A less useless recursive merge of arrays

custom_merge_recursive.php

<?php
/*
 * As you probably know array_merge_recursive() is pretty useless. This is a function
 * that I always tend to write when working with recursive merges of arrays.
 *
 * See output.txt to see the difference in behaviour.
 */

function custom_merge_recursive(/* $a, $b, $c, ... */) {
  $args = func_get_args();
  $a = array_shift($args);

  foreach ($args as $b) {
    foreach ($b as $key => $val) {
      if (is_array($val) && is_array($a[$key])) {
        $b[$key] = custom_merge_recursive($a[$key], $val);
      }
    }
    $a = array_merge($a, $b);
  }

  return $a;
}

$defaults = array(
  'pageOffset' => 0,
  'itemsPerPage' => 10,
  'filter' => array(
    'OrderBy' => 'None',
    'SortOrder' => 'Descending',
    'SubCategoryId' => 0,
  ),
);

echo "//-- Result with array_merge_recursive\n";
var_dump(array_merge_recursive($defaults, array(
    'pageOffset' => 2,
    'filter' => array(
      'SubCategoryId' => 10,
    ),
  ),
  array(
    'itemsPerPage' => 20,
  )));

echo "\n//-- Result with custom_merge_recursive\n";
var_dump(custom_merge_recursive($defaults, array(
    'pageOffset' => 2,
    'filter' => array(
      'SubCategoryId' => 10,
    ),
  ),
  array(
    'itemsPerPage' => 20,
  )));

output.txt

//-- Result with array_merge_recursive
array(3) {
  ["pageOffset"]=>
  array(2) {
    [0]=>
    int(0)
    [1]=>
    int(2)
  }
  ["itemsPerPage"]=>
  array(2) {
    [0]=>
    int(10)
    [1]=>
    int(20)
  }
  ["filter"]=>
  array(3) {
    ["OrderBy"]=>
    string(4) "None"
    ["SortOrder"]=>
    string(10) "Descending"
    ["SubCategoryId"]=>
    array(2) {
      [0]=>
      int(0)
      [1]=>
      int(10)
    }
  }
}

//-- Result with custom_merge_recursive
array(3) {
  ["pageOffset"]=>
  int(2)
  ["itemsPerPage"]=>
  int(20)
  ["filter"]=>
  array(3) {
    ["OrderBy"]=>
    string(4) "None"
    ["SortOrder"]=>
    string(10) "Descending"
    ["SubCategoryId"]=>
    int(10)
  }
}