Testing "array soft-copy" in PHP5.6

_script.php

<?php

$byValue = function (array $value) {
  $z = $value[2];
};

$byValueWrite = function (array $value) {
  $value[] = 1;
  array_pop($value);
};

$byValueForeach = function (array $value) {
  foreach ($value as $i){}
};

$byValueForeachWrite = function (array $value) {
  foreach ($value as $i){}
  $value[] = 1;
  array_pop($value);
};

$byReference = function (array &$referenced) {
  $z = $referenced[2];
};

$byReferenceWrite = function (array &$referenced) {
  foreach ($referenced as $i) {}
  $referenced[] = 1;
  array_pop($referenced);
};

$byReferenceForeach = function(array &$referenced) {
  foreach ($referenced as $i){}
};

$byReferenceForeachWrite = function(array &$referenced) {
  foreach ($referenced as $i){}
  $referenced[] = 1;
  array_pop($referenced);
};


function measure($closure, $id) {
  $start = microtime(true);
  $arr = range(1, 10000);
  for ($i = 0; $i < 10000; $i++) {
    $closure($arr);
  }

  $total = round(microtime(true) - $start, 5);

  echo str_pad("Finished $id in", 50, '.') . "$total\n";
}


measure($byValue, 'by value');
measure($byReference, 'by reference');

measure($byValueWrite, 'by value write');
measure($byReferenceWrite, 'by reference write');


measure($byValueForeach, 'by value foreach');
measure($byReferenceForeach, 'by reference foreach');

measure($byValueForeachWrite, 'by value foreach write');
measure($byReferenceForeachWrite, 'by reference foreach write');

output

$ php ../test.php
Finished by value in..............................0.03721
Finished by reference in..........................0.0364
Finished by value write in........................4.97441
Finished by reference write in....................4.90189
Finished by value foreach in......................9.11332
Finished by reference foreach in..................4.1678
Finished by value foreach write in................14.68635
Finished by reference foreach write in............4.3133