In object-oriented programming, the singleton pattern is a software design pattern that restricts the instantiation of a class to a singular instance. It is one of the well-known "Gang of Four" design patterns, which describe how to solve recurring problems in object-oriented software.[1] The pattern is useful when exactly one object is needed to coordinate actions across a system.
More specifically, the singleton pattern allows classes to:[2]
- Ensure they only have one instance
- Provide easy access to that instance
- Control their instantiation (for example, hiding the constructors of a class)
The term comes from the mathematical concept of a singleton.
- ^ Erich Gamma, Richard Helm, Ralph Johnson, John Vlissides (1994). Design Patterns: Elements of Reusable Object-Oriented Software. Addison Wesley. pp. 127ff. ISBN 0-201-63361-2.
{{cite book}}: CS1 maint: multiple names: authors list (link) - ^ "The Singleton design pattern - Problem, Solution, and Applicability". w3sDesign.com. Retrieved 2017-08-16.