event was fired in the past

Assumptions Basically, a Connection class has a "Disconnect" event. Subscribing to this event isn't thread-safe, because the disconnection may fire from another thread right before I subscribe. So ...
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1answer
68 views

Apply stock quote changes using observer pattern

I am implementing observer pattern(refering codeproject) for stock quote update. I have created an interface for Subject and Observer. I have created instances for Subject and Observer and also the ...
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1answer
182 views

Implementing the observer pattern for a stock exchange scenario

I am trying to implement the observer pattern for a stock exchange scenario. Multiple stocks can be registered at a stock exchange. There will be stock observers who are observing some specific stocks....
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1answer
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News reading application version 2

following the answer I got from t3chb0t last time News-reading application using the Observer pattern and also following the example here https://msdn.microsoft.com/en-us/library/dd990377(v=vs.110)....
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1answer
1k views

Simple event dispatcher

Here is my very first event dispatcher. I would like to get both, style and code review, as well as some ideas to improve this implementation (new features etc.) I tried to write code in C++17 style ...
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1answer
362 views

Angular service for fetching and passing data with observables

I have an Angular service consisting of three methods: This method makes a call to my server to get a URL ...
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2answers
263 views

Make an Array Reactive (Observable)

I have written a simple JavaScript function to make an array reactive (i.e. observable). Is there anything I could improve? What the code does is take an array, a callback and a ...
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1answer
62 views

JavaScript and RxJS Password Strength Indicator

This is my first time using RxJS (or any observable library). It seems to work okay but I'm not sure about best practices. The thing that I am most unsure about is subscribing to the observable ...
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1answer
113 views

Scheduling using System.IObservable 2.0

As a follow up to this first attempt to create and use my own IObservable<T> implementation, this is version 2.0. The goal has been to correct the code where ...
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1answer
128 views

Scheduling using System.IObservable

With great inspiration from t3chb0ts ongoing work about scheduling, cron jobs etc. (last post here), I decided to make my own version of the Scheduler - using the observer pattern - as a learning ...
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159 views

Scheduler built with observables v2 (follow-up)

It would probably be too easy if the old Scheduler worked as intended being that simple. But an eye-openig review showed that from time to time it'll miss one ...
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2answers
664 views

Scheduler built with observables

I sometimes have to schedule some tasks and wanted to have my own reusable scheduler. Since I like the Rx, I build it on top of it. Follow-up There is a newer version of the ...
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1answer
3k views

Java Pub Sub implementation using broker

I have developed a simple pubsub event subscription in java. Something similar to this thread Simple Pub-Sub Event Emitter These are the goals. Class should be able to "listen" to events happening ...
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39 views

Fetching student and teacher data from a given date range

I have two APIs which fetch data of teachers and students from a given date range. I am using forkJoin to get both APIresponse and display the data with a regular interval of 10 ms. This is working ...
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2answers
70 views

JavaScript library to notify watchers of changes

Background Last year, while I was still entering the beginning of Immutability and Pure functions and whatnot I created a library for the community called ...
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70 views

Subscribing to multiple sources in RxJava

I have used RxJava to Observe multiple sources and then perform action depending upon values of Observables. I want to know if it can be further simplified. Goal: Complete implementation of RxJava. ...
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1answer
357 views

Implementation of observer pattern for Node.js

I wrote an implementation of observer pattern as part of my online battle Chess game: ...
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2answers
2k views

Observable implementation

I have implemented a simple Observable class. I think that there is still room for improvement. Especially the fact that I have separate array to observe results ...
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1answer
924 views

Implementation of Observable with multiple callback function signatures

I have been playing around with ways of implementing a generic class for supporting the observer pattern. I have already asked to review a basic approach here. Now I have come up with an Observable ...
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1answer
2k views

Implementation of Observer Pattern in C++14

I have written a small class for implementing the observer pattern in C++(14). I would welcome any comments, corrections criticisms and suggestions. Observable.h: ...
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Observer pattern implementation in C++11

