c++ - Sequence of enumerators at compile time

Question

Given a C++11 enum class, is there some templating or other construct to iterate, at compile-time, over the set of all enumerators? Could one define a template to e.g. initialize an array with all possible values of that enum type?

Answer 1

One alternative technique is to resort to the pre-processor.

#define ITERATE_MY_ENUM(_) 
  _(A,) 
  _(B, =3) 
  _(C,) 
  _(D, =10)

enum MyEnum {
  #define DEFINE_ENUM_VALUE(key, value) key value,

  ITERATE_MY_ENUM(DEFINE_ENUM_VALUE)

  #undef DEFINE_ENUM_VALUE
};

void foo() {
  MyEnum arr[] = {
    #define IN_ARRAY_VALUE(key, value) key,

    ITERATE_MY_ENUM(IN_ARRAY_VALUE)

    #udnef IN_ARRAY_VALUE
  };
}

Some may consider it ugly, but it still keeps the code DRY.