# Firebase Cpp Commenting Standards

> Firebase C++ Commenting Standards

- Skill: `firebase/firebase-cpp-commenting-standards` (Agent Skill)
- Install (CLI): `npx skillmds@latest add firebase/firebase-cpp-commenting-standards`
- Raw SKILL.md: https://api.skillmd.com/api/skills/firebase/firebase-cpp-commenting-standards/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- Author: firebase (https://skillmd.com/u/firebase)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/firebase/firebase-cpp-commenting-standards

---

# Firebase C++ Commenting Standards

Guidelines for writing Doxygen documentation for C++ and Objective-C public APIs in the Firebase C++ SDK.

## Overview
All public-facing methods, classes, and properties should be documented using Doxygen-style triple-slash `///` or block comments `/** ... */`.

## C++ Standards

### 1. General Format
Use `///` for single-line or multi-line brief comments.
Use `@brief` to explicitly define the summary.

```cpp
/// @brief A brief description of the class or function.
```

### 2. Classes and Structs
Classes should have a summary of their purpose. Use `@see` for related links.

```cpp
/// @brief Options that control the creation of a Firebase App.
/// @if cpp_examples
/// @see firebase::App
/// @endif
class AppOptions { ... };
```

### 3. Methods and Functions
Always document parameters using `@param[in]` / `@param[out]` and return values using `@return` or `@returns`.

```cpp
/// @brief Load default options from the resource file.
///
/// @param options Options to populate from a resource file.
///
/// @return An instance containing the loaded options if successful.
static AppOptions* LoadDefault(AppOptions* options);
```

### 4. Conditional Documentation (SWIG/Unity)
For Unity/C# bindings, use `<SWIG>` tags and `@if swig_examples`. These are parsed by the SWIG commenting pipeline and ignored by the standard C++ Doxyfile.

```cpp
/// @if cpp_examples
/// To create a firebase::App object, the Firebase application identifier
/// and API key should be set using set_app_id() and set_api_key()
/// respectively.
/// @endif
/// <SWIG>
/// @if swig_examples
/// To create a FirebaseApp object, the Firebase application identifier
/// and API key should be set using AppId and ApiKey respectively.
/// @endif
/// </SWIG>
```

---

## Objective-C and iOS/tvOS Standards

Objective-C wrappers should also follow standard Doxygen conventions, especially if they are used to bridge to C++.

### 1. Class Properties

```objc
/// @brief The App ID of the Firebase App.
@property(nonatomic, readonly) NSString *appID;
```

---

## Checklist
- [ ] Are you using `///` for public API comments?
- [ ] Do you have a `@brief` for the method?
- [ ] Are all parameters documented with `@param`?
- [ ] Is the return value documented with `@return`?
- [ ] Are you using `<SWIG>` tags if the documentation needs to differ for Unity/C#?