On Wednesday, 3 April 2013 at 03:26:54 UTC, Andrei Alexandrescu
wrote:
On 4/2/13 11:10 PM, Steven Schveighoffer wrote:
On Tue, 02 Apr 2013 16:32:21 -0400, Walter Bright
<newshou...@digitalmars.com> wrote:
On 4/2/2013 12:47 PM, Andrei Alexandrescu wrote:
I used to lean a lot more toward this opinion until I got to
work on
a C++
codebase using signed integers as array sizes and indices.
It's an
pain all over
the code - two tests instead of one or casts all over, more
cases to
worry
about... changing the code to use unsigned throughout ended
up being an
improvement.
For example, with a signed array index, a bounds check is two
comparisons rather than one.
Why?
struct myArr
{
int length;
int opIndex(int idx) { if(cast(uint)idx >= cast(uint)length)
throw new
RangeError(); ...}
}
-Steve
As I said - either two tests or casts all over.
Andrei
Yeah, but I think that what this is, is demonstrating what a
useful concept a positive integer type is. There's huge value in
statically knowing that the sign bit is never negative.
Unfortunately, using uint for this purpose gives the wrong
semantics, and introduces these signed/unsigned issues, which are
basically silly.
Personally I suspect there aren't many uses for unsigned types of
sizes other than the full machine word. In all the other sizes, a
positive integer would be more useful.
