静态方法和非静态方法的互相调用，类调用非静态方法

静态方法调用非静态方法：

class Test{
    public function fn1(){
        echo 2*2;
//        $this->fn2();
    }

    public static function fn2(){
        echo 3*3;
        $obj = new Test;
        $obj->fn1();
    }
}
//$obj = new Test;
//$obj->fn1();
Test::fn2();

非静态方法调用静态方法：

class Test{
    public function fn1(){
        echo 2*2;
        $this->fn2();
    }

    public static function fn2(){
        echo 3*3;
//        $obj = new Test;
//        $obj->fn1();
    }
}
$obj = new Test;
$obj->fn1();
//Test::fn2();

可以基本实现，不会报错

类调用非静态方法：：

class Facades {
    public function __call($name, $params) {
        return call_user_func_array([$this, $name], $params);
    }
    public static function __callStatic($name, $params) {
        return call_user_func_array([new static(), $name], $params);
    }
}

class Cache extends Facades {
    protected function fn($a, $b) {
        echo "function parameters: ${a} and ${b}<br>";
    }
    protected function static_fn($a, $b) {
        echo "static function parameters: ${a} and ${b}<br>";
    }
}

Cache::fn(3,6);
Cache::static_fn(4,7);