Documentation in PHP: How to Write Code That Speaks for Itself

Why is your PHP project doomed without documentation?

Imagine: you open a project you wrote six months ago. Tons of files, strange variable names, and worst of all — not a single comment. Sound familiar? Now imagine you need to hand this project over to a newbie on the team or, even worse, to a client. Without documentation, it turns into a "Guess what this method does" quest.

In the PHP community, there's an unwritten rule: good code is documented so that any Junior-level developer can understand it. And it's not about writing novels in comments. It's about a system that saves you hours of your life.

In this article, we'll break down the best practices for documenting PHP projects. You'll learn how to make your code speak for itself and make documentation useful, not a headache.

PHPDoc: Your Main Tool

Let's start with the basics. PHPDoc is the standard for annotating code in PHP. It is understood by most IDEs (PhpStorm, VS Code) and tools like phpDocumentor. If you're not using PHPDoc yet, you're wasting time deciphering your own code.

How to Properly Format PHPDoc Blocks

A basic template for a function or method looks like this:

/**\n * Brief description of what the function does.\n *\n * Detailed description (optional), if you need to explain complex logic.\n *\n * @param string $name The user's name.\n * @param int $age The user's age (optional).\n * @return string A greeting message.\n *\n * @throws \\InvalidArgumentException If the name is empty.\n */\nfunction greetUser(string $name, int $age = 0): string\n{\n    if (empty($name)) {\n        throw new \\InvalidArgumentException('Name cannot be empty');\n    }\n    \n    $greeting = "Hello, {$name}!";\n    if ($age > 0) {\n        $greeting .= " You are {$age} years old.";\n    }\n    \n    return $greeting;\n}

Key points:

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• @param — describes the type and purpose of each argument.
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• @return — specifies the return type and its meaning.
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• @throws — lists the exceptions the method may throw. This will save you from runtime surprises.
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Annotations for Class Properties

Properties also need to be documented. Especially if they have complex types:

class UserService\n{\n    /**\n     * User repository for working with the database.\n     *\n     * @var UserRepositoryInterface\n     */\n    private UserRepositoryInterface $userRepository;\n\n    /**\n     * Cache for storing search results.\n     *\n     * @var CacheInterface|null\n     */\n    private ?CacheInterface $cache = null;\n}

Note: we use @var to specify the type. Even if you have strict typing (PHP 7.4+), the annotation helps IDEs and static analyzers.

Common PHPDoc Mistakes (and How to Avoid Them)

Even experienced developers sometimes make blunders. Here are the most common ones:

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• Empty blocks: /** */ before a function is useless clutter. Either write something meaningful or delete it.
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• Outdated information: you changed the method signature but forgot to update the PHPDoc. The result — misinformation. Always synchronize documentation with code.
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• Redundancy: don't write @return string if it's obvious the function returns a string. PHPDoc should explain the meaning, not duplicate the type.
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README: The Face of Your Project

PHPDoc is internal documentation for developers. But README.md is what everyone sees: from colleagues to random GitHub visitors. A good README answers three questions:

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1. What is this? — a brief description of the project.
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2. How do I set it up? — installation instructions.
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