I want to allow users of my Float12x module the choice of faster or more precise trig (at the moment, 103bits over 0..2pi is ~30% faster than 106bits; the more precise version also handles larger arguments). The choice needs to be made before the using statement, as it governs the inclusion of either one of two small source files.
This is a binary choice; I'd like to know how to do this for a multi-ary choice, too.
