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Topic: Singleton pattern

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Creational pattern

Adapter pattern

Abstract factory pattern

Structural pattern

Design pattern (computer science)

State pattern

Fundamental pattern

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Factory method pattern

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	Singleton Pattern
		Singletons are most appropriate for services that do not change their nature based on their invocation context.
		Singletons are very similar to GlobalVariables, and are often implemented with global variables, even if they masquerade as class members.
		Every singleton class is done as an abstract base class and the actual objects constructed in the main line are instances of particular derived classes.
	c2.com /cgi/wiki?SingletonPattern (4922 words)

	Java Singleton Design Pattern
		Java Singleton pattern belongs to the family of design patterns, that govern the instantiation process.
		The Singleton class’s default constructor is made private, which prevents the direct instantiation of the object by others (Other Classes).
		In Summary, the job of the Singleton class is to enforce the existence of a maximum of one object of the same type at any given time.
	www.beginner-java-tutorial.com /singleton.html (677 words)

	A Generic Singleton Pattern in C# - Sanity Free dot org - C#, .NET, PHP
		A Generic Singleton Pattern in C# I don't know why its never occured to me to implement the singleton pattern as a generic type before.
		I've always just created the singleton pattern as part of my class (not that we're talking about a lot of coding here), but it occured to me that a singleton could be a lot easier to implement and spot if I used a generic type.
		Now, this doesnt keep you from creating non singleton objects of whatever type you have (there may still be some clever way to do that, but I'm not familiar with it), but it does save you the time of implementing the singleton pattern on singleton objects.
	sanity-free.org /132/generic_singleton_pattern_in_csharp.html (209 words)

	Exploring the Singleton Design Pattern (Site not responding. Last check: )
		For the scope of this article, we are going to discuss the Singleton pattern, which lives in a family of creational patterns.
		The intent of the Singleton pattern as defined in Design Patterns is to "ensure a class has only one instance, and provide a global point of access to it".
		The GoF Singleton pattern details the issues with trying to subclass a singleton and it is generally not a trivial matter.
	msdn.microsoft.com /library/default.asp?url=/library/en-us/dnbda/html/singletondespatt.asp (2922 words)

	The Singleton Pattern, and the Observer Pattern Tech Tips
		The Singleton pattern is useful if you know you only have a single resource, and need to share access to the state information of that single resource.
		A Singleton pattern is often used with another pattern called the Factory pattern.
		Like the Singleton Pattern, which was covered in the first half of this tip, the Observer pattern is a popular design pattern used in Java programs.
	java.sun.com /developer/JDCTechTips/2006/tt0113.html (2055 words)

	NationMaster - Encyclopedia: Singleton pattern
		The singleton pattern is implemented by creating a class with a method that creates a new instance of the object if one does not exist.
		The singleton pattern is often used in conjunction with the factory method pattern to create a system-wide resource whose specific type is not known to the code that uses it.
		Regarding the singleton pattern, you have to create the function for every singleton class you want to have, because settting a variable static will set the variable on all instances of the class, and second of all, by extending a singleton class, you are breaking rule No #1 of the singleton pattern.
	www.nationmaster.com /encyclopedia/Singleton_pattern/ActionScript_3_Example_Implementation (470 words)

	Singleton pattern - Wikipedia, the free encyclopedia
		The singleton pattern is implemented by creating a class with a method that creates a new instance of the object if one does not exist.
		The singleton pattern must be carefully constructed in multi-threaded applications.
		The singleton pattern is often used in conjunction with the factory method pattern to create a system-wide resource whose specific type is not known to the code that uses it.
	en.wikipedia.org /wiki/Singleton_pattern (1115 words)

