Request for Comments: array_delete() for elements deletion

• Version: 0.3
• Date: 2012-08-21
• Author: Rasmus Schultz rasmus@mindplay.dk
• Status: Under Discussion
• First Published at: http://wiki.php.net/rfc/array_delete

This RFC proposes the addition of a set of two new functions that simplify working with arrays containing a set of unique values or objects that do not have any natural (or distinct) scalar keys that can be used as indices.

While the array-type in PHP does not support set-semantics, these functions simplify working with a set of unique values or objects stored in an array.

The first function simplifies removal of a value from an array, when the index is not known:

int array_delete(&$array, $value, $strict = TRUE)

The function is “destructive”, in the sense that it modifies the array in-place - for non-destructive removal, use array_filter().

The int return-value indicates number of removed elements.

To clarify how this function works, here is the PHP equivalent function:

function array_delete(&$array, $value, $strict = TRUE) {
    $count = 0;
    if ($strict) {
        foreach ($array as $key => $item) {
            if ($item === $value) {
                $count++;
                unset($array[$key]);
            }
        }
    } else {
        foreach ($array as $key => $item) {
            if ($item == $value) {
                $count++;
                unset($array[$key]);
            }
        }
    }
    return $count;    
}

If the same value occurs more than once in the given array, all occurrences of the given value will be deleted.

To prevent accidental deletion, $strict defaults to true - note that this differs from array_search() where the most likely objective is to “find something”.

int array_delete_recursive(&$array, $value, $strict = TRUE)

Recursive variant.

int array_udelete(&$array, callable $callable)

$callable takes 2 parameters, ($value, $key) When callable returns true, element is deleted.

int array_udelete_recursive(&$array, callable $callable)

Recursive variant.

To complement the array_delete() function, in terms of working with a set of unique values, a second function is proposed:

int array_add(&$array, $value, $strict = TRUE)

This function is “destructive”, like it's counterpart - for non-destructive addition, use array_merge().

The boolean return-value indicates whether or not the specified value was not already present and was added.

To clarify how this function works, here is the PHP equivalent function:

function array_add(&$array, $value, $strict = TRUE) {
  if (false === array_search($value, $array, $strict)) {
    $array[] = $value;
    return true;
  }
  return false;
}

To prevent accidentally adding duplicates, $strict defaults to true - this is consistent with array_delete().

These functions allow you to have set-like behavior but without performance benefits traditionally associated with a set.

The array_udelete function is practically identical to array_filter. The difference is that array_udelete would modify the function in-place and array_filter would not. Is it really that hard/unnecessary to reassign the result of array_filter back to the array?

No patch yet.

• PHP Internals discussion - http://www.serverphorums.com/read.php?7,546905
• Stack Overflow answers - http://stackoverflow.com/questions/7225070/php-array-delete-by-value-not-key

• 0.1 Initial version 2012/08/21
• 0.2 Changed to Rasmus' gist version 2012/08/21
• 0.3 Changed to array_delete() to have callable and return int. Added array_delete_recursive().
• 0.4 Reverted callable changes.