Can this observer pattern implementation be improved? Problem: User will drive a car if pressed l --> car move left c--> move middle ,r--> move right ...
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C++ implementation of the observer design pattern

Started learning design patterns using C++. Below is an implementation of the Observer Pattern. Two abstract class templates Observer and ...
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1answer
1k views

Angular - reusing an observable for different queries

This is just a dummy example, but in my real world application I get a lot of data from the web API and I'd like to manipulate it on the client's side. So, I kind of stored the observable I get from ...
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1answer
691 views

Observable Logger

I'm experimenting with an alternative abstraction layer for logging that is build on top of the Reactive Extensions. This allows me to easily add features I need to my layer and map logs to any other ...
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2answers
935 views

Retry and CircutBreaker the reactive way

I wrote a simple utility for Retry and CircuitBreaker patterns. I implemented it by using ReactiveX because I thought it might actually be the perfect framework for it. I know that there is a project ...
3
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1answer
92 views

Store first value of http request with rxjs but keep doing httprequest

With RXJS library : I need to store values from the FIRST http request, but keep doing other http request on demand. I have done this code so far, and that is working. But I think there is a more ...
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Simple chat client and server in Java. (tried to refactor on Head First Java code example)

In the book Head First Java there was this coding example that created a very simple chat client and server. Both the server and the client consisted of just one class. I left the server code as is, ...
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139 views

Network of senders and receivers in C++

I am trying to create a Sender-Receiver Network. What do I mean under a Sender-Receiver Network. That means that there is some structure which consists of Nodes and connections between them which will ...
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2answers
869 views

Angular2/4 broadcast service using RxJS

I am no expert in RxJS as I am still learning my way around the new paradigm of Observable/Subject. I was trying to implement a broadcast service (based on NgRadio) that allows a new subscriber to ...
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2answers
85 views

Lightweight flexible observer framework using weak references

I found a need for a simple, generic publish-subscribe framework for my Java application. I looked over a few implementations on Code Review and I think mine avoids most of the pitfalls. Single-...
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135 views

F# Observable.subscribeWeakly implementation

In this SO question I needed an observable subscription function that can be used kind of like Observable.subscribe, but that does not keep a strong reference to ...
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411 views

Observable Object

I have created an observer and an observable object class. The idea being that you can create an observer that does some action whenever object being observed changes value. Design goals: Be able ...
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1answer
324 views

Merging union Observables

I am having a scenario where I need to execute observables that depends on the result of the first one. However I need to keep the result of the first observable. I couldn't find any extension that ...
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0answers
259 views

Simple C++11 Subject-Observer

Building on the answer in C++ class member callback simple examples, I've tried to put together a simple subject-observer pattern without needing to inherit a virtual Observer class. I also wanted to ...
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1answer
523 views

Observer pattern for temperature and pressure sensors

I have tried to implement the observer pattern. The code should be able to handle a variable number of observables (set compile time) and notify any number of observers/registerables. Any observable ...
11
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1answer
23k views

Angular 2 clock with RxJS Observable

I'm fairly new to Angular 2 and I started off with creating a clock for my app. I tried to stick to the official documentation tutorial. Folder structure: The CSS file is still empty and the HTML is ...
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2answers
3k views

Observer pattern using a set of observers and delegated properties

The idea is to implement the observer pattern, with a separate notification method for each observed property of the observed object. Let me start with a simplified use case: ...
3
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2answers
675 views

Reusable Implementation of the Publish-Subscribe Pattern

I've finished an implementation of what I believe the Publish-Subscribe pattern is for practice and possible use in personal projects even though this implementation is fairly similar to the Observer/...
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1answer
617 views

WPF async ObservableTaskQueue class

I'm currently working on a WPF application, making calls to various web APIs. Thus, I'm looking after a special observable tasks queue: Progress value must be available Tasks (API calls)/seconds must ...
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1answer
111 views

Removing same event from listener

I have a myDiv.mousedown, window.mousemove, and window.mouseup event. I'm trying to organize ...