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

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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(); ...
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35 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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44 views

Data structure of in-memory database [closed]

I am learning OOP, SOLID principles and design patterns. I have designed data structure of in-memory database in C#. Please provide suggestions to improve it better considering solid principles, OOP ...
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60 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 ...
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43 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 ...
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2answers
80 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
41 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 ...
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1answer
49 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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162 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 ...
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2answers
103 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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56 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. ...
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2answers
32 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. <...
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1answer
87 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: ...
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1answer
80 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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60 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. ...
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1answer
74 views

Singleton Service Initialization [closed]

Is it ok to have a Singleton Service with Initialization like this? ...
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65 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
80 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: ...
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60 views

Ingest data from an RDBMS to Hadoop Hive database using Sqoop

Context: The below code will run a series of steps in an ETL workflow. I would like the code to be reviewed to avoid memory bottlenecks and null pointer exceptions etc. UseCase: Ingest the data from ...
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1answer
152 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 ...
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1answer
98 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 ...
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3answers
156 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: ...
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50 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
53 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
101 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 ...
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1answer
100 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 ...
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194 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 ...
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1answer
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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 ...
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1answer
162 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 ...
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1answer
235 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 ...
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2answers
385 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. ...
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1answer
40 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 ...
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1answer
52 views

Persisting data between HttpRequests in MVC

IMetadata ...
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2answers
209 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
224 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 <...
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208 views

Ruby singleton for logging

I currently have a logging setup that looks like this: ...
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1answer
2k 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 ...
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1answer
151 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 ...
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4answers
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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 ...
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1answer
155 views

Correct usage for singleton and reusability?

I've made the following DataSetReader, DS Attribute, and DataSetManager. My main concerns ...
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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
202 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 ...
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1answer
47 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 ...
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1answer
110 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 ...
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1answer
120 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 ...
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1answer
189 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 ...
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1answer
276 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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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 (...
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2answers
750 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 ...