Why should I need "&"?

See example on the web about the PHP Factory Pattern.

In the line $kind =& Vehicle::category($wheel); , why should I to use & ?

The code:

<?php
    class Vehicle {

        function category($wheel = 0) {
            if ($wheel == 2) {
                return "Motor";
            } elseif($wheel == 4) {
                return "Car";
            }
        }
    }

    class Spec {

        var $wheel = '';

        function Spec($wheel) {
            $this->wheel = $wheel;
        }

        function name() {
            $wheel = $this->wheel;
                return Vehicle::category($wheel);
        }

        function brand() {
            $wheel = $this->wheel;
                $kind =& Vehicle::category($wheel);
            if ($kind == "Motor") {
                return array('Harley','Honda');
            } elseif($kind = "Car") {
                return array('Nisan','Opel');
            }
        }
    }

    $kind = new Spec(2);
    echo "Kind: ".$kind->name();
    echo "<br>";
    echo "Brand: " . implode(",", $kind->brand());
?>

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这里没有用，因为这个例子得到了一个常量的引用，但是当你想要“观察”一个可能会改变的值时，引用确实有用，并且你希望你的变量随它改变。

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From Stack Overflow question Reference - What does this symbol mean in PHP?:

=& References

Reference assignment operator in PHP, =&

What do the "=&" and "&=" operators in PHP mean?

What do the '&=' and '=&' operators do?

What does =& mean in PHP?

As the (deleted) comment said, the last link should apply to your specific case.

链接地址: http://www.djcxy.com/p/57594.html

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