Re: [boost] boost::date_time: ISO compliant IO for periods/durations?

From: Richard Peters (r.a.peters_at_[hidden])
Date: 2004-05-12 04:07:25

----- Original Message ----- 
From: "Jeff Garland" <jeff_at_[hidden]>

> > conforming extractors/inserters for the duration/period
> > classes? Specifically I am looking for io/string functions which
> > can handle "Periods of Time, no Specific Start or End", which
> > begin with a 'P' following a list of periods, e.g.
> >
> > "P18Y9M4DT11H9M8S" (18 years, 9 months, 4 days, 11 hours,
> > 9 minutes and 8 seconds)
>
> I'm afraid the library doesn't currently offer an extraction of this sort
of
> duration.  The primary reason is that I (and others) have had difficulty
> dealing with the imprecise nature of a time duration that includes years
and
> months.  The problem is, what is the length of a duration such as '3
months'?
>  The answer is, it depends on which day you want to measure it from and
what
> rules you want to apply.  So for representing durations you currently only
> have days, hours, minutes, and seconds.

Such functionality would come very handy at times, though. Say you want
something to occur every first day of the month. You'd want a start date
which is the first day of a month, and increase that date with one month to
reach the next month. This is currently very difficult, because the next
date has to be calculated manually. It would be nice if a duration of a
month or a year was available, although comparing the length of a month and
the length of 30 days would be quite impossible.

best regards,

Richard Peters