Single-instance mode-php implementation-PHP Tutorial

Single-instance mode: php implementation. The Singleton mode ensures that a class has only one instance. 1. the static member variable stores the unique instance of the class. 2. the constructor and cloning method are declared to be private to prevent the new instance from being 3, provides a singleton mode to ensure that a class has only one instance;

1. the static member variable saves the unique instance of the class.

2. declare the constructor and clone method as private to prevent a new instance.

3. provide a public static method to access this instance and return the reference of a unique instance.

Class InstanceDemo

{

Private static $ _ instance; // The static member variable to save the unique instance.

Private function _ construct () // Constructor

{

Echo 'I am construceted ';

}

Public static function GetInstance ()

{

If (! Isset (self ::$ _ instance ))

{

$ C =__ CLASS __;

Self: $ _ instance = new $ c; // new self ()

}

Return self: $ _ instance;

}

// Overwrite the _ clone () method to disable cloning.

Private function _ clone ()

{

Echo "clone prohibited ";

}

Function test ()

{

Echo ("test instance ");

}

}

// Call the static common method to obtain a unique instance

$ Test = InstanceDemo: GetInstance ();

$ Test-> test ();

// Clone prohibited

$ Test_clone = clone $ test;

?>

Lifecycle 1, static member variables save the unique instance of the class 2, declare the constructor and clone method as private, prevent new instance 3, provide...