Function ToString

cpp/src/arrow/type.h:269–271

  bool operator!=(const TypeHolder& other) const { return !(*this == other); }

  std::string ToString(bool show_metadata = false) const {
    return this->type ? this->type->ToString(show_metadata) : "<NULLPTR>";
  }

  static std::string ToString(const std::vector<TypeHolder>&, bool show_metadata = false);