Questions tagged [callback]

Callback is facility to save a piece of code so that it may be invoked later in the current environment (Typically in response to an event)

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41 votes
3 answers
42k views

Partitioning an array based on a condition in Javascript

Using the array.filter function, I can efficiently pull out all elements that do or do not meet a condition: ...
Max Rosett's user avatar
36 votes
2 answers
6k views

Asynchronous network callback code

I did not get the job after submitting this piece of work in an interview, but I have no feedback to know what "BAD" things are inside this block of code. The requirements are: Connect to the ...
TheOneTeam's user avatar
21 votes
2 answers
15k views

C++ Observer design pattern implementation

I'm using the Observer design pattern in order to manage events in the game I'm currently developing. I based myself on the implementation demonstrated here but improved it in order to ease its use. ...
AntoineB's user avatar
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13 votes
2 answers
5k views

Implementation of a Thread Pool in C++

I wanted to implement a thread pool to test my knowledge of various modern C++ features. The end result could be better, but I need a review as I'm not sure about delicate things especially regarding ...
KeyC0de's user avatar
  • 233
12 votes
1 answer
485 views

Pledge: Promise-like entities design goals experiment

Background I was writing a promises/a+ implementation, just for fun. About halfway through I decided it wasn't that fun after all, so I decided to do something a little different. Thinking of ...
Dagg's user avatar
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11 votes
1 answer
2k views

C++14 Event System

I've created a simplified event system for C++14. The code is commented, so it shouldn't be hard to read. There's also a simple usage scenario below. It is still a work in progress and uses some not-...
Crossfire's user avatar
  • 211
11 votes
1 answer
2k views

Callback in Linux kernel driver in order to hide device's low-level protocol

I'm am writing a Linux kernel driver for HD44780 LCDs connected via I2C bus. In my last change I tried to decouple low-level code (which talks to the device via I2C) from device's logic (printing ...
m.g.'s user avatar
  • 111
10 votes
2 answers
6k views

C-ifying a capturing lambda

What do you think of this code? ...
user1095108's user avatar
  • 1,414
10 votes
1 answer
690 views

ActivityLifecycleHelper implementation

Description The ActivityLifecycleHelper uses wrap(Context)to create the class and save a global ...
Jon Merritt's user avatar
9 votes
4 answers
950 views

ViewModels Mediator with multiple generic callbacks

I'm developing a mediator for an MVVM application. This application lets employees file tickets with IT support to ask for help. The mediator communicates messages and triggers callbacks between ...
Queder's user avatar
  • 255
9 votes
1 answer
4k views

Simple callback wrapper for an embedded C++ app

I'm writing a callback wrapper class for an embedded application in C++11. The basic idea of the class is to be able to use it as a replacement instead of C-style callback functions, with the added ...
Venemo's user avatar
  • 243
8 votes
2 answers
440 views

Concurrent Task Waiter 2

This is an iteration of my previous question: Concurrent Task Waiter Summary from before: I have some code designed to simplify managing multiple asynchronous operations. The code creates ...
Nick Udell's user avatar
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7 votes
4 answers
436 views

Identify Java Callback

I have this common design in my application: ...
Pierre-Jean's user avatar
7 votes
1 answer
244 views

Do nothing lamda...

$privilegeStrings = array_filter($privileges, function ($s) { return is_string($s); } ); Is there a better way to specify that I want just the string values in ...
Billy ONeal's user avatar
  • 1,470
7 votes
2 answers
22k views

Callback on AlertDialog

I am using an AlertDialog in Android, asking the user for some input. I would like do run some code when the user has finished entering her input. Since an ...
JonasVautherin's user avatar
7 votes
3 answers
2k views

C++ Generic Callback class with removable listeners by unique id

I'm quite new to the STL. Does this make sense? Is there a better way of removing the listeners instead of using shared_ptr while keeping the code short and simple? Is there something in the STL to ...
fededevi's user avatar
  • 310
7 votes
1 answer
1k views

Simple helper for making things "disposable"

