*******************
.h
class DamageClass {
public:
  enum Type { Unknown, Physical, Chemical, Electrical, Fire, Count };

  static unordered_map<string, Type> Names;
private:
  Type mValue{Unknown};

public:
  DamageClass() {
  }
  DamageClass(const string &str) {
    auto iter = Names.find(str);
    if (iter == Names.end()) {
      throw runtime_error("Invalid damage class: " + str);
    }
    mValue = iter->second;
  }
  DamageClass(const Type &type) : mValue(type) {
  }
  bool operator==(const Type &other) const {
    return mValue == other;
  }
  bool operator==(const DamageClass &other) const {
    return mValue == other.mValue;
  }
  operator Type() const {
    return mValue;
  }
  void Serialize(Serializer &sav) {
    sav &mValue;
  }
};

*****************
.cpp

#define ENTRY(x) {#x, x}

unordered_map<string, DamageClass::Type> DamageClass::Names = {
  ENTRY(Unknown),
  ENTRY(Physical),
  ENTRY(Chemical),
  ENTRY(Electrical),
  ENTRY(Fire),
  ENTRY(Count)
};