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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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 (...
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Dependency problem with field changes
The Observer Pattern is used here to notify changes in a Person's data. For example, when age changes, the value of can_vote() ...
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Generic observable type
I am writing an observer design pattern that is not too complex but I still feel there's a lot for me to learn about C++ be it little details (especially coming from C).
A couple of observations:
I ...
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JS stopwatch using 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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PyGame Event Handling
I'm new to pygame and tried to write my own Event Manager because I couldn't find a solution I was satisfied with. So I wrote my own inspired by the observer pattern:
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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 ...
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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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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 ...
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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 ...
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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 ...
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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 ...
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Android BMI calculator using LiveData
I have made a Body mass index-calculator using ViewModel and LiveData.
Source-code of the MainActivity:
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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 ...
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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 ...
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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 ...
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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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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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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 to ...
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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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Observable Object Proxy
As a part of my (future) MVVM framework, I need to be able to detect changes on an object. To do this, I used the RealProxy, a C# object that implements Aspect ...
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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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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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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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Message bus in C#
I wrote a MessageBus class whose only purpose is to deliver messages from object to object without direct link between them.
I encountered a problem with duplicate ...
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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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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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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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The Observer design pattern in Python, with unit tests
I'm continuing to work on the Head First Design Patterns book in an effort to become a more efficient and better Python programmer. Code review for the Strategy pattern in Chapter 1 is here with ...
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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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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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2D board game: good Model part?
First time writing a big project in OOP. I am quite used to scientific programming but not to OOP, and even less to building GUIs. I am writing a 2D board game: the player can move on a map from tile ...
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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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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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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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Custom Implementation of ObservableDictionary
I recently found myself in need of an IDictionary<TKey,TValue> implementation that was observable from a WPF UI. Since the .Net framework does not provide ...
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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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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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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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