Monostate

<?php
class Monostate {
    // 属于类不属于对象
    private static $_val = 0; 
    public function Monostate(){
        
    }
    public function set($val) {
        self::$_val = $val;
    }
    
    public function get() {
        return self::$_val;
    }
}


$m1 = new Monostate();
$m2 = new Monostate();
$m1->set(5);
echo $m2->get();// 5