callback.php

<?php
echo ">>> Usage:\n";
function do_it($callback) {
  return $callback(null, true);
}

$result = do_it(function($error, $result) {
  if ($error) {
    echo "Error!\n";
    return false;
  }
  echo "Success\n";
  return true;
});

var_dump($result);

echo "\n>>> Useful example:\n";
$myArray = array(1, 2, 3, 5, 8, 13, 21);

$output = array_map(function($item) {
  return $item * 2;
}, $myArray);

echo implode(", ", $output), "\n";

/* Output
 * ======
 *
 * php callback.php
 * >>> Usage:
 * Success
 * bool(true)
 *
 * >>> Useful example:
 * string(23) "2, 4, 6, 10, 16, 26, 42"
 * (clockwork) Ξ Development/Felveteli → vim callback.php
 * (clockwork) Ξ Development/Felveteli → php callback.php
 * >>> Usage:
 * Success
 * bool(true)
 *
 * >>> Useful example:
 * 2, 4, 6, 10, 16, 26, 42
 **/