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-6
votes
1answer
126 views

Does one really need multiple instances of a class? [closed]

Generally I'm extremely skeptical of anyone who criticizes the singleton design pattern in software. In the MVC (model-view-controller) design pattern, views and controllers are usually singletons and ...
1
vote
2answers
89 views

Passing central objects around or having global instances? [duplicate]

Having a larger WinForms application with several classes I currently pass references to several "central" objects around to function calls. This leads to more method parameters. Example: public ...
3
votes
3answers
287 views

Infinite loop with a singleton - does this type of issue have a name?

I ran into an unusual error while working on my project. To better learn from and remember it, I'd like to know if this type of error has a name or some definition. (The error itself OutOfMemoryError ...
0
votes
2answers
229 views

Java Singleton fields implementation

I have singleton in Java and I have realized, that I could make its fields static and it would work same way as regular instance fields. Would there be a performance / optimization difference? If ...
0
votes
0answers
138 views

Use a global variable, a singleton, or something else

Preface: I am working in PHP (Abandon hope all ye who enter here). Background: There exists a large set of global functions in PHP, a number of which are miscellaneous system calls, like sleep (and ...
0
votes
1answer
136 views

Singleton: Why is a global point of access bad? [duplicate]

Most people here and on StackOverflow agree that Singletons are evil. The main explanation I've come across against the use of Singletons, is they fact that they provide a global point of access to ...
1
vote
3answers
132 views

Simple Design for Singleton function in java for Kernel [closed]

I understand that Singelton helps to instantiate only one class AT A TIME. I try to learn how to Design for Singleton function in java. I want to know it better to understand Kernel. So I try to do ...
2
votes
3answers
204 views

When to use a Singleton and when to use a static class [duplicate]

I've searched about this here and on StackOverflow and found some differences between the two. But I'm still not sure in what cases one would prefer a Singleton, and in what cases one would choose to ...
2
votes
1answer
247 views

MVC design, singleton in model with initialization

I've recently learned of MVC (model view controller) and am trying to refactor an existing program. I am in a situation where I'd like to have exactly one object of a particular class so it seemed ...
0
votes
1answer
120 views

Using module level declared global “singletons” in python

Ok, I know that using singletons is generally a bad practice, but if I do it (for db connection, logging et al.) am I allowed to go (in respect of clean design) with a module defined variable that is ...
0
votes
2answers
257 views

Difference between Singleton pattern and auto_ptr<> resp. unique_ptr<>

I'm maintaining some legacy code of a physical simulation. The calculation object is build as a singleton, to ensure there is only one instance. A co-worker told me, that singleton are completely ...
12
votes
3answers
3k views

Static factory vs factory as a singleton

In some of my code, I have a static factory similar to this: public class SomeFactory { // Static class private SomeFactory() {...} public static Foo createFoo() {...} public ...
-1
votes
3answers
200 views

Is it possible to encapsulate the object itself within a dynamic property?

I ask this question out of curiosity. Lets say the class Foo is a singleton and I want to call Foo instead of Foo.Instance to access the static object. Would it be possible to encapsulate the ...
1
vote
4answers
1k views

Is it allowed to make multiple instances of a singleton class?

I am confused when I read this (regarding singleton design pattern): How do we ensure that a class has only one instance and that the instance is easily accessible? A global variable makes an ...
7
votes
2answers
324 views

How to maintain synchronised state across threads - is this a good use for a Singleton?

I hear a lot about "Singletons are always bad" around the place. I don't hate on them to that degree but I try not to use them if I have a better alternative. In this case I have a system that ...
3
votes
2answers
270 views

Application Settings, Status and more as Singleton? [duplicate]

I am relatively new to programming (1yr field experience now) and I think that I am overusing the singleton pattern and I need some input on how to do it in a better way. Right now I am using ...
5
votes
2answers
245 views

How to avoid a singleton in this example?

I have a class Image and another one ImageStore. The Image it's just a value object containing the package name and the image name. The ImageStore does all the actual work: calculates the real path of ...
4
votes
2answers
408 views

Is there a name for this design pattern? [closed]

I don't like singletons, but I have to compromise now (but only as temporary measure). However I don't want to go completely singleton. I'd rather want to use this pattern: interface ...
3
votes
3answers
376 views

Why don't we use a class and its static members to do what a singleton does?

In Java,C++,Objective C, C#, and all other similar OOP languages, Why don't we use a class with static methods and vars instead of going through a singleton syntax having to deal with various ...
5
votes
4answers
728 views

Is there something like a polymorphic Singleton?

I have a resource loader object that loads objects from the disk or from a ZIP archive, depending on the platform. It has state (e.g. the path to the directory or the ZIP archive, and possibly some ...
1
vote
1answer
82 views

How to get a reference to a central AssetLoader in every Widget?

I'm working on a simple UI system for a game. The building blocks are Widget objects, which can contain each other. There are several sub classes of Widget, e.g. LabelWidget, ImageWidgetand ...
4
votes
4answers
1k views

Are immutable/stateless singletons bad?

Lately there have been some kind of revolution against singletons, but is there something wrong with them if they are stateless? I know the overuse talk and all... this applies to everything not just ...
5
votes
3answers
905 views

How to create a manager class without global variables nor singletons?

I would like to implement some kind of manager class in my application. It will be in charge of loading textures, processing them, distributing them etc... At first, I wanted to make a global ...
10
votes
3answers
2k views

What are the downsides of implementing a singleton with Java's enum?

Traditionally, a singleton is usually implemented as public class Foo1 { private static final Foo1 INSTANCE = new Foo1(); public static Foo1 getInstance(){ return INSTANCE; } private ...
0
votes
5answers
408 views

should singleton be life-time available or should it be destroyable?

