Method FromStringImpl

cpp/src/arrow/util/reflection_test.cc:77–81

struct FromStringImpl {
  template <typename Properties>
  FromStringImpl(std::string_view class_name, std::string_view repr,
                 const Properties& props) {
    Init(class_name, repr, props.size());
    props.ForEach(*this);
  }

  void Fail() { obj_ = std::nullopt; }