Re: [boost] Interest in dimension/unit-checking library?

Matt Calabrese wrote: (discussion about implicit versus explicit conversion of units omitted) It could be just me, but I'd like to be at least warned if I manage to write code that contained quantity_in_inches + quantity_in_meters or even quantity_in_millimeters - quantity_in_kilometers Both to me are signs that something went wrong. And if I recall correctly that was the problem with some space mission that went wrong. I just don't think implicit conversion of units would have been the right fix for that problem. Is it really sometimes necessary or desirable to write computation code that mixes different units for the same dimension? Is anyone patient and indulgent enough to explain to this naive mathematician why?