- dimension_ = d.dimension_;
- dimension_callback_ = d.dimension_callback_;
- offset_ = d.offset_;
- offset_callbacks_ = d.offset_callbacks_;
- offsets_left_ = d.offsets_left_;
- parent_ = d.parent_;
+ offset_ = d.offset_ ? new Real (*d.offset_) : 0;
+ parent_ = d.parent_;
+ extent_ = d.extent_ ? new Interval (*d.extent_) : 0;