cpp-programming-guidelines

C++ Programming Guidelines

Basic Principles

• Use English for all code and documentation.
• Always declare the type of each variable and function (parameters and return value).
• Create necessary types and classes.
• Use Doxygen style comments to document public classes and methods.
• Don't leave blank lines within a function.
• Follow the one-definition rule (ODR).

Nomenclature

• Use PascalCase for classes and structures.
• Use camelCase for variables, functions, and methods.
• Use ALL_CAPS for constants and macros.
• Use snake_case for file and directory names.
• Use UPPERCASE for environment variables.
• Avoid magic numbers and define constants.
• Start each function with a verb.
• Use verbs for boolean variables. Example: isLoading, hasError, canDelete, etc.
• Use complete words instead of abbreviations and ensure correct spelling.
  • Except for standard abbreviations like API, URL, etc.
  • Except for well-known abbreviations:
  • i, j, k for loops
  • err for errors
  • ctx for contexts
  • req, res for request/response parameters

Functions

• Write short functions with a single purpose. Less than 20 instructions.
• Name functions with a verb and something else.
• If it returns a boolean, use isX or hasX, canX, etc.
• If it doesn't return anything (void), use executeX or saveX, etc.
• Avoid nesting blocks by:
  • Early checks and returns.
  • Extraction to utility functions.
• Use standard library algorithms (std::for_each, std::transform, std::find, etc.) to avoid function nesting.
• Use lambda functions for simple operations.
• Use named functions for non-simple operations.
• Use default parameter values instead of checking for null or nullptr.
• Reduce function parameters using structs or classes
  • Use an object to pass multiple parameters.
  • Use an object to return multiple results.
  • Declare necessary types for input arguments and output.
• Use a single level of abstraction.

Data

• Don't abuse primitive types and encapsulate data in composite types.
• Avoid data validations in functions and use classes with internal validation.
• Prefer immutability for data.
• Use const for data that doesn't change.
• Use constexpr for compile-time constants.
• Use std::optional for possibly null values.

Classes

• Follow SOLID principles.
• Prefer composition over inheritance.
• Declare interfaces as abstract classes or concepts.
• Write small classes with a single purpose.
  • Less than 200 instructions.
  • Less than 10 public methods.
  • Less than 10 properties.
• Use the Rule of Five (or Rule of Zero) for resource management.
• Make member variables private and provide getters/setters where necessary.
• Use const-correctness for member functions.

Exceptions

• Use exceptions to handle errors you don't expect.
• If you catch an exception, it should be to:
  • Fix an expected problem.
  • Add context.
  • Otherwise, use a global handler.
• Use std::optional, std::expected, or error codes for expected failures.

Memory Management

• Prefer smart pointers (std::unique_ptr, std::shared_ptr) over raw pointers.
• Use RAII (Resource Acquisition Is Initialization) principles.
• Avoid memory leaks by proper resource management.
• Use std::vector and other standard containers instead of C-style arrays.

Testing

• Follow the Arrange-Act-Assert convention for tests.
• Name test variables clearly.
• Follow the convention: inputX, mockX, actualX, expectedX, etc.
• Write unit tests for each public function.
• Use test doubles to simulate dependencies.
  • Except for third-party dependencies that are not expensive to execute.
• Write integration tests for each module.
• Follow the Given-When-Then convention.

Project Structure

• Use modular architecture
• Organize code into logical directories:
  • include/ for header files
  • src/ for source files
  • test/ for test files
  • lib/ for libraries
  • doc/ for documentation
• Use CMake or similar build system.
• Separate interface (.h) from implementation (.cpp).
• Use namespaces to organize code logically.
• Create a core namespace for foundational components.
• Create a utils namespace for utility functions.

Standard Library

• Use the C++ Standard Library whenever possible.
• Prefer std::string over C-style strings.
• Use std::vector, std::map, std::unordered_map, etc. for collections.
• Use std::optional, std::variant, std::any for modern type safety.
• Use std::filesystem for file operations.
• Use std::chrono for time-related operations.

Concurrency

• Use std::thread, std::mutex, std::lock_guard for thread safety.
• Prefer task-based parallelism over thread-based parallelism.
• Use std::atomic for atomic operations.
• Avoid data races by proper synchronization.
• Use thread-safe data structures when necessary.