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.

Filter by
Sorted by
Tagged with
1 vote
1 answer
50 views

Multithreaded observer pattern in Rust

I often want to program in an event driven way, but classic implementations of the observer pattern often pose an ownership challenge, and they only get more difficult once multiple threads are ...
user avatar
  • 303
1 vote
2 answers
59 views

Requests and handling requests

For this task, I don't think that the Observer Pattern can be used in its classic form. Those who have received the requests and those who choose to accept the request are not the same group. Those ...
user avatar
  • 1,109
1 vote
1 answer
46 views

Typescript simple observable state and web component

I've been experimenting with wiring up a vanilla web component in a reactive manner to a state box. The goal is that when something changes on the state object, the web component reacts. I realize ...
user avatar
  • 113
0 votes
0 answers
25 views

Two different JavaScript implementations of the observer pattern using class inheritance and concatenative inheritance

To practice design patterns and JavaScript, I'm implementing the observer pattern in two different ways: One implementation using class inheritance And another implementation using concatenative ...
user avatar
  • 729
4 votes
3 answers
114 views

Observer Design Pattern in C++ to model magazine subscriptions

My attempt at a observer design pattern (I know using namespace std isn't good). I'm very new to design patterns. Everything is inline with class definition. Please tell me if I'm doing anything wrong ...
user avatar
3 votes
2 answers
89 views

Generic Observer/Listener implementation in Java

I am working on a personal project in university where I am currently trying to make my own implementation of a generic observer pattern that I can use throughout my project. I would appreciate any ...
user avatar
2 votes
0 answers
68 views

Android BMI calculator using LiveData

I have made a Body mass index-calculator using ViewModel and LiveData. Source-code of the MainActivity: ...
user avatar
  • 3,758
1 vote
0 answers
48 views

Unity3D Observable Variables as ScriptableObjects

I'm trying to implement an observable pattern on variables, so that I can hook up UI components, etc. to change displayed values or other actions when their value changes. I wanted three features that ...
user avatar
  • 223
0 votes
2 answers
231 views

C++ Observer Pattern with std::function

I am/we are using the observer pattern for many things in our application. I think it's time to create a reusable base class for these situations. Most implementations I could find only do something ...
user avatar
2 votes
1 answer
138 views

Adjusting variables on change of status attribute of my Order Laravel model on the updated event in observer

I have an order model and a client model. A client has many orders, an order belongs to a single client. In the client model I keep track of how much money a client paid (...
user avatar
3 votes
1 answer
72 views

Abstract wrapper for fundamental types

I have created this interface as part of my C++ learning path. This post inspired me a lot. The idea is to use its concrete implementations to perform some actions before and after any change of the ...
user avatar
  • 31
1 vote
2 answers
295 views

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 ...
user avatar
2 votes
1 answer
85 views

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. ...
user avatar
0 votes
1 answer
42 views

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 ...
user avatar
3 votes
2 answers
397 views

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 ...
user avatar
  • 303
3 votes
0 answers
92 views

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>...
user avatar
5 votes
0 answers
109 views

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/ ...
user avatar
  • 111
2 votes
0 answers
95 views

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/...
user avatar
3 votes
0 answers
90 views

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 ...
user avatar
  • 131
1 vote
1 answer
37 views

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 ...
user avatar
  • 157
3 votes
1 answer
72 views

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 ...
user avatar
1 vote
1 answer
308 views

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. ...
user avatar
  • 121
1 vote
0 answers
292 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. ...
user avatar
  • 191
3 votes
1 answer
82 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: ...
user avatar
  • 207
3 votes
0 answers
174 views

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. ...
user avatar
1 vote
0 answers
12 views

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 ...
user avatar
  • 111
0 votes
1 answer
2k 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 ...
user avatar
3 votes
0 answers
101 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 ...
user avatar
  • 43.8k
1 vote
0 answers
249 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) ...
user avatar
  • 23
2 votes
0 answers
137 views

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 ...
user avatar
7 votes
1 answer
260 views

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 ...
user avatar
0 votes
1 answer
96 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 ...
user avatar
  • 167
3 votes
1 answer
285 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....
user avatar
5 votes
1 answer
85 views

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)....
user avatar
  • 5,329
4 votes
1 answer
2k 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 ...
user avatar
3 votes
1 answer
2k 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 ...
user avatar
4 votes
2 answers
769 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 ...
user avatar
2 votes
1 answer
77 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 ...
user avatar
5 votes
1 answer
126 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 ...
user avatar
4 votes
1 answer
145 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 ...
user avatar
7 votes
0 answers
213 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 ...
user avatar
  • 43.8k
4 votes
2 answers
1k 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 ...
user avatar
  • 43.8k
6 votes
1 answer
4k 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 ...
user avatar
  • 297
1 vote
0 answers
53 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 ...
user avatar
  • 141
1 vote
2 answers
73 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 ...
user avatar
1 vote
0 answers
89 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. ...
user avatar
  • 111
2 votes
1 answer
504 views

Implementation of observer pattern for Node.js

I wrote an implementation of observer pattern as part of my online battle Chess game: ...
user avatar
  • 255
1 vote
2 answers
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 ...
user avatar
  • 190
3 votes
1 answer
1k 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 ...
user avatar
  • 171
4 votes
1 answer
3k 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: ...
user avatar
  • 171