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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Singleton implementation of a database connection
I have implemented as follows, a class applying singleton pattern to get a global single access to database.
I intend to provide a thread-safe implementation.
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Classes to help transform "How hard is it to …?" questions into replies like "It's really hard to …"
I've written a Twitter bot, @answering_yelp, which responds to another Twitter bot, @hard_to_yelp. They scrape yelp reviews for sentences which start "How hard is it to..." and my bot answer with some ...
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C++ singleton using templates
Is this a good Singleton implementation? Is there anything I should be aware of? If so, how can it be improved?
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Singletons with eager and lazy instantiation
I've found more than one implementation of the Singleton Pattern in Java (more like 5-6). I want to know if both of the following snippets of code (written by me) are valid implementations of ...
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An improved single instancing library
I previously posted a question: Single instancing class and received some good feedback on it.
I have implemented most of the changes suggested by @EBrown.
I also implemented the suggestion by @...
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PHP Singletons Wrapper (Dynamic Admin) [closed]
I need to create an administration board that allows devs to create or modify options and display them in a panel. The Admin needs to be the same on each call made to it.
I've chosen to make all ...
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Log4j Singleton
I'm trying to design and develop a singleton class that will handle resolution and configuration of log4j (not log4j2). The basic idea is to have a single class, reusable in any application, that ...
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Monitoring errors with singleton
I need to monitor my functions for "errors" and want to print the warnings at the end of the functions. I thought using singleton class could be a good idea in here (code inspired by this example):
<...
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Is this a good and simple example for Singleton Pattern [closed]
This is a scenario where we keep a single instance(as in Singleton Pattern) to get the configuration of an application.
Below is the main class and i set values to the configuarion values here and ...
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Caching all the prepared statements in thread safe way
I have a below Singleton class where in my getStatement method, I populate a CHM by doing if check.
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Singleton Pattern + unavoidable Public Constructor
We have an object that needs to be converted to a different type before storing it in database. For that purpose, the library provides an annotation over the field that specifies the appropriate class[...
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Unit-testing friendly singleton
In my project we have a few singletons, which tends to be problematic in unit tests. So I wanted to find solution for the problem. Here is what I came with so far:
smart_singleton.h
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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 ...
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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 ...
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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 ...
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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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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:
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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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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 ...
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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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(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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Configurations and interrupt handler for a microcontroller using a singleton as a static instance
In my project I need to have one class as singleton which must be globally accessible:
board.h:
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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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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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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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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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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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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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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 ...
