php-doc

Documentation (phpDoc)

Golden Rule

Never duplicate signature information without adding value. If the class name, method name, parameter names, and PHP types already tell the full story, skip the docblock entirely.

Skip documentation when:

• The method is trivial and self-explanatory (getters, setters, simple delegations)
• The docblock would only repeat what the signature already says
• Parameter names are descriptive enough ($width, $height, $name)

Write documentation when:

• The method has non-obvious behavior (returns null in specific conditions, throws exceptions)
• Array contents need specification (@return string[])
• Parameters have constraints, formats, or valid ranges not captured by PHP types
• The "why" behind a design choice matters for callers

Writing Style

• Be concise and direct - avoid unnecessary words
• Start method descriptions with 3rd person singular present tense verb: Returns, Formats, Checks, Creates, Converts, Sets
• Skip phrases like "Class that...", "Interface for...", "Method that..."
• Don't duplicate method lists or implementation details in class docblocks
• Use active phrasing describing main responsibility

Property Documentation

Use single-line format for simple @var annotations:

/** @var string[] */
private array $name;

Short comments for non-obvious properties:

/** for back compatibility */
protected Explorer $context;

Parameters and Return Values

• Prefer ?Type over Type|null for nullable types
• Only document parameters when adding information beyond PHP types
• Use two-space alignment for readability in multi-param blocks:

  /**
   * @return string  primary column sequence name
   * @param  mixed   $var  description here
   */
  

Include parameter docs only when explaining:

• Additional context or constraints
• Limitations or conditions
• Unusual usage patterns

Generic Array Types

Array key types

• array<T> = array<int|string, T> - any keys (omitting key type means int|string)
• array<int, T> - int keys only (not necessarily sequential)
• array<string, T> - string keys only
• list<T> - sequential int keys starting from 0 (0, 1, 2...)

Input vs output distinction

• @return: list<T> is accurate if the function always returns sequential keys
• @param: list<T> can be too restrictive - may reject valid inputs with non-sequential keys

When to use list<T> for input

Analyze the implementation:

• foreach ($arr as $v) - doesn't use keys → array<T> is sufficient
• $arr[0], $arr[1] - accesses by index → requires list<T>

Conditional return types

For return types dependent on parameters:

/**
 * @return ($flag is true ? list<array{string, int}> : list<string>)
 */

How to determine the correct type

1. Examine the implementation - how is the array used?
2. Write a test script that outputs the result structure if needed
3. For nested arrays, analyze each nesting level separately

Exception Documentation

• Use a single natural-language sentence describing the problem
• Avoid phrases like "Exception that is thrown when..."
• Use consistent phrases:
  • "does not exist" - for missing items
  • "failed to" - for operation failures
  • "cannot" - for impossible operations
  • "is not supported" - for unsupported features

Examples:

• "The file does not exist."
• "Cannot access the requested class property."
• "The value is outside the allowed range."
• "Failed to read from or write to a stream."

Examples

Good Documentation

Clear purpose, adding array contents info:

/**
 * Returns list of supported languages.
 * @return string[]  Array of language codes
 */
public function getSupportedLanguages(): array

Describing unusual behavior:

/**
 * Creates new transaction. Returns null if user has exceeded daily limit.
 */
public function createTransaction(float $amount): ?Transaction

When to Skip

// Signature says it all - no docblock needed
protected readonly string $name;

public function getWidth(): int

public function setName(string $name): void

Self-explanatory parameters - document only the method purpose:

/**
 * Calculates dimensions of image cutout.
 */
public function calculateCutout(int $left, int $top, int $width, int $height): array