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What is singleton application?
In software engineering, the singleton pattern is a software design pattern that restricts the instantiation of a class to one “single” instance. This is useful when exactly one object is needed to coordinate actions across the system. The term comes from the mathematical concept of a singleton.
What is the singleton pattern when should it be used?
Use the Singleton pattern when a class in your program should have just a single instance available to all clients; for example, a single database object shared by different parts of the program. The Singleton pattern disables all other means of creating objects of a class except for the special creation method.
When to use a singleton in an application?
You should use a Singleton when there should only be one instance of an object. However, Misko Hevery has some thoughts on why Singletons are bad! One way I’ve used a singleton is to implement a “main controller” object for an application. This was a bit like the Application object you get with VBA.
How are configuration classes implemented as a singleton?
By implementing configuration classes as Singleton not only that we provide a global access point, but we also keep the instance we use as a cache object. When the class is instantiated( or when a value is read ) the singleton will keep the values in its internal structure.
Which is an excellent use of the singleton pattern?
I think an application configuration is an excellent use of the Singleton pattern. I tend to use it myself to prevent having to reread the configuration each time I want to access it and because I like to have the configuration be strongly typed (i.e, not have to convert non-string values each time).
How are global access points represented in singleton pattern?
Global Access Point represented by the class name- The singleton instance is obtained using the class name. At the first view this is an easy way to access it, but it is not very flexible. If we need to replace the Sigleton class, all the references in the code should be changed accordinglly.