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Questions tagged [singleton]

The singleton is a design pattern to ensure that exactly one application-wide instance of a particular class exists.

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1answer
54 views

Managing a collection of object instances and getting them back out with instance manager / service locator

I'm creating an event loop for an asynchronous event execution library for PHP in PHP. Note that this is for a library and not an application. My event loop is just that -- a simple event loop that ...
3
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1answer
168 views

Execute startup method asynchronously

The goal is to call startManager on application start so that the manager is initialized in background without blocking application main thread. Is it a safe ...
12
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1answer
128 views

Storing messages for the application's runtime

I am currently writing a well.. manual testing site for a chat-based bot. The full code can be found on github. For that purpose I had to keep track of the messages currently in the "system". The ...
3
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1answer
443 views

Blocking builder with singleton

I am trying to implement a singleton builder that would be shared across multiple builder threads for Coordinate objects. Here is the simplified target class ...
3
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1answer
782 views

Ensure only a single instance of static template class member

I am interacting with a C library, whose documentation states that certain functions are not thread safe. Since its functions deal heterogeneously with multiple types, I have written a template ...
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0answers
160 views

Singleton request validator and sanitizor class

I have tried to code a PHP singleton class for validating multiple/single fields (sanitizing is optional). When validating single field, on success it will return 1 (...
6
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2answers
2k views

Thread-safe Phoenix Singleton class template with Boost

I've implemented the phoenix-singleton as a class template with boost inspired by Modern C++ Design. The code compiles fine with MSVC 2013 - and it seems to work, but I'm new to multi-threaded ...
9
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1answer
9k views

Can we now `implement Singleton` using Java 8?

After my success with extending enum - I thought I would try to make Singleton creation as simple as possible since Java-8 makes ...
2
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2answers
2k views

Proper way to wait end of a service and singleton design

My code works fine and I would like to know if I chose the best strategy to implement my code, or if It can written better (more fast, more clear, best use of design pattern, etc). In my android ...
3
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1answer
393 views

Lazy singleton with BackboneJS

I am trying to have a Backbone.Model which is a singleton and I wish to instantiate it lazily. I only need to support modern browsers so please do not worry about the use of ES5 getter. Is this the ...
12
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5answers
11k views

Singleton Database class

Currently my team is building an application involving a database. We have to write a lot of data (approx 2,000,000 records) to the database and therefore we decided to open a connection once and ...
8
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3answers
964 views

Singleton Database wrapper

Before everybody yells at me about why I wrote a PDO wrapper class, it's to avoid writing try/catch, ...
3
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2answers
4k views

Correct way to implement a Singleton field

I have a helper class that does HTTP operations on Android. Every method uses a client field. I think it's a good idea to make this client a singleton since every method in the class uses it. The ...
4
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2answers
2k views

Necessary singleton in DAO

I am using a singleton in my DAO. Would I be better off with static methods? Also, should I be worried about synchronization of the singleton and my data structures?...
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2answers
219 views

Address book with singletons

My main goal with this refactor was to change instance methods that should have been class methods in the first place into class methods. My secondary goal was to add singletons to these classes ...
4
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2answers
83 views

Static variable representing program state accessed with multiple functions

I have this method that performs certain functions based on the state that the algorithm is currently at: ...
2
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2answers
3k views

PHP Trait Singleton

An implementation of the singleton pattern in PHP using a trait (added in 5.4). Is there anything missing, any ways to create a second copy of the class? ...
6
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1answer
3k views

Searching for songs on an Android application

In my application I need to search for some songs on my external storage card every now and then. On startup I read everything, however when it comes to new activities I thought I could just pass the ...
5
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2answers
2k views

Android global data

I have a huge list of song objects in my program and I need those objects in almost all activities. Well, at least a part of it up to everything. So I created a class which looks pretty much like ...
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3answers
2k views

Is this good design for custom email template?

I read effective Java by Joshua Bloch. And it said use enums over int constant. So I was thinking instead of using hard coded strings I could also use enums. The forgotpassword.txt and confirmation....
6
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1answer
156 views

Manage a collection of settings in memory with global scope

I have a WPF app and a bunch of read/write settings that need to be accessible from various view models. a setting can be any type (string, ...
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1answer
156 views

Singleton-like pattern for a project [closed]

I'm changing the inner implementation of a project. In order to do so, I've created an interface that will be implemented in 2 different ways. One of this ways is by class ...
9
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4answers
5k views

Sound manager for Android

I created a singleton class for managing sound effects on Android. This class will only be instanced and loaded once at the beginning, and each activity will use the loaded songs. I don't know either ...
4
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1answer
644 views

