Thought experiments and lab experiments should be kept in different places...

thought_experiment.php

<?php
/**
 * @file
 * A thought experiment.
 */

class MyFakeThing {
}

// This is ... well, nothing special.
$original = new MyFakeThing();

// Make a copy. Just be sure to take it out of the closet and feed it regularly.
// We'll use it later on as a "snapshot" to verify against.
$clone = clone $original;

// No one cares about the second clone. I remember Dolly, but what came after?
$clone_two = clone $original;

// See, at this point, you wouldn't care, except that there's a comment here!
$clone_three = clone $original;
$clone_four = clone $original;

echo "testing that everything is the 'same'" . PHP_EOL;
$test['one'] = ($original == $clone);
$test['two'] = ($original == $clone_two);
$test['three'] = ($original == $clone_three);
$test['four'] = ($clone == $clone_two);
$test['five'] = ($clone == $clone_three);
$test['six'] = ($clone_two == $clone_three);
$test['seven'] = ($clone_four == $original);
$test['eight'] = ($clone_four == $clone_two);
$test['nine'] = ($clone_four == $clone_three);
var_dump(array_sum($test) == count($test));

/**
 * Make alterations to an object for investigative purposes.
 *
 * @param object $object
 *   The subject of our investigation. Pun totally intended.
 *
 * @return object
 *   Are we looking at copy or an altered original. Who knows?!
 */
function alter_original($object) {
  $object->property_one = 1;
  return $object;
}

/**
 * Make yet more alterations to an object for investigative purposes.
 *
 * @param object $object
 *   The subject of our investigation. Again, pun totally intended.
 *
 * @return object
 *   Are we looking at copy or an altered original. Who knows?!
 */
function alter_original_further($object) {
  $object->property_two = 2;
  return $object;
}

/**
 * Make idiotic alterations to an object for investigative purposes.
 *
 * @param object $object
 *   The subject of our investigation. Pun still intended, but regretted.
 *
 * @return object
 *   Are we looking at copy or an altered original. Who knows?!
 */
function alter_original_obscenely($object) {
  $lab_rat = alter_original($object);
  $lab_rat = alter_original_further($lab_rat);
  // Snip off the tail, tag the ear...or something equally identifying. One
  // would assume that a "copy" of $object ($lab_rat) wouldn't be affected by
  // an alteration to the "original" from the argument. Let's see!
  $object->property_three = 3;
  return $lab_rat;
}

/**
 * Make idiotic alterations to an object for investigative purposes.
 *
 * @param object $object
 *   The subject of our investigation. Pun still intended, but regretted.
 *
 * @return object
 *   Are we looking at copy or an altered original. Who knows?!
 */
function frankenstein_it(&$object) {
  $chimp = $object;
  $frank = alter_original($chimp);
  unset($object->property_one);
  $monster = &alter_original_further($frank);
  // Doctor! Put down the needle and thread, that's enough, now!
  // Move the object from one variable to the next, over and over again and toss
  // in a reference marker to make sure.
  $object->property_three = 3;
  return $monster;
}

echo "the original:" . PHP_EOL;
var_dump($original);

echo "alterations being made..." . PHP_EOL;
$expected_to_be_a_copy = alter_original($original);
var_dump($expected_to_be_a_copy);

echo "and now we find out if the original has been altered..." . PHP_EOL;
var_dump($original);

echo "testing anew that \$original == \$clone:" . PHP_EOL;
var_dump($original == $clone);

echo "...same things happen with running alter_original_further...skip to obscenities." . PHP_EOL;

$guinea_pig = alter_original_obscenely($clone_two);

echo "guinea pigs are cuter than lab rats, but not much, really:" . PHP_EOL;
var_dump($guinea_pig);

echo "for comparison, a peek at the clone no one cares about:" . PHP_EOL;
var_dump($clone_two);

echo "now, I think we all know what's going to happ...well, yeah, that makes sense, too:" . PHP_EOL;
var_dump($guinea_pig == $clone_two);

echo "Monster mash ... ok ... sorry - by now you probably understand the only reason they're here is to guide the eye, right?" . PHP_EOL;
$pa = frankenstein_it($clone_four);
var_dump($pa);

echo "And here...what's going on with 4?" . PHP_EOL;
var_dump($clone_four);

echo "The only way to separated a 'copy' from the original seems to be by forcing a refer...crap...clone." . PHP_EOL;
var_dump($clone_four == $pa);