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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Header only c++ singleton pattern implementation

I want to implement the singleton pattern in a header only c++ library. (Please refrain from sharing your opinion on the pattern itself!) This would be trivial if I could rely on the compiler ...
4
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1answer
200 views

JSON loader with event bus, cache, and session

I have an Android application which needs to retrieve JSON files from a server and then display the information in my app. To accomplish this I have the following architecture: The main activity adds ...
3
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3answers
2k views

Base class for singletons

Even though singletons are bad practice and often unnecessary, I still see many developers using this pattern over and over. Since implementation of this pattern usually requires some common code, I ...
1
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1answer
248 views

Singleton Provider

I've taken over a code base that is still very much in it's infancy, and stumbled across this class. I'm just wondering if it's actually worth it to have a ...
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1answer
54 views

How can I extract these similar codes into only one method? [closed]

I have implemented three ways of Singleton idiom in Java, and now I want to write some test code to see there performance. Here is my code: ...
3
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1answer
280 views

Storing global constants in app delegate or singleton

I am converting a non ARC projecs to ARC. I just found that after login in my old app, the data is stored in app delegate objects, like Home_DataArray, various ...
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1answer
712 views

Generic Singleton (Thread Safe)

LifeTracker.h ...
2
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0answers
50 views

Java interface to C library - Refactoring to singleton usage

I am currently writing a Java interface to a C library. It mostly just delegates calls and adds a object oriented layer on top of it to make integration into a regular Java program more natural. The ...
4
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4answers
246 views

Client to connect to server and show a text menu

First of all: Sorry for my English, that said... I am developing an obligatory for my University, so far it has a class that provides the user with options to connect to a server (once connected it ...
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2answers
2k views
2
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3answers
522 views

Settings class in C# application

I made a settings class for my own C# application. My main goal was to reach this class from every other class (this is why I choose the Singleton pattern). I also wanted to distinguish the different ...
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0answers
102 views

JavaScript Singleton Pattern/Class “Methods”

I have a library that will be called in multiple places. Here is my implementation: var vessel1 = new Vessel(); var vessel2 = new Vessel(); ...
0
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1answer
63 views

Generalizing the Initialization of Singleton Derived Classes

I have the following construct for storing and restoring my applications settings to and from XML. ...
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1answer
76 views

Does this work for Singleton Class concept? Trying to fill older HashTable once on login [closed]

I am trying to fill a hashtable with LicenseID and FullName when user first logs in. I don't have access to the Licenses database right now. So "Context" is a place holder. I am at loss if what I am ...
3
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1answer
444 views

Composite implementation of a prototype singleton registry

I am studying design patterns and I've implemented a composite prototype pattern which is also a singleton (one instance per JVM). The main and most important part of the code is the ...
2
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2answers
112 views

ResourceManager class consisting of multiple singletons

I've implemented a class, which provides access to different static resources, which are used by different frontends. I'm hesitating, because in Java getters and setters are quite wide spread. So my ...
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1answer
2k views

Singleton manager/service classes with mockable dependencies in swift

In our swift project, there are multiple service classes that encapsulate functions, mostly network-api calls. They implement a protocol, and depend on other service classes, e.g. an authorization ...
2
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1answer
2k views

Singleton method for Redis connection in Python

Here's my class for providing a singleton instance of a Redis connection. What do you think? ...
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0answers
165 views

Using a singleton for a collection of discounts to calculate?

I'm wondering if using a Singleton for a storage of discounts is the right way to go. This is because I will be looping over all added discounts in another class. client code ...
3
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2answers
12k views

Simple singleton database connection pool

I'm studying design patterns, and to demonstrate a singleton, I've implemented a primitive database connection pool. ConnectionPool.java ...
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0answers
772 views

JavaScript to connect to Redis using Singleton

I'm trying to create a class to connect to Redis in Express. I don't think my code is good enough as I got variable db hanging out. ...
1
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2answers
740 views

Initialization lock for singleton

I'd like someone to double-check my use of Atomic primitives, because multi-threading is hard. What I don't want to do is locking the whole get method, or having too many pre-checks per get() call. <...
1
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1answer
820 views

Throwing exception in the singleton pattern in C#

I'm implementing an HTTP client shell that's going to be used for the lifetime of my application in C#. It needs to be initialized before the instance can be accessed. It looks something like this: ...
2
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1answer
582 views

Singleton implementation of Cache Dependency Manager

I am trying to implement a singleton CacheDependencyManager, by combining this CacheDependencyManager from Steve Greatrex with a singleton pattern from Jon Skeet (example 6). I'd really appreciate ...
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0answers
188 views

JavaScript sound manager (singleton / static object using observer pattern)

I have some JavaScript code i would like your feedback on please. My goals: SoundManager should be a singleton/static class that has one instance. ...
1
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0answers
262 views