Singleton With Sub-Singletons

I've found myself wanting an easy way to implement chat into various apps, so I developed a set of classes for the firebase.com backend that make it easy for me to quickly set up the nuts and bolts of ...
6
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2answers
736 views

Singleton design pattern

I am a beginner in PHP-OOP and design patterns. I have got this basic piece of code in Singleton Pattern and I changed it in order to understand its behavior. I can see that it works as expected. ...
6
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1answer
491 views

A parametrized Config singleton

Here is an attempt to code a specific kind of Singleton - the one geared for our configuration needs. It needs to be initialized with a configuration location, do not allow copies or other instances, ...
4
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1answer
2k views

ResourceManager Singleton

As I understand creating lots of resource managers in C# may be a bad idea so I thought that the best thing to do would be to create a singleton for this. However, I'm not 100% if this is a good idea,...
6
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2answers
3k views

Simple Java Singleton

Below is a Singleton that I designed as a piece of sample code for a website I'm working on for fun. The goal is to use the Singleton to hold an Earth object since ...
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2answers
5k views

Using a singleton class to get and set program wide settings

The following code works and does what I want, but I'd like to confirm I'm using this OOP concept correctly. I'm using the following class to get and set some configuration parameters for my program. ...
3
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1answer
116 views

How do I avoid explicit type switching when operation based on state?

I've encountered a problem that I have to solve using dynamic_cast to invoke different functions, depending on the type of class State family. I was re-factoring a ...
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1answer
3k views

OOP MySQLi singleton

I'm starting with object oriented programming, but I know PHP procedural style "pretty well" I'd say. I'm working on a ticket support site for this website. This ...
6
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4answers
2k views

Singleton SpinLock: Making Random Thread-Safe

Is this a valid and safe use of .NET's System.Threading.SpinLock? Why am I doing this? Random's public methods are not ...
0
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1answer
479 views

Creating a singleton container class for intrer-class messaging

My question is for validation of my code (any loop holes / bugs) and guidance the best methodology to implement for my requirement. I am developing a Python application that will have many classes. ...
2
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2answers
925 views

I need code review on using singleton to access local database

As I get to some performance issues in my app and find that I use database access in a bad way. So I decided to move to singleton pattern. I need someone to review this code and confirm me that I made ...
2
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1answer
229 views

Singleton has logic and state, and logic has state

------edit--------- note: this is for a MUD client, so the commands are issued to the MUD game server -----end edit-------- For an overview, here's the structure of the project: ...
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1answer
5k views

PDO class for multiple databases

I have a PDO class below: ...
2
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3answers
2k views
17
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3answers
43k views

Singleton using enum

Is this the correct implementation of a singleton using enum? ...
3
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4answers
6k views

Global data singleton

I need a global data in my application. My application uses several threads to access and add items to my global variable. The global variable is a ...
7
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1answer
459 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. ...
3
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2answers
5k views

Singleton interface in Java

I've created a singleton by means of an interface. I don't want to make a thing with getInstance() etc because I don't care about inheritance, and it's redundant ...
2
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1answer
1k views

Abstract class which uses a abstract factory -> New implementation with Singleton

I have a abstract class which is extended by many many other classes: What I have done: ...
1
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1answer
718 views

Mixin both instance and class methods in Ruby

I have a Ruby class into which I want to include both class and instance methods. Following the pattern described in "Ruby Pattern: Extend through Include", I'm currently using the following: ...
27
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1answer
24k views

Single-instance WPF application

This is the code I implemented so far to create a single instance WPF application: ...
1
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1answer
348 views

PHP my way of threating static classes

A few days ago I've faced an annoying problem. Let's imagine we have 3 classes: Base, System, Handler. The classes Systen and Handler both inherit from the class Base. I want to access those classes ...
2
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2answers
788 views

Objective-C singleton implementation

Is this the right way to do a singleton in Objective-C (coming from an Android background, with a little understanding of threading)? ...
3
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2answers
293 views

Objective-C retain / release snippet

Here are some snippets I coded and I would like some feedback on my way of handling this: I have a utility class, as a singleton, that provides me with a method named ...
9
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4answers
20k views

Threadsafe DBContext in singleton

I found out the hardway that access to DbContext in .NET is not threadsafe. I have a singleton for logging things using a dbcontext. The original version uses something like ...
2
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1answer
724 views

Singleton Boost-based timer

I would like a review on this code, and how I could make it better. ...
7
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2answers
3k views

C++ shared_singleton

I actually feel bad posting "yet another singleton"... I wrote the following one many years ago and had recently found another application for it. We had many threads, each running the same function ...