<?php
class type_a{
public $val = 1;
}

function main(type_a $object){
var_dump($object);
}

$new_type_a = new type_a;
main($new_type_a);
//结果会是
//object(type_a)#1 (1) {
// ["val"]=>
// int(1)
//}

//如果你给的参数不是type_a类产生的对象.

$new_object = 1;//实际上 int 是一种内置类型
main($new_object);
////这将会报错
//Catchable fatal error: Argument 1 passed to main() must be an instance of type_a, integer given