On Monday, 24 September 2012 at 17:47:33 UTC, David Piepgrass
wrote:
However, unit checking cannot be done satisfactorially in a
library; it has two main problems when provided that way:
1. It's too bulky (too much syntax required, as units have to
be spelled out constantly)
2. Values with traditionally-typed units don't interoperate
with existing libraries, including very simple functions such as
int abs(int x) { return x > 0 ? x : -x; }
int square(int x) { return x*x; }
You can define an inplicit conversion from e.g. 'Unit!"pixels"'
to 'int' but then you'll need to manually cast it back, and the
compiler can't check your cast to make sure it's correct.
IMO, solving these two problems requires a parallel type system
to infer unit relationships automatically, either with direct
language support, or a separate analysis tool that uses the
compiler as a service (currently not possible with D).
+1
You can partially solve the function arg/return value problem by
making those functions templates but:
(a) This doesn't help you with existing functions (e.g. trig
function in std.math)
(b) It stops those functions from being virtual.
(c) Generally makes the functions more difficult to work with (no
common type, horrible compilation errors)
