Shulou(Shulou.com)06/01 Report--

Today, the editor will share with you the relevant knowledge about the advantages of Singleton mode. The content is detailed and the logic is clear. I believe most people still know too much about this knowledge, so share this article for your reference. I hope you can get something after reading this article. Let's take a look at it.

The Singleton model has many advantages:

1) controlled access to unique instances

Because the Singleton class encapsulates its unique instance, it has strict control over how and when customers access it.

For the access control of data, it is generally necessary to solve the problem of which data and when to be accessed. Of these two questions, the question of that data is more important. The singleton mode ensures that there is only one instance available, and the rest of the monitoring becomes simple.

2) reduce the name space

The Singleton pattern is an improvement on global variables. It prevents global variables that store unique instances from polluting the name space.

Global variables and singletons have similar characteristics at the execution level, but they are very different at the compilation (coding) level. The instance is obtained through the class method of Singleton, which does not occupy the variable name as global variables do.

3) allow refinement of operations and representations

The Singleton class can have subclasses, and it is easy to configure an application with an instance of this extension class. You can configure the application at run time with an instance of the class you need.

The word refinement is originally refinement, which here should mean refinement and concretization. Singleton returns the base class type, but because the actual creation of the object is encapsulated inside the class, it is convenient to return objects of a specific subclass when generating an instance.

4) allow a variable number of instances

This pattern makes it easy for you to change your mind and allows multiple instances of the Singleton class. In addition, you can use the same method to control the number of instances used by the application. Only allow access to Singleton

The operation of the instance needs to change.

Maybe the designer initially imagined that there was only one instance of this class, but then the idea changed. At this point, singleton mode can be used as long as you ensure that only one object is allowed to be accessed. This degree of change will not affect the user.

5) more flexible than class operation

Another way to encapsulate singleton functionality is to use class operations (that is, static member functions in C++ or class methods in Smalltalk). However, neither of these language technologies can change the design to allow multiple instances of a class. In addition, static member functions in C++ are not virtual functions, so subclasses cannot polymorphic redefine them.

Although you can also use class operations (static functions) to achieve the same functionality of the singleton pattern, because it is difficult to implement multiple instances and redefine operations, the singleton mode is preferred.

These are all the contents of this article entitled "what are the advantages of Singleton mode?" Thank you for reading! I believe you will gain a lot after reading this article. The editor will update different knowledge for you every day. If you want to learn more knowledge, please pay attention to the industry information channel.

Welcome to subscribe "Shulou Technology Information " to get latest news, interesting things and hot topics in the IT industry, and controls the hottest and latest Internet news, technology news and IT industry trends.