	XML.com: Design Patterns in XML Applications: Part II (Site not responding. Last check: )
		The following pattern is a typical XADP, called the "XMLable pattern." It has been successfully used in a number of applications, and tackles one common problem in XML-aware applications: the construction of internal representations of XML data as meaningful objects.
		The XMLable pattern defines a solution to managing information that is persisted as XML data, but must also be managed as meaningful objects (i.e., not as a general data structure such as the DOM) inside an application.
		Singleton: The Singleton pattern ensures that only one instance of a class is created.
	www.xml.com /pub/a/2000/02/16/feature/index.html?page=2 (867 words)

	PHP: Patterns - Manual
		The singleton code is implemented in the parent so no rewriting of the code is necessary, thus avoiding programmer mistakes in the childclasses and keeping the code cleaner to the eye.
		Regarding the singleton pattern, you have to create the function for every singleton class you want to have, because settting a variable static will set the variable on all instances of the class, and second of all, by extending a singleton class, you are breaking rule No #1 of the singleton pattern.
		As Singleton patterns are used for years in Java, today we tend toward overriding 'new' operator (as singleton returns always the same instance for every 'new' that you call...).
	www.php.net /manual/en/language.oop5.patterns.php (3512 words)

	Ogre Forums :: View topic - why alwalys use getSingleton()
		You obviously missed where the book clearly states that the factory pattern can be implemented as a singleton (in the singleton chapter) or where it states that a factory is often a singleton (in the factory chapter) lol.
		Singleton and Factory go hand in hand, as in the vast majority of cases you want to be able to build classes from a factory from anywhere in the application, and you only want a single factory to exist.
		I'm not saying a problem cant fit into both singleton pattern and factory pattern im just saying that a factory doesnt have to be a singleton and a singleton doesnt have to be a factory.
	www.ogre3d.org /phpBB2/viewtopic.php?t=24287&view=previous (2067 words)

	Singleton Patterns in C#
		The singleton design pattern is used when only one instance of an object is needed throughout the lifetime of an application.
		The singleton class is instantiated at the time of first access and the same instance is used thereafter till the application quits.
		But by using a private constructor and a static method to create an instance of the class is a popular way to create singleton pattern.
	www.c-sharpcorner.com /Language/SingletonPatternsInCSharpRVS.asp (444 words)

	Kamal’s Blog
		As already discussed, Singleton pattern is used whenever we require a class to have only one instance throughout the application.
		A side effect of using singleton class: as the constructor of the singleton class is private, you cannot create a subclass of a singleton class, but in most of the cases that is desirable.
		Singleton pattern: As the name suggests, a singleton pattern refers to a pattern where you need only a ’single’ instance of a class to be present.
	www.kamalmeet.com (3332 words)

	Singleton
		The Singleton pattern ensures that a class has only one instance and provides a global point of access to that instance.
		The advantage of Singleton over global variables is that you are absolutely sure of the number of instances when you use Singleton, and, you can change your mind and manage any number of instances.
		Singletons are intended to be used when a class must have exactly one instance, no more, no less...
	home.earthlink.net /~huston2/dp/singleton.html (937 words)

	Singleton Pattern & its implementation with C++ - The Code Project - C++ / MFC
		Singleton is one of the commonly used patterns in object oriented developments.
		The Singleton class is instantiated at the time of first access and same instance is used thereafter till the application quits.
		The Singletons are often used to control access to resources such as database connections or sockets.
	www.codeproject.com /cpp/singletonrvs.asp (720 words)

	Lasagne/J and the Singleton Pattern
		The Singleton Pattern is intended to “Ensure a class only has one instance, and provide a global point of access to it”.
		One of the motivating examples of the Singleton pattern is that of a printer spooler.
		Using the Singleton pattern to implement the printer spooler ensures exactly that.
	www.lasagnej.org /Lasagne_J_Singleton_DP.htm (269 words)

	[No title]
		C++ Report "Pattern Hatching" column for June '96 issue John Vlissides Title: TO KILL A SINGLETON The Singleton pattern is remarkably simple.
		But one of the pattern's consequences is the option to control the number of instances, as opposed to flatly precluding more than one.
		Singleton's responsibilities imply that it owns the instance it creates; and ownership, finally, means responsibility for deletion.
	www.research.ibm.com /designpatterns/pubs/ph-jun96.txt (2448 words)

