What is the use of singleton pattern in php

The role of the singleton mode in php: The singleton mode can ensure that there is only one instance of a certain class, and it instantiates itself and provides this instance to the entire system. Characteristics of the singleton pattern: 1. A class can only have one instance; 2. The class must create its own instance; 3. The class must provide its own instance to the system.

php singleton mode can be applied to database operation classes, website counters, application log applications and the acquisition of web application configuration objects.

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Design pattern? Sounds lofty? That's true. Design pattern is a way of organizing code, which means that the code is no longer executed one by one. Instead, the code is organized more effectively according to the effective methods summarized by predecessors, which is more efficient and looks clear. Orderly.

php singleton mode, as the name suggests, has only one instance. As an object creation mode, the singleton mode ensures that there is only one instance of a certain class, and it instantiates itself and provides this instance to the entire system. This class is called a singleton class.

The singleton mode has three characteristics:

1. There can only be one instance of a certain class.

2. This class must create this instance by itself.

3. This class must provide this instance to the system by itself.

Use of singleton mode

(1) Singleton mode can be applied to database operation classes

(2) Singleton mode can Applied to the counter of the website

(3) The log application of the application is generally implemented in the singleton mode. This is usually because the shared log file is always open, because there can only be one instance to operation, otherwise the content will not be added.

(4) The singleton mode is generally used to read the configuration object of the web application. This is because the configuration file is a shared resource.

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