----Original Message---- From: boost-bounces@lists.boost.org [mailto:boost-bounces@lists.boost.org] On Behalf Of Andy Little Sent: 08 June 2006 17:46 To: boost@lists.boost.org Subject: Re: [boost] [review] pqs
Although liter is equivalent to 1 dm^3, technically its not an SI unit. Its not in the review version of PQS, but it is possible to add a liter unit to volume header and get output as
1 L
or whatever is preferred... I just did this in my local version of PQS.
The sequence of steps is
1) In <boost/pqs/meta/components/of_volume.hpp>
Add a typedef for the liter in the incoherent_unit struct (starts at line 47). [SNIP]
That is not good. Not good at all. As far as I am concerned, a third party library file is (almost) sacrosanct. I would not want to edit it except to fix the most extreme bug - what happens when I upgrade to the next version of PQS. Can I add liter support externally to PQS? (For example, so I can refer to "litre").
typedef meta::unit< boost::pqs::meta::rational<-3>, meta::rational<1>::type, boost::mpl::int_<1> > liter;
2)
In <boost/pqs/t1_quantity/types/volume.hpp>
Add the typedef for liter to the other member typedefs:
typedef t1_quantity< type, typename incoherent_unit::liter, Value_type > liter;
3) In <boost/pqs/t1_quantity/types/out/volume.hpp> add the stream output overload for the liter unit:
inline std::ostream& operator <<( std::ostream & os, t1_quantity_units_out< meta::components::of_volume::type, meta::components::of_volume::incoherent_unit::liter > ) { os << "L"; return os; }
Check it works:
#include <boost/pqs/t1_quantity/types/out/volume.hpp> using boost::pqs::volume;
int main() { volume::liter v(1); std::cout << v <<'\n'; volume::m3 v1 = v; std::cout << v1 <<'\n'; }
Outputs:
1 L 0.001 m3
Because liter isnt an SI unit you would need to add cL and mL in the same way (I guess that would be the next question!)
regards Andy Little
-- Martin Bonner Martin.Bonner@Pitechnology.com Pi Technology, Milton Hall, Ely Road, Milton, Cambridge, CB4 6WZ, ENGLAND Tel: +44 (0)1223 203894