method comparison_function col =
match col with
| 1 -> fun ci1 -> fun ci2 ->
compare (string_of_status ci1.cvs_status) (string_of_status ci2.cvs_status)
| 2 -> fun ci1 -> fun ci2 ->
compare ci1.cvs_work_rev ci2.cvs_work_rev
| 3 -> fun ci1 -> fun ci2 ->
compare ci1.cvs_rep_rev ci2.cvs_rep_rev
| 4 -> fun ci1 -> fun ci2 ->
compare ci1.cvs_date_string ci2.cvs_date_string
| _ -> fun ci1 -> fun ci2 ->
compare ci1.cvs_file ci2.cvs_file