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8 years ago
> Members declared protected can be accessed only within 
> the class itself and by inherited classes. Members declared 
> as private may only be accessed by the class that defines 
> the member.

This is not strictly true. Code outside the object can get and set private and protected members:

<?php
class Sealed { private $value = 'foo'; }

$sealed = new Sealed;
var_dump($sealed); // private $value => string(3) "foo"

call_user_func(\Closure::bind(
    function () use ($sealed) { $sealed->value = 'BAZ'; },
    null,
    $sealed
));

var_dump($sealed); // private $value => string(3) "BAZ"

?>

The magic lay in \Closure::bind, which allows an anonymous function to bind to a particular class scope. The documentation on \Closure::bind says:

> If an object is given, the type of the object will be used
> instead. This determines the visibility of protected and
> private methods of the bound object.

So, effectively, we're adding a run-time setter to $sealed, then calling that setter. This can be elaborated to generic functions that can force set and force get object members:

<?php
function force_set($object, $property, $value) {
    call_user_func(\Closure::bind(
        function () use ($object, $property, $value) {
            $object->{$property} = $value;
        },
        null,
        $object
    ));
}

function force_get($object, $property) {
    return call_user_func(\Closure::bind(
        function () use ($object, $property) {
            return $object->{$property};
        },
        null,
        $object
    ));
}

force_set($sealed, 'value', 'quux');
var_dump(force_get($sealed, 'value')); // 'quux'

?>

You should probably not rely on this ability for production quality code, but having this ability for debugging and testing is handy.
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