cpp-rules

C++ Rules

These rules come from app/rules/cpp/ in ai-toolkit. They cover the project's standards for coding style, frameworks, patterns, security, and testing in C++. Apply them when writing or reviewing C++ code.

C++ Coding Style

Naming

• PascalCase: classes, structs, enums, type aliases, concepts.
• camelCase or snake_case: functions, methods, variables (be consistent per project).
• UPPER_SNAKE: macros, compile-time constants.
• Prefix member variables with m_ or suffix with _ (pick one convention).
• Namespace names: lowercase, short (namespace io, namespace util).

Modern C++ (17/20/23)

• Use auto for iterator types and complex template deductions.
• Use std::optional<T> instead of sentinel values or pointers for optional returns.
• Use std::variant over union types. Use std::visit for dispatch.
• Use std::string_view for non-owning string parameters.
• Use structured bindings: auto [key, value] = *map.begin();.
• Use constexpr for compile-time evaluation. Prefer over macros.

Memory Management

• Use RAII exclusively. Every resource acquisition is an initialization.
• Use std::unique_ptr for exclusive ownership (default choice).
• Use std::shared_ptr only when ownership is genuinely shared.
• Never use raw new/delete. Use std::make_unique / std::make_shared.
• Use std::span<T> (C++20) for non-owning views over contiguous data.

Functions

• Pass small types by value. Pass large types by const&.
• Use [[nodiscard]] on functions whose return value must not be ignored.
• Use noexcept on functions that do not throw (move constructors, destructors).
• Limit function parameters to 4. Use structs for configuration objects.
• Use trailing return types for complex template return deductions.

Includes and Dependencies

• Use #pragma once or include guards. Prefer #pragma once for simplicity.
• Order: corresponding header, C++ stdlib, third-party, project headers.
• Forward-declare in headers when possible to reduce compile times.
• Minimize header dependencies. Use the Pimpl idiom for ABI stability.