Named Arguments (PHP 8.0)

Also Known As

TL;DR

Explanation

Named arguments (PHP 8.0+) allow calling functions with label: $value syntax, making long argument lists self-documenting and enabling skipping of optional parameters without passing null placeholders. For example, array_slice($array, offset: 2, preserve_keys: true) is clearer than array_slice($array, 2, null, true). They also work with built-in functions and constructors. Named arguments are positional-order-independent, but must come after positional arguments.

Common Misconception

Why It Matters

Common Mistakes

• Using named arguments for all calls — they are most valuable when skipping optional parameters or for clarity.
• Renaming function parameters without treating it as a breaking change — named argument callers break silently.
• Not using named arguments with built-in functions that have confusing parameter order — e.g., array_slice($arr, offset: 2, length: 5).
• Mixing positional and named arguments where the positional arguments come after named ones — PHP requires positional arguments first.

Code Examples

// Cryptic positional arguments:
$result = array_slice($users, 1, 5, true); // What does 'true' do here?

// Self-documenting with named arguments:
$result = array_slice($users, offset: 1, length: 5, preserve_keys: true);

// Before: cryptic positional arguments
$result = array_slice($array, 2, null, true);

// After: self-documenting with named args
$result = array_slice(array: $array, offset: 2, preserve_keys: true);

// Skip optional parameters you don't need
str_contains(haystack: $html, needle: '</body>');

// Named args in constructors — order doesn't matter
$req = new CreateUserRequest(
    email: 'alice@example.com',
    role:  'admin',
    name:  'Alice',
);

References

• ↗ https://www.php.net/manual/en/functions.arguments.php#functions.named-arguments

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