On Wednesday, January 05, 2011 15:40:37 BCS wrote: > Andrei Alexandrescu <seewebsiteforem...@erdani.org> wrote: > > (c) Numeric issues as I described (and no amount of rhetoric will set > > that straight; FWIW given the obvious question of scaling you need to > > prove it works, not me to prove it doesn't) > > (d) Unrealized potential (if we approve this, backward compatibility > > will prevent more comprehensive libraries having the same aim but a > > different design). This argument is to be taken with a grain of salt as > > in general it can be easily abused. What I'm saying is that once this > > library is in we may as well forget about scaled units a la boost units > > (which are the kind I'd want to use). > > We have both said our piece on these, what do others think? I'd be > particularly interested in what Don has to say on the numeric issues. Does > an extra layer or two of FP rounding really mater.
Personally, I tend to cringe when I see much in the way of floating points in anything that needs precision, but it's not like you can avoid it in this case. Regardless, I agree with pretty much everything that Andrei has said. I particularly don't like that the values are all in meters internal - _especially_ when dealing with floating point values. I'd be very worried about precision issues. The Boost solution seems like a solid one me. However, I'm not likely the sort of person who's going to be using a unit library very often. I just don't deal with code that cares about that sort of thing very often. - Jonathan M Davis