C++ code:

// In a header file that gets included by basically everything
enum class SomeEnum
{
  ThingOne,
  ThingTwo,
  ThingThree,
  ThingFour,
// etc
  ThingThirty,
};

// ELSEWHERE
class EnumMaps // Oh no
{
public:
  static EnumMaps& instance(); // Pisssssss
  std::map<SomeEnum, size_t>& some_enum_to_index_map(); // Maybe there's a reason for this?
  std::map<size_t, SomeEnum>& index_to_some_enum_map(); // Like the indexes don't match up with the enum values for some reason so this made sense at some point?
private:
  EnumMaps();
  std::map<SomeEnum, size_t> _some_enum_to_index_map {
    { SomeEnum::ThingOne, 0}, // Like maybe there are some gaps in it for legacy reasons and
    // ...
    { SomeEnum::ThingThirty, 29} // gently caress
  }
  std::map<size_t, SomeEnum> _index_to_some_enum_map { // please no
    { 0, SomeEnum::ThingOne }, 
  // ...
    { 29, SomeEnum::ThingThirty}
  }
};