"Unsigned-related bugs never occur in real code."

[Andrei Alexandrescu]

Rainer Deyke wrote:
> Andrei Alexandrescu wrote:
>> std.traits has a Unsigned template. I plan to add two functions:
>> signed(x) and unsigned(x), which transform the integral x into the
>> signed/unsigned integral of the same size. Generic code could then call
>> signed or unsigned wherever necessary. For abs, they'd have to call
>> abs(signed(expr)) which I believe clarifies intent and averts bugs like
>> mine.
> 
> It would also be completely and utterly wrong.  The correct replacement
> is this:
> 
> T result;
> if (isSigned!T) {
>   result = abs(v);
> } else {
>   result = v;
> }
> 
> ....which works, but is a lot less concise than simply saying
> 'v = abs(v)'.  If I ever found myself writing the above in actual code,
> I'd be tempted to factor it out into its own function, call that
> function 'abs', and consistently use that function instead of the 'abs'
> in Phobos.

Depends! In my case, your fix is wrong.

Andrei