Implementation of array_column function for PHP 5.3+, support for array of objects is also provided.

arrayColumn.php

<?php

/**
 * Implementation of array_column function for PHP 5.3+, support for array of objects is also provided.
 *
 * @param array $input
 * @param mixed $column_key
 * @param mixed $index_key
 * @return array
 * @see http://php.net/manual/en/function.array-column.php
 */
function arrayColumn($input, $column_key, $index_key = null)
{
    if (func_num_args() < 2) {
        trigger_error('array_column() expects at least 2 parameters, '.func_num_args().' given', E_USER_WARNING);

        return null;
    } elseif (!is_array($input)) {
        trigger_error('array_column() expects parameter 1 to be array, '.gettype($input).' given', E_USER_WARNING);

        return null;
    }

    if ($index_key) {
        return array_combine(
            arrayColumn($input, $index_key),
            arrayColumn($input, $column_key)
        );
    }

    // If an array of objects is provided, then public properties can be directly pulled.
    // In order for protected or private properties to be pulled, the class must implement both the
    // __get() and __isset() magic methods.
    foreach ($input as $key => $val) {
        if (is_object($val) && !in_array($column_key, get_object_vars($val)) &&
            (!method_exists($val, '__get') || !method_exists($val, '__isset'))) {
            unset($input[$key]);
        }
    }
    
    $input_count = count($input);

    return array_map(
        function ($element, $column_name) {
            if (is_object($element)) {
                return $element->{$column_name};
            }

            return $element[$column_name];
        },
        $input,
        $input_count ? array_fill(0, $input_count, $column_key) : array()
    );
}