Re: [boost] [chrono] time_point.hpp depends on Boost.System; should it?

Subject: Re: [boost] [chrono] time_point.hpp depends on Boost.System; should it?
From: Vicente J. Botet Escriba (vicente.botet_at_[hidden])
Date: 2012-06-27 13:51:22

Le 27/06/12 14:15, Krzysztof Czainski a écrit :
> Hello,
>
> I want to create my own clock class, and in it among other things I would
> like to typedef a time_point<...>.
>
> struct MyClock
> {
>      typedef int64_t rep;
>      typedef boost::milli period;
>      typedef boost::chrono::duration<rep,period>  duration;
>      typedef date_chrono::time_point<SystemClock,duration>  time_point;
I gues you mean chrono:: and not date::chrono::
>      static bool const is_monotonic = false;
is_monotonic is not used any more. You should use is_steady.
>      static time_point now();
> };
>
> Now, for this to work I obviously need to #include
> <boost/chrono/time_point.hpp>. Including it causes a dependency on
> Boost.System, making me have to link with it. But since I don't use any
> clocks provided by Boost.Chrono, I think the dependency on Boost.System is
> unnecessary.
 From the documentation
"

            Don't provide Hybrid Error Handling

When |BOOST_CHRONO_DONT_PROVIDE_HYBRID_ERROR_HANDLING| is defined the 
lib don't provides the hybrid error handling prototypes:

Clock::time_point  Clock::now(system::error_code&ec=boost::thows());

This allow to be closer to the standard and to avoid the Boost.System 
dependency, making possible to have Boost.Chrono as a header-only library."

Unfortunately, when this macro is defined the include to 
<boost/system/error_code.hpp> is yet done. I will fix it.

>
> In fact, I was able to get rid of the dependency, and everything seems to
> work. I commented out 1 line from<boost/chrono/time_point.hpp>:
> //#include<boost/chrono/detail/system.hpp>
>
> Could this #include be removed from time_point.hpp, or is it needed for
> something I am not using ATM?

See below.

Please, could you create a Trac ticket?

Best,
Vicente