PHP design mode-singleton mode (singleton)

Before you learn this singleton mode, please choose to read another design mode

PHP design mode-Simple Factory mode (static Factory method mode)

PHP design mode-factory method mode (polymorphism Factory mode) (virtual construction sub-mode)

PHP design mode-Abstract Factory mode

As an object's creation mode, Singleton mode ensures that a class has only one instance, and instantiates it itself and provides it to the entire system, a class called a singleton class

The singleton mode (singleton) has three features
1. Only one instance of a class
2. It must create this instance on its own
3. It must provide this instance to the entire system on its own

Legend:

code example:

Singleton mode is divided into lazy singleton patterns in Java | a hungry man single-case mode

However, the A hungry man singleton mode is not available in PHP, and I will list the code below, which will prompt the error at run-time. Here is just a concept of usage.

A hungry man single-case mode:

1 //This is the A Hungry man single-case pattern .2 //But in PHP, this is not allowed to be practical. So we're basically talking about PHP's lazy singleton pattern.3 classTest {4     Private Static $_instance=NewSelf ();5 6      Public Static functiongetinstance () {7         returnSelf::$_instance;8     }9 Ten     Private function__construct () { One         //Check instantiation A         Echo"Instance\n"; -     } -  the } - $a= Test::getinstance (); - Var_dump($a);

Lazy single-case mode:

1 //Lazy Single-case mode2 3 classTest {4     Private Static $_instance;5 6      Public Static functiongetinstance () {7         if(!self::$_instance){8Self::$_instance=NewSelf ();9         }Ten         returnSelf::$_instance; One     } A  -     Private function__construct () { -         //Check instantiation the         Echo"Instance\n"; -     } -  - } +  - $a= Test::getinstance (); + Var_dump($a);

PHP design mode-singleton mode (singleton)