Claims authorization service usage

I'm doing an AuthorizationService. I'm not sure how to do the usage interface of this service, so that it's practical and handy. It doesn't necessarily has to be an ...
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1answer
360 views

Enum Singleton implementation in Java

I just wanted to implement the enum singleton in java. Here is my implementation where I have tried to create a singleton DataSource instance: ...
6
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1answer
729 views

Generic singleton array with archiving and insertion functions

I find that I often have to maintain a singleton primarily to hold an array that is sometimes persisted between user sessions, that should have only one class of items, and that sometimes needs to be ...
3
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1answer
283 views

Singleton Class for WordPress Plugin

I'm developing a WordPress plugin using the singleton pattern with the following requirements: There should ever exist one instance of the plugin Another instance of the object should never be ...
5
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3answers
808 views

Loading Configurations from plist into singleton

In my iOS application, I've created a singleton class that reads a configuration plist file and provides accessor methods to easily retrieve the values: ...
3
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0answers
176 views

Threadsafe singleton factory to use in Apache thrift server RPC system

My goal was to write a factory that the code did not have to be edited. Thus I am registering my factory functions into a singleton factory. I am going to be using this code in Apache thrift server ...
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1answer
78 views

Application Configuration in PHP

I'm learning PHP and I know too many ways to configure the application. I use this method: Folder: app config app.php db.php src class.php index.php ...
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1answer
248 views

(Y.E.S.E.J.) Yet Another Singleton with Enum in Java

I have a Java class which has to be generated only once for all the objects that I have - it is a small program. This singleton class holds a mapping of characters. I Googled stack overflow and found ...
6
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1answer
134 views

Android app with config and customization classes

I have an Android app with three different Activity classes. Each of the Activities uses and changes config and user-customization data stored in a wrapped ...
6
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2answers
564 views

Singleton-ish RMI Server

In this program there is a single remote server which performs miscellaneous work. Because there is only one server, it seems like a singleton pattern could fit well. The problem that a distributed ...
6
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1answer
97 views

Creating an in-memory ViewCounter that commits to database every 10 minutes

This singleton is responsible for counting every pageview (called Routes in our case) we get by id, until the timer runs out and commits the results to the database in one query. Then the counter gets ...
2
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1answer
634 views

Global.asax singleton

Please help me decide whether this should be good or bad idea to declare a Singleton variable in Global.asax file. (It is not actually singleton pattern, I just want to make sure that only one ...
3
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1answer
2k views

Singleton base class

I just wrote a singleton base class for a hobby project I'm currently working on. Python is not my first language, which is why I am not sure if everything is done the pythonic way. I also used ...
3
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2answers
2k views

Manage Sessions within a Singleton

I am looking for advice if the below code is a good idea or not. If not, why? I am building a website which allows a user to purchase items. The user account and cart items will be stored in Session. ...
2
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1answer
66 views

Javascript singleton to notify different objects of changes in viewport size

I'm working on a singleton object to manage size changes in the viewport, I wanted it to be a singleton because there may be different unrelated objects that need to be notified when a change in ...
2
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1answer
64 views

Persisting data between HttpRequests in MVC

IMetadata ...
6
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2answers
233 views

Building in the built-in declarations

In order for Rubberduck to be able to "recognize" the built-in VBA functions, procedures and objects, I added yet another constructor parameter to my Declaration ...
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1answer
2k views

Dependency injection thread safety

Is it OK to mix different lifetime of ISerializer and ICacheProvider in this case? I am using Unity DI. In this case, whenever <...
0
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1answer
728 views

Ruby singleton for logging

I currently have a logging setup that looks like this: ...
0
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1answer
10k views

A Singleton Base and derived class

I have a base and derived class since I need to have different kinds of concrete classes. I cannot use the getInstance() function in the base class since I cannot ...
3
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1answer
457 views

Reducing lock contention for a caching utility, or make it totally lockless but threadsafe

My Java program is a module called configProxy which fetches configuration entries from a remote node (say from a Redis instance). When the caller calls the ...
37
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4answers
30k views

Swift 1.2 Singleton Implementation

I am pretty new to Swift, as a solo developer I was wondering if somebody could pass comments on the singleton implementation below. The code does work, but being new to Swift and knowing that there ...
4
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1answer
184 views

Correct usage for singleton and reusability?

I've made the following DataSetReader, DS Attribute, and DataSetManager. My main concerns ...
5
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3answers
5k views

Design of a remoteControl class for connecting to electronic devices

In a course that I'm taking on learning object oriented programming in java, I have completed an assignment for modeling a home entertainment system and the ability for a user to be able to use a ...
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1answer
270 views

PHP framework building: initializer and object loader classes

I am building a PHP framework and would like to get some feedback on a few different sections of the project. I consider myself still a neophyte in PHP so I would like to ask if I'm going about ...