PHP：OOP：返回错误

Question

How can I check if my object has returned false or not? I have the following class:

class Test {
    public function __construct($number) {
        if($number != '1') {
            return FALSE;
        }
    }
}

I've tried:

$x = new Test('1');
$x = new Test('2');

But when I var_dump($x), I get the same results. I want to do a:

if(! $x = new Test('1')) {
    header("location: xxx...");
}

Answer 1

You cannot return anything from a constructor. If you want the construction of an object to fail, you'll have to throw an Exception .

Answer 2

As deceze said, constructors cannot return a value. You could create a factory method that returns false, like:

class Test
{
    public function __construct($number) {
        ...
    }

    public function factory($number) {
        return ($number != '1') ? false : new self($number);
    }
}

$x = Test::factory('1');
if (!$x) {
    header('Location: ...');
}

But I would use exceptions instead

class Test
{
    public function __construct($number) {
        if ($number != '1') {
            throw new IllegalArgumentException('Number must be "1"');
        }
        ...
    }
}

try {
    $x = new Test('1');
} catch (Exception $e) {
    header('Location: ...');
}