PHP named params

NamedParams.php

<?php
namespace Util;

/**
 * Workaround to avoid long unnamed argument list
 *
 * Usage:
 *
 * 1. Required params
 *
 *     extract(
 *     	   NamedParams::assert(['name1', 'name2'],
 *     	   $params
 *     );
 *
 * 2. Optional params (with default values)
 *
 *     extract(
 *     	   NamedParams::assert(['name3', 'name4' => 'defaultValue'],
 *     	   $params
 *     );
 *
 *  3. Type hinting
 *
 *     extract(
 *         NamedParams::assert(['name5' => ['type' => 'array'], 'name6' => ['type' => Connection::class]]),
 *         $params
 *     );
 *
 *     Type can be class name or type name (as returned by gettype() call)
 *
 *  4. Type hinting and optional params together
 *
 *     extract(
 *         NamedParams::assert(['name7' => ['type' => 'integer', 'defaultValue' => 5]]),
 *         $params
 *     );
 *
 */
class NamedParams
{
    /**
     * @param array $expectedParams
     * @param array $inputParams
     */
    public static function assert(array $expectedParams, array $inputParams)
    {
        // normalize to: param_name => [type => ..., defaultValue => ...]
        $normalizedExpectedParams = [];
        foreach ($expectedParams as $key => $val) {
            // already array, nothing to do
            if (is_array($val)) {
                $normalizedExpectedParams[$key] = $val;
                continue;
            }

            // 'name' => val
            if (!is_int($key)) {
                $normalizedExpectedParams[$key] = ['defaultValue' => $val];
                continue;
            }

            // 'name'
            $normalizedExpectedParams[$val] = [];
        }

        $redundantParams = array_diff_key($inputParams, $normalizedExpectedParams);
        if (!empty($redundantParams)) {
            throw new \InvalidArgumentException(sprintf('redundant params: %s', implode(', ', $redundantParams)));
        }

        $outputParams = [];

        foreach ($normalizedExpectedParams as $key => $val) {
            if (array_key_exists($key, $inputParams)) {
                if (isset($val['type'])) {
                    $isValidInstance = ($inputParams[$key] instanceof $val['type']);
                    $isValidScalarType = (gettype($inputParams[$key]) == $val['type']);

                    if (!$isValidInstance && !$isValidScalarType) {
                        throw new \InvalidArgumentException(
                            sprintf('invalid type, %s param should be %s', $key, $val['type'])
                        );
                    }
                }

                $outputParams[$key] = $inputParams[$key];
                continue;
            }

            if (array_key_exists('defaultValue', $val)) {
                $outputParams[$key] = $val['defaultValue'];
                continue;
            }

            throw new \InvalidArgumentException(sprintf('missing param: %s', $key));
        }

        return $outputParams;
    }
}