PHP implementation of singleton mode_PHP tutorial

The singleton pattern ensures that there is only one instance of a class;

1. Static member variables save the only instance of the class

2. Declare the constructor and clone method as private to prevent new instances

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

class InstanceDemo

{

private static $_instance;//Static member variables save the only instance

private function __construct()//Constructor function

{

echo 'I am Construceted';

}

public static function GetInstance()

{

if(!isset(self::$_instance))

{

$c=__CLASS__;

                                                                                                                                                                                   

}

return self::$_instance;

}

//Override the __clone() method and disable cloning

private function __clone()

{

echo "clone prohibited";

}

function test()

{

echo("test instance");

}

}

//Call the static public method to get the only instance

$test = InstanceDemo::GetInstance();

$test->test();

//Cloneing is prohibited

$test_clone = clone $test;

?>

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