Writing Meaningful PHPDoc Annotations

Document non-obvious array shapes, generics and failure modes that PHP native types cannot fully express.

The objective is to understand the behavior and operational limits, not only the method name.

What It Does

Document non-obvious array shapes, generics and failure modes that PHP native types cannot fully express.

Prerequisites

Use a dedicated development environment and sample data. Where a snippet uses an injected connection, repository, request value or mailer, supply it from your own application setup.

Example 1: Basic Use

A focused working pattern for this topic. Names such as $pdo, $authContext and $repo represent dependencies provided by the application unless initialized in the snippet.

<?php
/** @param array<int, array{id:int, email:string}> $rows
 *  @return list<string>
 */
function emails(array $rows): array {
    return array_values(array_map(static fn(array $row): string => $row['email'], $rows));
}

Example 2: A Second Scenario

A second use case that adds a different operation or data flow specific to this topic.

<?php
/** @param non-empty-string $email @return array{local:string,domain:string} */
function splitEmail(string $email): array {
    [$local,$domain] = explode('@',$email,2);
    return ['local'=>$local,'domain'=>$domain];
}

Example 3: Practical Checks

A practical validation, failure or deployment concern specific to this topic.

<?php
/** @template T @param list<T> $items @return T|null */
function firstOrNull(array $items): mixed { return $items[0] ?? null; }
echo firstOrNull(['red','blue']);

Important Behavior and Edge Cases

PHPDoc is advisory metadata for tooling, not runtime validation.

For production use, also account for error handling, data validation, resource limits and environment-specific driver behavior.

Comparison with Related Approaches

Common Beginner Mistakes

Key Takeaways

• Document non-obvious array shapes, generics and failure modes that PHP native types cannot fully express.
• PHPDoc is advisory metadata for tooling, not runtime validation.
• Use this workflow as a focused starting point rather than a substitute for application-level tests.

Choose this API or pattern when its exact semantics match your task, and verify the result against the database driver and runtime used by your application.