loliGothicK/nameof

Nameof operator for modern C++

Nameof C++

 _   _                             __    _____
| \ | |                           / _|  / ____|_     _
|  \| | __ _ _ __ ___   ___  ___ | |_  | |   _| |_ _| |_
| . ` |/ _` | '_ ` _ \ / _ \/ _ \|  _| | |  |_   _|_   _|
| |\  | (_| | | | | | |  __/ (_) | |   | |____|_|   |_|
|_| \_|\__,_|_| |_| |_|\___|\___/|_|    \_____|

What is Nameof?

Header-only C++17 library provides nameof macros and functions to obtain simple name of variable, type, function, macro, and enum.

Features

• C++17
• Header-only
• Dependency-free
• Compile-time
• Name of variable, member variable
• Name of type, variable type
• Name of function, member function
• Name of enum, enum variable
• Name of macro
• Enum to string

Examples

• Nameof

  // Name of variable.
  NAMEOF(somevar) -> "somevar"
  
  // Name of member variable.
  NAMEOF(person.address.zip_code) -> "zip_code"
  
  // Name of function.
  NAMEOF(foo<int, float>()) -> "foo"
  
  // Name of member function.
  NAMEOF(somevar.some_method()) -> "some_method"
  NAMEOF(somevar.some_method<int>()) -> "some_method"
  
  // Name of macro.
  NAMEOF(__LINE__) -> "__LINE__"
  NAMEOF(NAMEOF(structvar)) -> "NAMEOF"

• Nameof enum

  auto color = Color::RED;
  // Name of enum variable.
  NAMEOF_ENUM(color) -> "RED"
  nameof::nameof_enum(color) -> "RED"

• Nameof type

  using T = int;
  T var = 42;
  // Name of variable type.
  NAMEOF_VAR_TYPE(var) -> "int"
  nameof::nameof_type<decltype(var)>() -> "int"
  
  // Name of type.
  NAMEOF_TYPE(T) -> "int"
  nameof::nameof_type<T>() -> "int"

• Compile-time

  constexpr auto somevar_name = NAMEOF(somevar);
  // somevar_name -> "somevar"
  constexpr auto color_name = NAMEOF_ENUM(Color::BLUE); // or nameof::nameof_enum(Color::BLUE)
  // color_name -> "BLUE"
  constexpr auto var_type_name = NAMEOF_VAR_TYPE(var); // or nameof::nameof_type<decltype(var)>()
  // var_type_name -> "int"
  constexpr auto type_name = NAMEOF_TYPE(T); // or nameof::nameof_type<T>()
  // type_name -> "int"

Remarks

• Nameof returns std::string_view. If argument does not have name, returns empty string.

• Nameof expression argument are identified, but do not evaluated.

• Nameof type returns compiler-specific type name.

• If you need name with template suffix, use NAMEOF_FULL.

  // Full name of template function.
  NAMEOF_FULL(foo<int, float>()) -> "foo<int, float>"
  
  // Full name of template member function.
  NAMEOF_FULL(somevar.some_method<int>()) -> "some_method<int>"

• If you need raw fully-qualified name, use NAMEOF_RAW.

  NAMEOF_RAW(::somevar.somefield) -> "::somevar.somefield"
  NAMEOF_RAW(&some_class::some_method<int>) -> "&some_class::some_method<int>"

• Enum value must be in range [NAMEOF_ENUM_RANGE_MIN, NAMEOF_ENUM_RANGE_MAX]. By default NAMEOF_ENUM_RANGE_MIN = -128, NAMEOF_ENUM_RANGE_MAX = 128.

  If need another range for all enum types by default, redefine the macro NAMEOF_ENUM_RANGE_MIN and NAMEOF_ENUM_RANGE_MAX.

  #define NAMEOF_ENUM_RANGE_MIN 0
  #define NAMEOF_ENUM_RANGE_MAX 256
  #include <nameof.hpp>

  If need another range for specific enum type, add specialization enum_range for necessary enum type.

  #include <nameof.hpp>
  
  enum number { one = 100, two = 200, three = 300 };
  
  namespace nameof {
  template <>
  struct enum_range<number> {
    static constexpr int min = 100;
    static constexpr int max = 300;
  };
  }

• Nameof enum obtains the first defined value enums, and won't work if value are aliased.

  enum ShapeKind {
    ConvexBegin = 0,
    Box = 0, // Won't work.
    Sphere = 1,
    ConvexEnd = 2,
    Donut = 2, // Won't work too.
    Banana = 3,
    COUNT = 4,
  };
  // NAMEOF_ENUM(ShapeKind::Box) -> "ConvexBegin"
  // nameof::nameof_enum(ShapeKind::Box) -> "ConvexBegin"

  Work around the issue:

  enum ShapeKind {
    // Convex shapes, see ConvexBegin and ConvexEnd below.
    Box = 0,
    Sphere = 1,
  
    // Non-convex shapes.
    Donut = 2,
    Banana = 3,
  
    COUNT = Banana + 1,
  
    // Non-reflected aliases.
    ConvexBegin = Box,
    ConvexEnd = Sphere + 1,
  };
  // NAMEOF_ENUM(ShapeKind::Box) -> "Box"
  // nameof::nameof_enum(ShapeKind::Box) -> "Box"
  
  // Non-reflected aliases.
  // NAMEOF_ENUM(ShapeKind::ConvexBegin) -> "Box"
  // nameof::nameof_enum(ShapeKind::ConvexBegin) -> "Box"

Integration

You should add required file nameof.hpp.

Compiler compatibility

• Clang/LLVM >= 5
• Visual C++ >= 15.3 / Visual Studio >= 2017
• Xcode >= 9
• GCC >= 7 (GCC >= 9 for NAMEOF_ENUM)

Licensed under the MIT License