Should the singleton be designed so that it can be created and destroyed at any time in program or should it be created so that it is available in life-time of program. Which one is best practice? ...
3
votes
2answers
448 views

null values vs “empty” singleton for optional fields

First of all I'm developing a parser for an XML-based format for 3D graphics called XGL. But this question can be applied to any situation when you have fields in your class that are optional i.e. the ...
1
vote
3answers
229 views

Name for Osherove's modified singleton pattern?

I'm pretty well sold on the "singletons are evil" line of thought. Nevertheless, there are limited occurrences when you want to limit the creation of an object. Roy Osherove advises, If you're ...
3
votes
3answers
2k views

Is the singleton pattern prone to thread safety problems?

Is the singleton pattern prone to thread safety problems? If so, what are the best methods to work around them?
0
votes
0answers
68 views

Singletons in C++, are they really necessary, used? [duplicate]

Possible Duplicate: When is Singleton appropriate? Ok, most people probably know what a singleton is, use them, and know all the drawbacks including race conditions and so on. But what I ...
0
votes
2answers
177 views

Template rendering engine legitimate use of a singleton?

I wrote a standalone singleton class (scaffold) tonight that serves as a facade to a few other classes, including a template class and a view class. Templates and views are both named and instances ...
0
votes
5answers
385 views

Does “Property” in C# cost much?

I have a class created in some namespace, like SomeNameSpace.SubNameSpace.StaticClassName Here is a code snippet from other code file where I want to use this class many more times, so I created a ...
-1
votes
1answer
613 views

What is the difference between class level attributes, Class constants and singleton methods?

What the difference given they all exist 'once per class'. When should I use one over another, i.e. for what purpose? I use Ruby.
2
votes
1answer
765 views

const vs. readonly for a singleton

First off, I understand there are folk who oppose the use of singletons. I think it's an appropriate use in this case as it's constant state information, but I'm open to differing opinions / ...
20
votes
9answers
4k views

Alternatives to the singleton pattern

I have read different opinions about the singleton pattern. Some maintain that it should be avoided at all costs and others that it can be be useful in certain situations. One situation in which I ...
14
votes
7answers
6k views

What are the roles of singletons, abstract classes and interfaces?

I am studying OOP in C++ and, even though I am aware of the definitions of these 3 concepts, I cannot really realize when or how to use it. Let's use this class for the example: class Person{ ...
5
votes
4answers
729 views

C++ - Best way to have a central data repository

I'm coding in C++. I have a server that will have clients connect to it, and each client gets spun off into its own thread for communication. This server is hosting a game, so there is information ...
4
votes
1answer
663 views

DAO/Webservice Consumption in Web Application

I am currently working on converting a "legacy" web-based (Coldfusion) application from single data source (MSSQL database) to multi-tier OOP. In my current system there is a read/write database with ...
3
votes
3answers
7k views

Static class vs Singleton class in C# [duplicate]

Possible Duplicate: What is the difference between all-static-methods and applying a singleton pattern? I need to make a decision for a project I'm working of whether to use static or ...
10
votes
4answers
3k views

Dependency Injection and Singleton. Are they two entirely different concepts?

I've been hearing about using the dependency injection over Singleton for my colleague. I still can't make out if it they are two orthogonal patterns which can be replaced with one another? Or is DI a ...
1
vote
3answers
464 views

Memory problems with singletons in a test suite

I am having a memory leak when running a test suite due to singleton objects are created and not cleared after each test case. And these singleton objects are holding references to heavy objects. So ...
8
votes
4answers
446 views

Is there is a case when there is no any reasonable replacement for singleton design pattern? [duplicate]

Possible Duplicate: When is Singleton appropriate? I've seen many explanations why is Singleton is evil. But is there really no such a case when Singleton is the only beautiful solution?
0
votes
1answer
133 views

Is using Singleton correct for Jtree & DefaultTreeModel?

Basically I have one Tree view which uses a single DefaultTreeModel. Is it okay to use singleton for Tree extending JTree and another singleton for TreeModel extending DefaultTreeModel? If not, what ...
1
vote
6answers
2k views

Static classes and/or singletons — How many does it take to become a code smell? [closed]

In my projects I use quite a lot of static classes. These are usually classes that naturally seem to fit into a single-instance type of thing. Many times I use static classes and recently I've started ...
12
votes
5answers
909 views

What to say to your boss if they want you to use a global variable

I am currently 4 months into an internship, and when reviewing my code, my boss didn't like that I had kept a specific object local to a number of methods across a few separate classes within one ...
23
votes
7answers
2k views

The Singleton Pattern [duplicate]

Possible Duplicate: When is Singleton appropriate? I am a new programmer (4 months into my first job) and have recently taken an interest in design patterns. One that I have used recently ...
13
votes
5answers
5k views

What is the difference between all-static-methods and applying a singleton pattern?

I am making a database to store information about the users of my website (I am using stuts2 and hence Java EE technology). For the database I'll be making a DBManager. Should I apply singleton ...
4
votes
2answers
332 views

Are the default objects of VB a type of singleton?

Are the default objects supported by My keyword in VB.net is a kind of singleton? If not, what is the difference? Again is this "default object" feature is something useful? If yes, then why it is ...
11
votes
4answers
767 views

Does “notification center” pattern encourage good or bad program design?

Sometimes I come across these message-hub-style APIs, for example the Cocoa NSNotificationCenter: ...
37
votes
5answers
2k views

When is Singleton appropriate?

Some hold that the Singleton Pattern is always an anti-pattern. What do you think?