On 8/21/2016 2:47 AM, ag0aep6g wrote:
Upon use of the value, resolve which type to actually use for it. If the
use type requests a type between least and most, use that type for
evaluating the entire expression. If the use requests a type outside
that range, use the one closest (and, if the use is below the range,
complain about narrowing conversion).
So when only ubytes are involved, all calculations would be done on ubytes, no
promotions, right? There are cases where that would give different results than
doing promotions.
Consider `ubyte(255) * ubyte(2) / ubyte(2)`. If the operands are promoted to a
larger type, you get 255 as the result. If they are not, you have the equivalent
of `ubyte x = 255; x *= 2; x /= 2;` which gives you 127.
That's right.
The thing is, programmers are so used to C integral promotion rules they often
are completely unaware of them and how they work, despite relying on them. This
is what makes changing the rules so pernicious and dangerous.
I've had to explain the promotion rules to professionals with 10 years of
experience in C/C++, and finally stopped being surprised at that.
D does change the rules, but only in a way that adds compile time errors to
them. So no surprises.
(Nobody knows how function overloading works in C++ either, but that's
forgivable :-) )