I often write small classes to make undisposable things disposable so that .NET can handle something automatically, like stopwatches or logs. I thought why not write a small helper that can be used ...
t3chb0t's user avatar
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7 votes
1 answer
473 views

TFunction: std::function replacement for event system

I've been trying to implement delegate for my event system. I thought that maybe std::function can do the trick for me, but it turned out to be not comparable, so what i have end up doing is this - ...
Lex's user avatar
  • 71
7 votes
1 answer
132 views

Requesting Resources Until Exhaustion

When an API has a 'next' feature, I use the following pattern to obtain all the results: ...
Tanaki's user avatar
  • 173
7 votes
1 answer
502 views

Prime Numbers Store

Let's say we need to create a store for selling prime numbers. Users enter the store and ask to buy a number. If the number asked is a prime number, 1.1. then it's either available for sale 1.2. ...
rycle's user avatar
  • 145
7 votes
1 answer
4k views

Custom ostream for a println-like function

I am writing a plugin in C++ that uses C API that gives me a single logging function with this signature: typedef void(*println_t)(const char* text); I want to ...
IS4's user avatar
  • 171
7 votes
1 answer
63 views

Apply arbitrary action during recursive generator function

I've got this recursive generator function. It will traverse an object looking for "leafs", any keys that don't point to sub-objects. Then it applies one of two actions on the leaf and yields it. Any ...
Letharion's user avatar
  • 618
6 votes
2 answers
420 views

c++ multithreaded message broadcaster with link lifetime management v3

note: This is v3 of code that was previously reviewed. I have written a class that handles listeners registering callbacks to receive messages. Link lifetime is managed (or is it? See below). Code is ...
Diederick C. Niehorster's user avatar
6 votes
1 answer
150 views

C# asynchronous notification vector

The purpose of this class is to efficiently notify another thread when data is available with minimal blocking to access/pass the data. The data reader/producer thread processes data in bulk which ...
sfanjoy's user avatar
  • 233
6 votes
1 answer
6k views

Node.js callback error pattern

The errors are passed through every callback, but in fact, it might be better to throw an error at higher levels. For example, look at the mongodb.js database function. It passes through an error in ...
onlineracoon's user avatar
6 votes
1 answer
3k views

Simple implementation of signals and slots mechanism using templates

I tried to implement a simple signal&slots mechanism for some DSP software that runs on embedded Linux. I would like if somebody can review this code and give me some guidelines. Any review and ...
Nenad's user avatar
  • 63
6 votes
2 answers
72 views

Alternate way for comparison call back function?

I'm doing a programming practice problem and was wondering if someone can suggest a better to create/setup the call back for the comparison function. I have the following classes: ...
user3379755's user avatar
6 votes
2 answers
210 views

Is this the right way to work with callbacks and the EventEmitter?

I'm creating a small online multiplayer game in NodeJS and I'm wondering if I'm "doing it right". Here is a bit of my code: ...
Martijn Buurman's user avatar
6 votes
1 answer
163 views

replaceWithCallback() UDF

As explained in my blog article… I was looking up the docs for Javascript's String replace() function the other day (because, no, I could not remember the vagaries of its syntax!). And whilst ...
Adam Cameron's user avatar
6 votes
2 answers
544 views

Error Code Stack Trace and Propagation Library in C

I've been programming in Go and I enjoy how easy it is to create descriptive errors and propagate them up the call stack. I wanted that sort of ease and consistency in C so I created a small error ...
Ollie's user avatar
  • 163
6 votes
1 answer
831 views

Python model for a "snake"-like game

I wrote a python model for the game "snake" that I'm not really satisfied with. My intention was to separate the game logic from the drawing and input handling (which worked quite well) but I've got ...
tfeldmann's user avatar
  • 163
6 votes
1 answer
220 views

Processing input in background while user is typing

Use case A GUI with 2 controls: An input control for text (a DNA sequence) that should be analyzed A result control that displays the analyzing result of the entered text The analysis takes 2-3 ...
JanDotNet's user avatar
  • 8,538
6 votes
1 answer
3k views

