Scoped Enumerations

• Since c++ 11, there is a new enumeration type.
• These are sometimes called enum classes
• It avoids namespace collision.
• But it requires an extra scoping operation.
• You can use a type other than int if you wish (but we will not)
• In Effective Modern C++ Scott Meyers says
  • Item 10: Prefer scoped enums to unscoped enums
  • Due to the reduction in namespace pollution.
  • And they are stronger typed.
• Syntax

  • enum struct|class identifier{identifier=[const expression], identifier[=const expression], ...}
    enum struct|class:type identifier{identifier=[const expression], identifier[=const expression], ...}
             

• example

  • 
    enum class ResultT:unsigned char {YELLOW_SIGN, TENTACLE, ELDER_SIGN,
                                                      CTHULHU, EYE, UNKNOWN};
             

• The changes
  • You must always use a scope operator when referencing one of the enumerators
  • ResultT i = ResultT::UNKNOWN;
  • Quite a few more casts.
    • But this is a good thing, you are forced to control the type.
• see die1.cpp
• You must use scoped enumeration types in my class.