PHP - Indirect modification of overloaded property

Question

I know this question has been asked several times, but none of them have a real answer for a workaround. Maybe there\'s one for my specific case.

I\'m building a map

Answer 1

I've had this same error, without your whole code it is difficult to pinpoint exactly how to fix it but it is caused by not having a __set function.

The way that I have gotten around it in the past is I have done things like this:

$user = createUser();
$role = $user->role;
$role->rolename = 'Test';

now if you do this:

echo $user->role->rolename;

you should see 'Test'

Answer 2

Nice you gave me something to play around with

Run

class Sample extends Creator {

}

$a = new Sample ();
$a->role->rolename = 'test';
echo  $a->role->rolename , PHP_EOL;
$a->role->rolename->am->love->php = 'w00';
echo  $a->role->rolename  , PHP_EOL;
echo  $a->role->rolename->am->love->php   , PHP_EOL;

Output

test
test
w00

Class Used

abstract class Creator {
    public function __get($name) {
        if (! isset ( $this->{$name} )) {
            $this->{$name} = new Value ( $name, null );
        }
        return $this->{$name};
    }

    public function __set($name, $value) {
        $this->{$name} = new Value ( $name, $value );
    }



}

class Value extends Creator {
    private $name;
    private $value;
    function __construct($name, $value) {
        $this->name = $name;
        $this->value = $value;
    }

    function __toString()
    {
        return (string) $this->value ;
    }
}      

Edit : New Array Support as requested

class Sample extends Creator {

}

$a = new Sample ();
$a->role = array (
        "A",
        "B",
        "C" 
);


$a->role[0]->nice = "OK" ;

print ($a->role[0]->nice  . PHP_EOL);

$a->role[1]->nice->ok = array("foo","bar","die");

print ($a->role[1]->nice->ok[2]  . PHP_EOL);


$a->role[2]->nice->raw = new stdClass();
$a->role[2]->nice->raw->name = "baba" ;

print ($a->role[2]->nice->raw->name. PHP_EOL);

Output

 Ok die baba

Modified Class

abstract class Creator {
    public function __get($name) {
        if (! isset ( $this->{$name} )) {
            $this->{$name} = new Value ( $name, null );
        }
        return $this->{$name};
    }

    public function __set($name, $value) {
        if (is_array ( $value )) {
            array_walk ( $value, function (&$item, $key) {
                $item = new Value ( $key, $item );
            } );
        }
        $this->{$name} = $value;

    }

}

class Value {
    private $name ;
    function __construct($name, $value) {
        $this->{$name} = $value;
        $this->name = $value ;
    }

    public function __get($name) {
        if (! isset ( $this->{$name} )) {
            $this->{$name} = new Value ( $name, null );
        }

        if ($name == $this->name) {
            return $this->value;
        }

        return $this->{$name};
    }

    public function __set($name, $value) {
        if (is_array ( $value )) {
            array_walk ( $value, function (&$item, $key) {
                $item = new Value ( $key, $item );
            } );
        }
        $this->{$name} = $value;
    }

    public function __toString() {
        return (string) $this->name ;
    }   
}

Answer 3

All you need to do is add "&" in front of your __get function to pass it as reference:

public function &__get ( $index )

Struggled with this one for a while.

Answer 4

I was receiving this notice for doing this:

$var = reset($myClass->my_magic_property);

This fixed it:

$tmp = $myClass->my_magic_property;
$var = reset($tmp);

Answer 5

I agree with VinnyD that what you need to do is add "&" in front of your __get function, as to make it to return the needed result as a reference:

public function &__get ( $propertyname )

But be aware of two things:

1) You should also do

return &$something;

or you might still be returning a value and not a reference...

2) Remember that in any case that __get returns a reference this also means that the corresponding __set will NEVER be called; this is because php resolves this by using the reference returned by __get, which is called instead!

So:

$var = $object->NonExistentArrayProperty; 

means __get is called and, since __get has &__get and return &$something, $var is now, as intended, a reference to the overloaded property...

$object->NonExistentArrayProperty = array(); 

works as expected and __set is called as expected...

But:

$object->NonExistentArrayProperty[] = $value;

or

$object->NonExistentArrayProperty["index"] = $value;

works as expected in the sense that the element will be correctly added or modified in the overloaded array property, BUT __set WILL NOT BE CALLED: __get will be called instead!

These two calls would NOT work if not using &__get and return &$something, but while they do work in this way, they NEVER call __set, but always call __get.

This is why I decided to return a reference

return &$something;

when $something is an array(), or when the overloaded property has no special setter method, and instead return a value

return $something;

when $something is NOT an array or has a special setter function.

In any case, this was quite tricky to understand properly for me! :)

Answer 6

I have run into the same problem as w00, but I didn't had the freedom to rewrite the base functionality of the component in which this problem (E_NOTICE) occured. I've been able to fix the issue using an ArrayObject in stead of the basic type array(). This will return an object, which will defaulty be returned by reference.