Callback functions to select the tab to the left in Google Chrome

I'm a JavaScript rookie, but I wrote a JavaScript function as part of a Chrome extension that will activate the tab to the left of the currently active tab. The function is pretty ugly, but I couldn't ...
GregB's user avatar
  • 163
6 votes
1 answer
2k views

Hooking with Python3 Decorators

I wrote this prototype after reading the Wikipedia article on hooking. I didn't bother to read any of the code examples listed there because, well, I just didn't. I don't have a good excuse. The ...
user avatar
6 votes
1 answer
1k views

Request and callback design

I am just trying to improve my coding and designing skills in C++ and for that I am trying to solve same age old problem of mapping a http request to method. Could you guys please look at my program ...
Neeraj Kumar's user avatar
6 votes
1 answer
239 views

Rate limiting function calls

I wanted to write a function that when applied to another would rate limit it, but permit all calls to eventually make it through. Comments and criticism welcome. ...
52d6c6af's user avatar
  • 672
6 votes
1 answer
1k views

MVC Model validation callback

I have made a simple MVC framework of my own for my personal website to learn a thing or two about how this whole thing even works. I think I've got the idea, but there's one thing I'm not sure about. ...
user2374794's user avatar
5 votes
2 answers
325 views

Message Broadcaster

I've written a basic event messenger broadcasting service. This is meant to allow for broadcasting events between loosely coupled areas of code where you may not have or care about a direct reference ...
M2tM's user avatar
  • 146
5 votes
2 answers
3k views

Synchronization in an event manager

I'm working on an event manager, and I am wanting it to be a tool developers use. It is lightweight and it uses annotations to register events. I've tried to set up ...
CoderMusgrove's user avatar
5 votes
2 answers
117 views

Simple replacement for Redux in ES6

The idea about this code is that it's a full replacement of Redux — in 22 lines of code. ...
Merc's user avatar
  • 557
5 votes
2 answers
158 views

Event emitter npm module

I was asked to complete the task described below: Event Emitters are objects that serve as the core building block in event-driven architectures. They simplify the process of handling asynchronous ...
Sᴀᴍ Onᴇᴌᴀ's user avatar
5 votes
2 answers
332 views

Swapping dynamically populated images on hover/touch

I'm using jQuery to swap images on hover. There's a main image, and a gallery of thumbs. When the thumb is hovered over/touched, the larger version of it populates the main image, and the smaller ...
alexwc_'s user avatar
  • 249
5 votes
1 answer
588 views

Avoiding callback chaining in authenticator

I'm developing an iOS Application in Swift that uses Google Cloud Endpoints as its backend. For now, I've just written the code for the user to login with his Gmail account and I've refactored it as ...
W.K.S's user avatar
  • 512
5 votes
1 answer
91 views

Process chain approach

I've been researching about JavaScript and jQuery function chaining and different callback techniques. I am trying to create a very generic code that allows chaining, and in a way that I may create ...
Maurício D'Angelo Fernandes's user avatar
5 votes
1 answer
95 views

Function to foreach over an array

I made a very simple generic function to foreach over an array in C using a callback function: ...
PointerToConstantChar's user avatar
5 votes
1 answer
65 views

Organize JavaScript for video player controls

I have a small piece of code, and the problem is that I don't know how to organize it. There are tons of tutorials about JS code organization but I feel that those are for large scale apps. Also, I'm ...
oscar539's user avatar
5 votes
1 answer
885 views

"Piping" from a callback to an Iterator

My project has a central concept of a Callback<T> which is defined very simply: ...
Steven Schlansker's user avatar
5 votes
1 answer
6k views

Remove an event listener after firing once or any number of times

Remove an event listener after firing once or any number of times This is what I have: ...
XP1's user avatar
  • 151
4 votes
2 answers
7k views

Flattening multiple nested node readline questions

Say I'm creating a simple CLI. I want to use native node readline module to take in some input from user at prompt. I thought of this: ...
sakshamsaxena's user avatar
4 votes
3 answers
6k views

Simple Publisher Subscriber in Java

I am new to Java and had some difficulty creating this simple Publisher Subscriber class. It finally seems to be working and I wanted to check if I have been following best practices and see if there ...
KNejad's user avatar
  • 171