PHP Named Arguments: Compatibility and Maintenance

Maintaining named-argument APIs requires stable public parameter names and defaults.

What It Does

Maintaining named-argument APIs requires stable public parameter names and defaults. The following examples distinguish a normal use case, a boundary case and a practical application.

Requirements and Compatibility

PHP 8.x and a local test environment. Apply input validation, correct error handling and the requirements of any optional libraries.

The code focuses on the core concept. Production implementation may also need routes, validation, persistence, authorization or deployment tooling.

Example 1: Basic Behavior

Start with the smallest meaningful working case.

<?php
function limitPage(int $page, int $size = 20): int { return ($page - 1) * $size; }
echo limitPage(size: 10, page: 3);

Example 2: Another Case

Examine the edge case and the observable result.

<?php
function fetchSlice(int $offset, int $limit): string { return "$offset:$limit"; }
try { echo fetchSlice(start: 0, limit: 20); } catch (Error $e) { echo 'Renamed parameter breaks named callers'; }

Practical Example: Putting It to Use

Parameter names become part of a public named-argument API.

<?php
function pageSlice(int $offset, int $length = 50): array { return [$offset, $length]; }
print_r(pageSlice(length: 10, offset: 30));
// Changing the parameter name length would break named callers.

Important Behavior and Edge Cases

Renaming a parameter can throw an unknown-named-parameter Error.

Comparison with Related Functions or Approaches

Common Beginner Mistakes

Key Takeaways

• Maintaining named-argument APIs requires stable public parameter names and defaults.
• Renaming a parameter can throw an unknown-named-parameter Error.
• Named parameters improve clarity when used with stable, intentionally documented names.

Before adapting these examples, verify the return values, test the failure paths and confirm that your application meets its security and environment requirements.