From: Jeff Garland (jeff_at_[hidden])
Date: 2003-08-19 08:49:31
On Tue, 19 Aug 2003 13:25:37 +1000, Chris Trengove wrote
> I have some concerns about the implementation of the "period"
> concept, as given in period.hpp. First of all, the documentation
> (for, say, date_period) talks of the constructor
>
> date_period(date begin,date last)
>
> as creating a period as [begin,last). But really what is meant here
> is that the "last" parameter is actually going to become the "end"
> of the period. This is clear from the implementation in period.hpp,
> which is
>
> template<class point_rep, class duration_rep>
> inline
> period<point_rep,duration_rep>::period(point_rep begin, point_rep
> end)
Yes, the function defintion is misleading. In the function implementation
(shown above) it is clear that this is the end.
> I think there are two errors in the implementation of the period
> class, perhaps caused by this confusion between "last" and "end".
>
> 1) is_null() is implemented as
>
> return last_ <= begin;
>
> which means that a period of length 1 is judged as being "null". The
> correct implementation should be
>
> return end() <= begin;
> or
> return last < begin;
Yep. Fixed in CVS.
> 2) operator<() is implemented as
>
> return (last_ <= rhs.begin_);
>
> and this should be
>
> return (end() <= rhs.begin_);
> or
> return (last_ < rhs.begin_);
Yep. Fixed in CVS.
> Also, I think that the implementation would be simpler and more
> efficient if _end was chosen as the data member, rather than _last.
>
> ... detail omitted...
Probably true, I'll put this on the todo list to look at.
Thanks for the detailed comments.
Jeff