On Wed, 03 Sep 2003 17:09:08 -0400, Philip Miller wrote > David Abrahams wrote: > > > I'm trying to get a ptime relative to 1/1/1970, so I did: > > > > using namespace boost::date_time; > > ptime d; > > ... > > boost::posix_time::time_duration since_1970 = d - 1/Jan/1970; > > > > Error. > > > > Since it is a completely lossless conversion (like an upcast), I'd > > like to see boost::date -> boost::posix_time::ptime implicit > > conversions added. > > Can you elaborate on the problem? I, too, am doing lots of
I believe that Dave is asking for a non-explicit constructor for ptime from date. But he is also using an expression template extension to allow the 1/Jan/1970 to compile. > conversions between the boost::date_time library date, ptime, and > duration instances with the conventional unix/posix dawn of time, > 1/1/1970. To my knowledge (perhaps in ignorance), I have had no > problems using constructs similar to > > ptime time0( date(1970, 1, 1 ) ); > ptime t1; > ... > time_duration dt = t1 - time0; > > Is the problem that you want to do this with date instances and not time > instances? Exactly. > With regards to another posting you made, I also work to work with > in sub-second time precision and have had a problem understanding > the nuances of clock ticks/resolutions. As a simple user I have not > had many (if any) problems getting the library to do what I want, > given that my assumption that time_duration::fractional_seconds > returns microseconds is correct. If/when this assumption becomes > invalid (i.e., date_time changes its internal representation for > msvc or I work on a platform that uses nanoseconds for > fractional_seconds), then I will be in trouble and have to fix a few > places spots in my code. So, I would like to see a standard You control the resolution when you compile as described in the docs so there isn't a change from platform to platform unless you set up your makefiles differently between platforms. > time_duration accessor that returns microseconds rather than the > compile-time dependent fractional_seconds. I think what you want is really 'total_microseconds', right? hours, minutes, and seconds provide a 'normalized count' which is really for 'breakdown printing' (eg: 10:09:08). And presumably if your time_duration was using nanoseconds you might what total_microseconds to round up/down appropriately? Jeff _______________________________________________ Unsubscribe & other changes: http://lists.boost.org/mailman/listinfo.cgi/boost
