抛出异常后无法访问类的属性

Question

I have a PHP class which for this example I'm just calling MyClass . If something goes wrong in this class, it throws an exception which I'm catching. In this catch block, I need to access some public class properties of MyClass but for some reason they're all returning NULL . Code below.

try {
    $myClass= new \sys\global\MyClass($id);
} catch (Exception $e) {
    die(var_dump($myClass->reading));
}

The above is printing NULL to the page, even though reading is a public property of MyClass :

namespace sys\global;

class MyClass {
    public $reading = 10;

    // ... other class code
}

I've even done die(var_dump($this->reading)) inside the class just before the exception is thrown and it has the value 10 .

Does throwing an exception in a class destroy it?

Answer 1

If an exception is thrown inside the constructor, the object is not created. ie You can't access the attributes of an object that does not exist.

Answer 2

Depending on what the exception was, you may not be able to access the members. It would appear in this situation that your exception is caused in the constructor of $myClass , so I doubt your object is getting created properly, therefore meaning you can't access its properties.