Named Arguments, Defaults and Spread

Named arguments (8.0) let you pass values by parameter name, in any order, and skip optional parameters. They make calls with many booleans or options self-documenting. The spread operator ... unpacks arrays (including string keys, since 8.1) into arguments and collects variadic parameters.

<?php
// Self-documenting calls
$json = json_encode($data, flags: JSON_PRETTY_PRINT | JSON_THROW_ON_ERROR);
$html = htmlspecialchars($input, double_encode: false);

function createUser(string $email, string $role = 'member', bool $active = true): User { /* ... */ }
createUser('[email protected]', active: false);          // skip $role

// Spread with string keys maps to named arguments (8.1+)
$args = ['email' => '[email protected]', 'role' => 'admin'];
createUser(...$args);

function sum(int ...$numbers): int { return array_sum($numbers); }
echo sum(1, 2, 3);  // 6

Common pitfalls

• Parameter names become part of your public API — renaming a parameter can break callers using named arguments.
• Mixing positional arguments after named ones is a compile error.
• Passing an unknown named argument throws an Error.

Key points

• Named arguments make boolean/options calls readable
• Parameter names are now part of the API contract
• Spread unpacks arrays; string keys map to names

Further reading: PHP manual: named arguments