Frank Laub wrote:
Currently, there are three flavors of enumerated types available.
1. BOOST_ENUM This type of enum provides the user with a simple way to express an enum.
example usage: BOOST_ENUM(boolean, (False) (True) )
This flavor does not allow each element of the enum to be defined. It is assumed that the first element will begin with the value 0 and the last element will be equal to the count of elements - 1. The following methods are available with this type:
static const_iterator begin() static const_iterator end() static boost::optional<const T> get(size_t index) static boost::optional<const T> parse(const char* str) const char* str() const bool operator == (const T& rhs) const bool operator != (const T& rhs) const ostream& operator << (ostream& os, const T& rhs)
1. What about constructors? 2. What happened to the static 'size' member? 3. The get() and parse() methods can return optional<T> rather than optional<const T>. Since everything here is copied-by-value, the const doesn't add much, IMO. 4. You also need operator< for set/map. 5. If you have parse() and operator<<, then I guess adding operator>> would be logical. 6. People would probably want a value() method as you put in BOOST_ENUM_VALUES, in here also.
2. BOOST_ENUM_VALUES This flavor of enum is the same as the basic enum flavor but it allows the user to specify values for each element.
example usage: BOOST_ENUM_VALUES(VirtualKey, (Space)(0x20) (Prior)(0x21) (Next)(0x22) (End)(0x23) (Home)(0x24) )
In addition to the methods described above with the basic flavor, these are also available:
static boost::optional<const T> make(size_t value) size_t value() const
As far as I know, C++ allows the numeric value of a enum to be negative, so instead of size_t (in both these functions), you need a signed type. I also think there would be some confusion between get() and make(). With BOOST_ENUM, get() is naturally the only choice. So users would be tempted to use get() also with BOOST_ENUM_VALUES. But this is probably not what they are after. With BOOST_ENUM_VALUES, make() is what is most useful, and IMO, get() is mostly useless. So maybe get() should do what make() does today, and the old get() functionality should be names get_by_index() or something similar.
As always, any comments are much appreciated.
All in all, great job! Yuval