Lessons learned from developing nccopy

25.2 Lessons learned from developing nccopy

Was anything useful learned in developing the generic netCDF program nccopy?

Development of nccopy did uncover some missing functionality that had been overlooked in designing the original netCDF-4 API, requiring several two new functions
- determining whether two user-defined types are equal
- determining the ID of a type from its name
Subsequent development of the nccopy utility for the netCDF-4 enhanced data model demonstrated the completeness and utility of the netCDF-4 API.
The nccopy4.c program required about twice as much code as nccopy3.c, providing an estimate for effort to adapt generic netCDF-3 software to handle netCDF-4:
```
  $ wc nccopy3.c nccopy4.c      # wc reports number of lines, words, characters
    493  1744 13273 nccopy3.c
    910  3367 26154 nccopy4.c
  
```
The nccopy development also revealed the need for some higher-level APIs to make generic netCDF software development easier, such as iterator interfaces.