public static function get_instance() { if (!isset(self::$instance)) { self::$instance = new G1(); } return self::$instance; }
<?php $a1 = 1; $a1 = 2; $b2 = 1; $c2 = 3; $b2 = 2; $c1['3'] = 3; $c1['3'] = 4; $d1['4'] = 4; $d1['5'] = 5; $e2->f = 3; $e2->g = 3; $e1->f2 = 4; $e1->f2 = 3; G1::$f1 = 4; G1::$f1 = 5; G2::$f2 = 4; G2::$g1 = 5; G2::$f2 = 4; G2::$g1 = 5; G1::$f1->p = 4; G1::$f1->p = 5; G2::$f1->p = 4; G2::$f1->h = 5;