	Singleton pattern - Axaptapedia
		A singleton is a class which only allows a single instance of itself to be created.
		Usually, singleton classes use a static variable to hold a reference their own instance, but as Axapta does not support static variables we are forced to use the global caching mechanism to achieve the same effect.
		We should therefore override the new() method of our singleton class and use the private access modifier to ensure that it cannot be instantiated directly.
	www.axaptapedia.com /index.php/Singleton_pattern (211 words)

	CodeGuru Forums - Java Singleton Pattern Tutorial
		The Singleton Pattern is one of the commonly used design templates when there needs to be a control on how an object can be created.
		By making frequent use of the Singleton patterns you can claim your program is designed according to OO principles while it in fact is nothing like it.
		Singleton pattern shud defintely be used because of its simplicity in design which gives us so much control over an object created.
	www.codeguru.com /forum/showthread.php?threadid=406078 (1259 words)

	Singleton pattern - GPWiki
		The singleton pattern is implemented by creating a class with a method that creates a new instance of the object if one does not exist.
		In computer science, the singleton design pattern is designed to restrict instantiation of a class to one (or a few) objects.
		To use a singleton version of a class it will have to have one instance, so it would be wise to do a check to see if the instance is created before returning it, and create it if it does not exist.
	gpwiki.org /index.php/Programming_Techniques:Singleton (762 words)

	Introduction to Pattern Automation
		Writing a pattern involves a handfull of methods that are invoked by Together at certain times during the life cycle of the pattern application.
		pattern link is checked for in the selected class and, if present, the selected class is assigned the role of the singleton factory, otherwise it is assigned the role of the singleton.
		That means that if you selected this option and used the pattern to create a set of classes and interfaces, the pattern invoked for some participant later (via the popup menu item "Choose Pattern...") will automatically find (if it is possible) all other participants and fill in participant fields with their names.
	dn.codegear.com /article/29927 (3417 words)

	[No title]
		The singleton pattern applies to the many situations in which there needs to be a single instance of a class, a single object.
		One possible disadvantage to this pattern is that you may lose some functionality contained in the lower level of classes, but this depends on how the facade was designed.
		You, as the program architect, have decided that the facade pattern will be an excelent way to keep the amount of interfacing low, considering the number of possible objects in each room, and the actions that the client has specified.
	www.csc.calpoly.edu /~dbutler/tutorials/winter96/patterns/tutorial.html (760 words)

	J2EEPATTERNS-INTEREST archives -- December 2003 (#38)
		The main purpose of singleton is to restrict the number of object instances been created.
		Singleton pattern doesn't have all methods static, but only one (getInstance()).
		The Math class is an utility class,not a (GoF) pattern.
	archives.java.sun.com /cgi-bin/wa?A2=ind0312&L=j2eepatterns-interest&T=0&P=4464 (182 words)

	Dr. Dobb's \| Once Is Not Enough \| May 29, 2003
		Singletons are intended to be used when a class must have exactly one instance, no more, no less [2].
		Therefore the Singleton is not a global variable." "By the letter of the Holy Standard, yes, its scope is limited to the member function.
		The problem is not with Singletons, but with the rampant overzealous application of the Singleton pattern where not appropriate.
	www.ddj.com /184401625?_requestid=876403 (1166 words)

	Introducing the singleton - "The Single Java Object"
		For those who haven't heard of design patterns before, or who are familiar with the term but not its meaning, a design pattern is a template for software development.
		The singleton pattern can be applied in any language, but since we're all Java programmers here (if you're not, shame!) let's look at how to implement the pattern using Java.
		Creating an implementation of the singleton pattern is fairly straightforward - simple block off access to all constructors, provide a static method for getting an instance of the singleton, and prevent cloning.
	www.javacoffeebreak.com /articles/designpatterns/index.html (1187 words)

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