These two simple functions can come in handy as helpers for something like PsySH. PHP >= 7.0 is required.

NB: Don't use them in actual production code! That would be awful

Call private method of an object:

<?php
function call_private_method($object, string $method, ...$args)
{
    return (function ($method, ...$args) {
        return call_user_func_array([$this, $method], $args);
    })->call($object, $method, ...$args);
}

Get private field of an object:

<?php
function get_private_field($object, string $field)
{
    return (function ($field) {
        return $this->$field;
    })->call($object, $field);
}

Example:

<?php
class A
{
    private $secret = 'SECRET234';

    private function doStuff($whatever)
    {
        return $whatever . '!';
    }
}

$a = new A;

get_private_field($a, 'secret'); // SECRET234

call_private_method($a, 'doStuff', 'whatever'); // whatever!

UPD: "Why not make a library out of it", I thought. So it's now a library: github.com