Boost C++ Libraries: Ticket #11631: boost chrono io v2 does not let you support custom clocks

attachment set

Wed, 09 Sep 2015 10:00:53 GMT

attachment → chrono_io_custom.tgz

status changed

viboes — Thu, 10 Sep 2015 06:05:16 GMT

status new → assigned

My bad. maybe the documentation is not explicit enough that this is not supported.

The reference states the possible customization points

  protected:
    virtual ~time_point_units();
    virtual string_type do_get_epoch(system_clock) const=0;
    virtual string_type do_get_epoch(steady_clock) const=0;
#if defined(BOOST_CHRONO_HAS_PROCESS_CLOCKS)
    virtual string_type do_get_epoch(process_real_cpu_clock) const=0;
    virtual string_type do_get_epoch(process_user_cpu_clock) const=0;
    virtual string_type do_get_epoch(process_system_cpu_clock) const=0;
    virtual string_type do_get_epoch(process_cpu_clock) const=0;
#endif
#if defined(BOOST_CHRONO_HAS_THREAD_CLOCK)
    virtual string_type do_get_epoch(thread_clock) const=0;
#endif}}}
I would need to type erase the clock in someway, but I don't know how the user could identify its clock.

milestone changed

viboes — Thu, 10 Sep 2015 17:47:11 GMT

milestone To Be Determined → Boost 1.60.0

I think that I have found a way the user can customize the Clock string. I don't know however how it can customize it depending on a specific locale.

The trick is to use an indirection

      template <typename Clock>
      string_type get_epoch() const
      {
        return get_epoch_custom<CharT>(Clock(), *this);
      }

where get_epoch_custom just forwards again to the facet.

    template <typename CharT, typename Clock, typename TPUFacet>
    std::basic_string<CharT> get_epoch_custom(Clock, TPUFacet& f)
    {
      return f.do_get_epoch(Clock());
    }

The user can specialize its onw Clock by overloading this customization function.

template <typename CharT, typename TPUFacet>
std::basic_string<CharT> get_epoch_custom(MyMillenniumClock, TPUFacet&)
{
  return boost::chrono::clock_string<MyMillenniumClock,CharT>::since();
}

Committed in master branch https://github.com/boostorg/chrono/commit/533851116fa2c3870e05d878a9cc9c82c4b93fa1

status changed; resolution set

viboes — Sun, 25 Oct 2015 23:52:37 GMT

status assigned → closed
resolution → fixed

https://github.com/boostorg/chrono/commit/621b6faaf19d5c0b5ffd0a313e696b81495316a4