Re: [Boost-users] Boost.Units Example: Convert between nautical mile and imperial foot

AMDG On 09/26/2018 08:29 PM, Gavin Lambert via Boost-users wrote:

Oddly, given these:

BOOST_UNITS_DEFAULT_CONVERSION(imperial::length_base_unit, si::length); BOOST_UNITS_DEFAULT_CONVERSION(nautical::length_base_unit, si::length);

Only one of these two lines actually needs to be defined in order to make both direct conversions (ft -> nmi and nmi -> ft) compile.  Given that all three base units are independent, how does this work?

If you have only the first, then ft -> nmi is reduced to meters -> nmi which can be handled directly. The library doesn't care about the direction of the conversion. In Christ, Steven Watanabe