Better enums

This tip submitted by Brent on 2012-08-13 14:24:22. It has been viewed 476 times.
Rating of 0.0 with 0 votes

Rather than having the enum constants at the same scope as the enum itself, it's possible to nest them similar to C#.

Typical C++:
enum directions { up, down };

directions myDirection = up; //up is in global scope

Better:
NAMED_VALUES_TYPE( directions, { up, down } );

directions myDirection = directions::up; //up is nested

All you need is this gem:

#define NAMED_VALUES_TYPE(type_name, ...) \
struct type_name \
{ \
public: \
enum Values __VA_ARGS__ ; \
type_name() {} \
type_name(Values that) : value(that) { } \
Values operator =(Values that) { value = that; return that; } \
operator Values() const { return value; } \
bool operator ==(Values that) const { return value == that; } \
bool operator !=(Values that) const { return value != that; } \
bool operator ==(type_name that) const { return value == that.value; } \
bool operator !=(type_name that) const { return value != that.value; } \
private: \
Values value; \
}

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