/**
* Test the getInstance method
*/
public function testSingleton()
{
$a1 = A::getInstance();
$a2 = A::getInstance();
$this->assertEquals($a1, $a2);
$b = B::getInstance();
$this->assertNotEquals($a1, $b);
}
<?php
trait Singleton
{
protected static $_instance = null;
public static function getInstance()
{
if (static::$_instance === null || !static::$_instance instanceof static) {
static::$_instance = new static();
}
return static::$_instance;
}
}
class A
{
use Singleton;
private function __construct()
{
}
}
$a = A::getInstance();
var_dump($a instanceof A);
var_dump($a instanceof Singleton);
var_dump(is_a($a, 'Singleton'));
function main()
{
// the interpreter should correctly go to A::foo
A::getInstance()->foo();
}
