enum_type

Smart enumerations.
A method of declaring enumerations that allow grouping within a structure. Avoids the problem of clashing names that can occur with standard enumerations. One way to think of the code is as a type with built-in constants and an optional conversion to a string.

Declaring the enumeration.

struct CompassDirection
{
  enum enum_type
  {
    North = 0,
    South = 180,
    East  = 90,
    West  = 270
  };

  DECLARE_ENUM_TYPE(CompassDirection, int)
  ENUM_TYPE(North, "North")
  ENUM_TYPE(South, "South")
  ENUM_TYPE(East,  "East")
  ENUM_TYPE(West,  "West")
  END_ENUM_TYPE
};

Using the enumeration.

CompassDirection direction;          // Default construction.

direction = CompassDirection::North; // Assignment from an enumeration constant;

int value = direction;               // Implicit conversion to 'int'.

direction = CompassDirection(value); // Explicit conversion from 'int'.

direction = CompassDirection(3);     // Explicit conversion from an invalid value. This unfortunately cannot be avoided. Caveat emptor!

direction = value;                   // **** Compilation error ****

std::cout << "Direction = " << direction.to_string(); // Prints "Direction = North"

If a conversion to a string is not required then the 'ENUM_TYPE' declaration may be omitted. In that case the to_string() function will return a "?". This will also be the case for any enumeration value that does not have an ENUM_TYPE entry.