转：https://blog.csdn.net/baidu_30000217/article/details/49666647
类的类型提示 - 将类名放在需要约束的方法参数之前
语法格式：
public function write(ShopProduct $shopProduct){}
数组提示：
public function setArray(array $storearray){}
class ShopProduct{ ???public $title = ‘default product‘; ?????// 属性也称为成员变量，用来存放对象之间互不相同的数据 ???public $producerMainName = ‘main name‘; ???public $producerFirstName = ‘first name‘; ???public $price = 0; ???// 创建对象时，构造方法会被自动调用，构造方法可以确保必要的属性设置，并完成任何需要准备的工作 ???public function __construct($title,$producerMainName,$producerFirstName,$price){ ???????$this->title = $title; ?????// 使用伪变量$this给每个变量赋值 ???????$this->producerMainName = $producerMainName; ???????$this->producerFirstName = $producerFirstName; ???????$this->price = $price; ???} ???public function getProducer(){ ?// 方法让对象执行任务 ???????return $this->producerMainName . $this->producerFirstName; ???}}class ShopProductWriter{ ???public function write(ShopProduct $shopProduct){ ???// 类的类型提示，只需将类名放在需要约束的方法参数之前 ???????$str = $shopProduct->title . ‘:‘ . $shopProduct->getProducer() . "($shopProduct->price) . </br>"; ???????print $str; ???} ???public function setArray(array $storearray){ ???????// 数组提示 ???????var_dump($storearray); ???} ???public function setWriter(ObjectWriter $objectWriter=null){ ???????var_dump($objectWriter); ???}}class Wrong{};$store = array(‘name‘=>‘taobao‘);$objectWriter = NULL;$product1 = new ShopProduct(‘My Antonia‘,‘Willa‘,‘Cather‘,5.99); ???// 更易于实例化，也更安全，实例化和设置只需要一条语句就可以完成，任何使用ShopProduct对象的代码都可以相信所有的属性皆被初始化了$writer = new ShopProductWriter();$writer->write($product1); ???????// 有了参数提示，规定此处只能传入new ShopProduct对象$writer->write(new Wrong()); ????// 传入其它的对象会出现：Catchable fatal error: Argument 1 passed to ShopProductWriter::write() must be an instance of ShopProduct, instance of Wrong given..从而防止隐藏bug的产生。$writer->setArray($store); ???????// 有了参数提示，规定此处只能传入一个数组$writer->setWriter($objectWriter); // 有了参数提示，规定此处只能传入NULL
php传入对象时获得类型提示(类约束)
原文地址：https://www.cnblogs.com/jimz/p/9393664.html