I have this implementation issue, which I'm having trouble applying good judgement, I'd like to survey opinions...
So, RGB colours depend on this 'normalised integer' concept, that is: unsigned: luminance = val / IntType.max signed: luminance = max(val / IntType.max, -1.0) So I introduce NormalizedInt(T), which does that. The question is, what should happen when someone does: NormalisedInt!ubyte nub; NormalizedInt!byte nb; auto r = nub + nb; What is typeof(r)? There are 3 options that stand out, and I have no idea which one is correct. 1. Compile error, mismatching NormalisedInt type arithmetic shouldn't work; require explicit user intervention. 2. 'Correct' result, ie, lossless; is(typeof(r) == NormalisedInt!short). Promote to type that doesn't lose precision, type conversion loses efficiency, but results always correct. 3. Do what normal int types do; is(typeof(r) == NormalisedInt!int) ie, apply the normal integer arithmetic type promotion rules. Classic pain-in-the-arse applies when implicitly promoted result is stored to a lower-precision value. Probably also slow (even slower) than option #2. Are there other options? I'm tempted by #1, but that will follow right through to the colour implementation, which will lead to colour type cast's all over the place.
