Prefer enumerations over macros

Reason

Macros do not obey scope and type rules. Also, macro names are removed during preprocessing and so usually don't appear in tools like debuggers.

Example

First some bad old code:

// webcolors.h (third party header)
#define RED   0xFF0000
#define GREEN 0x00FF00
#define BLUE  0x0000FF

// productinfo.h
// The following define product subtypes based on color
#define RED    0
#define PURPLE 1
#define BLUE   2

int webby = BLUE;   // webby == 2; probably not what was desired

Instead use an enum:

enum class Web_color { red = 0xFF0000, green = 0x00FF00, blue = 0x0000FF };
enum class Product_info { red = 0, purple = 1, blue = 2 };

int webby = blue;   // error: be specific
Web_color webby = Web_color::blue;

We used an enum class to avoid name clashes.

Note

Also consider constexpr and const inline variables.

Enforcement

Flag macros that define integer values. Use enum or const inline or another non-macro alternative instead.