On Tue, 12 Aug 2003 10:44:45 +1000, Chris Trengove wrote > The date iterators in Boost Date-Time appear to be designed to > support iteration forward in time, being modelled on the STL > InputIterator. However, at times it is convenient to iterate > backwards in time, and the temptation is just to use something like > > day_iterator ditr(date,-1); > ++ditr; > > that is; specify a negative "offset" as the optional construction parameter > which all four of the iterators provide.
Yep. This has come up several times before... > This works for all of the provided iterators except the > month_iterator, and it wouldn't be too difficult to make that one > work as well (by providing a subtract() method for the wrapping_int2 > template used in the implementation). Another user has submitted a change to me, that hasn't made it into the library, that performs the equivalent by modifying adjust_functors.hpp. Looking back on the history of the number of requests on this it looks like it should be a priority to officially support this option. Or perhaps, even better, to step up and support bi-directional or random access iterators. > Are there any other issues involved in providing this support for backwards > iteration? No, it appears not, but if you do this make sure to write some tests to be sure... Jeff _______________________________________________ Unsubscribe & other changes: http://lists.boost.org/mailman/listinfo.cgi/boost
