AMDG Matthias Schabel <boost <at> schabel-family.org> writes:
- Please don't call the units used in the U.S. "English" units. Here in England, we use the S.I. system for everything except pints of beer and miles on roadsigns. The units that we did use here until about 50 years ago were not the same as the ones that the Americans use.
In boost/units/systems/other/non_si_units.hpp I have included conversion factors for Imperial units (the ones used in the recent past in England), US Customary units, US Survey units, nautical units, some non-SI metric units, etc... English units generally refer to heterogeneous and obsolete units, while Imperial and US Customary are the main non-SI systems still in some use... See here, also :
We could define the base units separately and then mix and match struct meter_tag : public ordinal<1> {}; struct foot_tag : public ordinal<2> {}; struct inch_tag : public ordinal<3> {}; struct yard_tag : public ordinal<4> {}; struct mile_tag : public ordinal<5> {}; struct gram_tag : public ordinal<6> {}; struct slug_tag : public ordinal<7> {}; struct second_tag : public ordinal<8> {}; struct minute_tag : public ordinal<9> {}; struct hour_tag : public ordinal<10> {}; struct ampere_tag : public ordinal<11> {}; struct biot_tag : public ordinal<12> {}; struct kelvin_tag : public ordinal<13> {}; struct mole_tag : public ordinal<14> {}; struct candela_tag : public ordinal<15> {}; struct radian_tag : public ordinal<16> {}; struct degree_tag : public ordinal<17> {}; struct gradian_tag : public ordinal<18> {}; struct steradian_tag : public ordinal<19> {}; // specializations of base_unit_converter and // unit_info namespace SI { typedef make_system< mpl::map< mpl::pair<length_tag, meter_tag>, mpl::pair<mass_tag, scaled_system<gram_tag, 1000> >, mpl::pair<time_tag, second_tag>, mpl::pair<current_tag, ampere_tag>, mpl::pair<temperature_tag, kelvin_tag>, mpl::pair<amount_tag, mole_tag>, mpl::pair<intensity_tag, candela_tag>, mpl::pair<angle_tag, radian_tag>, >
::type system_tag; }
Everything else in si/* remains the same make_system and scaled_system each take about 50 lines of code to implement. In Christ, Steven Watanabe