Question

abstract class foo
{
    public $blah;
}

class bar extends foo
{
    public $baz;
}

Given that I have a foo class that inherits from the abstract bar class how would I get an array of the instance variables that exist only on bar but not on foo (i.e. properties that are defined on the bar level)? In the example above I would want baz but not blah.

Answer 1

As hakre said, use Reflection. Grab the class’s parent class, and do a diff on the properties, like so:

function get_parent_properties_diff( $obj) {
    $ref = new ReflectionClass( $obj);
    $parent = $ref->getParentClass();
    return array_diff( $ref->getProperties(), $parent->getProperties());
}

You’d call it like this:

$diff = get_parent_properties_diff( new bar());
foreach( $diff as $d) {
    echo $d->{'name'} . ' is in class ' . $d->{'class'} . ' and not the parent class.' . "\n";
}

See it working in this demo, which outputs:

baz is in class bar and not the parent class.