CODEWITHSUNDEEP
phpsubclassingoverriding
Reese
Reese

Reputation: 1775

How can a parent class's method access an subclass's overridden variable?

If I have a subclass that is overriding a protected variable, and the parent class has the function to do stuff with that variable, how do I get that function to use the value it is overridden with?

class Superclass {
    protected $map;

    public function echoMap()
    {
        foreach ($this->map as $key=>value)
        {
            echo "$key:$value";
        }
    }
}

and

class Subclass extends Superclass {
    protected $map = array('a'=>1, 'b'=>2);
}

and when I run the following

$subclass = new Subclass();
$subclass->echoMap();

I would expect it to return 

a:1
b:2

but $this->map is empty in the parent class. What should I do instead to get the behavior I want?

Edit: There was a bug in the constructors, not in the example posted above. It works as expected.

Upvotes: 1

Views: 1501

Answers (2)

K2xL
K2xL

Reputation: 10290

Even though it looks to be just a typo (not extending the super class), you should try initializing your variables in the constructor of both classes.

function __construct() { // initialize protected values }

Upvotes: 0

mfonda
mfonda

Reputation: 7993

PHP does work the way you describe. The only thing I can see is in your example, Subclass does not extend Superclass. I assume this is a mistake in your example only. Check to make sure all classes actually do extend the correct class, and check to make sure you have no typos in variable names.

See http://codepad.viper-7.com/kDrbIh for an example of it working.

Upvotes: 1

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