[boost] Add macros for the "enum class" concept?

Subject: [boost] Add macros for the "enum class" concept?
From: Daryle Walker (darylew_at_[hidden])
Date: 2011-12-12 07:46:13

Should we add preprocessor stuff to conditionally use the C++11 "enum class" construct?

#if Whatever
#define BOOST_HAVE_ENUM_CLASS
#endif

//...

#if BOOST_HAVE_ENUM_CLASS
#define BOOST_ENUM_CLASS( Name )  enum class Name
#define BOOST_ENUM_CLASS_BASE( Name, Type )  enum class Name : Type
#define BOOST_ENUM_CLASS_REFER( Type, Enumerator )  (Type :: Enumerator)
#else
#define BOOST_ENUM_CLASS( Name )  enum Name
#define BOOST_ENUM_CLASS_BASE( Name, Type )  BOOST_ENUM_CLASS( Name )
#define BOOST_ENUM_CLASS_REFER( Type, Enumerator )  (Enumerator)
#endif

I'm not sure that the second version of BOOST_ENUM_CLASS_BASE is the best alternative.  Nor do I know if the parentheses around enumerators are best.

You can use BOOST_ENUM_CLASS in an enum definition header and BOOST_ENUM_CLASS_BASE as a header or a forward declaration.  Since enumerators can be scoped, BOOST_ENUM_CLASS_REFER encapsulates the need to add the enum type's name.