isset()会触发__get吗，为什么? [英] Will isset() trigger __get and why?

问题描述

class a {
   function __get($property){...}
}

$obj = new a();
var_dump(isset($obj->newproperty));

似乎答案不是，但是为什么呢?

Seems the answer is nope but why?

推荐答案

因为它检查

Because it checks __isset rather than retrieving it using __get.

调用__isset是更好的选择，因为对于空值没有标准.也许在类的上下文中，null是一个可接受的值.您还可以拥有一个类，如果该成员不存在，它将返回一个新的空对象，该对象将破坏isset($myObj->item)，因为在这种情况下它将始终返回true.

It is a much better option to call __isset, as there is no standard on what is empty. Maybe in the context of the class null is an acceptable value. You could also have a class that if the member didn't exist, it returned a new empty object, which would break isset($myObj->item) as in that case it would always return true.

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