Modifying a PHP array element via magic methods (get and set)

Question

I have the following class:

/**
 * @property int $barMagic
 */
class Foo
{
    public $barNormal;

    private $attributes = [];

    public function __get($name) {
        return isset($this->attributes[$name]) ? $this->attributes[$name] : null;
    }

    public function __set($name, $value)
    {
        $this->attributes[$name] = $value;
    }
}

As you can see, the $barMagic public property is not defined explicitly, it's accessed via the magic methods.

When setting and then modifying an array element in the normal attribute, it works fine:

$foo = new Foo();
$foo->barNormal = ['baz' => 1];
echo $foo->barNormal['baz'];
$foo->barNormal['baz'] = 2;
echo ',' . $foo->barNormal['baz'];

It outputs "1,2", just as intended.

But when using the magic property, it does not:

$foo = new Foo();
$foo->barMagic = ['baz' => 1];
echo $foo->barMagic['baz'];
$foo->barMagic['baz'] = 2;
echo ',' . $foo->barMagic['baz'];

It outputs "1,1"!

Is there a way in PHP to access array elements in magic properties the same way as normal ones?

The ArrayAccess interface seems to deal with array access one level higher than I need it.

Turn on all warnings and you'll see "E_NOTICE : type 8 -- Indirect modification of overloaded property Foo::$barMagic has no effect -- at line XX" — Henrique Barcelos, Aug 11 '15 at 15:20
Please refer to: http://stackoverflow.com/questions/10454779/php-indirect-modification-of-overloaded-property — Henrique Barcelos, Aug 11 '15 at 15:21

score 0 · Answer 1 · answered Aug 11 '15 at 15:41

The real answer is tricky and involves some bug/inconsistency in the PHP engine. As commentors suggested, I added the "&" (return by reference) character before __get(). So new code:

public function &__get($name) {
    return isset($this->attributes[$name]) ? $this->attributes[$name] : null;
}

but this gives

Notice: Only variable references should be returned by reference in ....

I had to change it to

public function &__get($name) {
    if (isset($this->attributes[$name])) {
        return $this->attributes[$name];
    } else {
        return null;
    }
}

and now it works. Note that the two snippets should be completely equivalent, but they are not. Thank you all for the contribution, you took me halfway there.

This would be interesting in the `else` case, as I don't think you can return a reference to `null`. Need to test this though. — Bert Peters, Aug 11 '15 at 15:50

Modifying a PHP array element via magic methods (__get and __set)

1 Answers1

Modifying a PHP array element via magic methods (get and set)