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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Observer pattern in Rust

A simple implementation of the Observer pattern in rust. The Observable constructor (::new) is called with a subscription function which will be called every time ...
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Pure JavaScript infinite scroll

I have a 4 list of posts. I am trying to load more posts (clones of the "original" ones) when I reach the bottom of the container. ...
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Angular observables piping

I wanted to check and see if this was as efficient as can be. The goal is to get a user's data from a group of documents that contains references to users in Firestore. ngOnInit ...
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A Python decorator for an “observable property”, that notifies observers when the data is changed

I have classes that have some data, and whenever this data changes, it should notify observers of that data change. There also should be a method to add new observers. My first approach was to use a ...
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Create IObservable<T> From Func<T>

These extensions create an IObservable<T> that creates a long running task that can be cancelled. It runs the Func<T>...
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JS Stopwatch - Is this a good way to implement the observer pattern?

I'm learning oop and also trying to learn and implement some design patterns. This question is a follow up of Stopwatch interface OOP (Vanilla JS) The app is available in https://nacho-p5.github.io/ ...
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NativeScript - Angular Service to watch iOS keyboard event listeners

I'm writing an app with NativeScript 6.4.1 and Angular version 8. There are a series of UI events in iOS that you can watch to see what the keyboard is doing: https://developer.apple.com/...
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Observer pattern over FFI

I'm trying to write up a cross-platform rust library (one, that will be used in iOS/Mac/Android dev etc.) It is based largely on concept's and code from Mozilla. One of the requirements I have is to ...
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Using generators on Observable class

I've decided to implement a simple case of the Observer pattern. I've gone about this considering you can only register 1 single observer in the Observable, instead of allowing multiple ones. I ...
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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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882 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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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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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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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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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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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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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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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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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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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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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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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 ...
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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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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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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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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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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 ...