[phobos] [Fwd: "Unsigned-related bugs never occur in real code."]

[Sean Kelly]

My first inclination would be for abs to only accept signed values.  Unsigned values don't really seem appropriate for unchecked math operations.

On Jan 20, 2010, at 8:50 PM, Andrei Alexandrescu wrote:

> Is there anything we can do about this?
> 
> Andrei
> 
> -------- Original Message --------
> Subject: "Unsigned-related bugs never occur in real code."
> Date: Wed, 20 Jan 2010 20:42:50 -0800
> From: Andrei Alexandrescu <SeeWebsiteForEmail at erdani.org>
> Organization: Digital Mars
> Newsgroups: digitalmars.D
> 
> "It's an academic problem. Don't worry about it and move on."
> 
> That's what Walter kept on telling me. Yet I've spent the better part of
> an hour reducing a bug down to the following:
> 
> import std.math, std.stdio;
> 
> void main() {
>    auto a = [ 4, 4, 2, 3, 2 ];
>    float avgdist = 0;
>    uint count;
> 
>    foreach (i, e1; a) {
>        foreach (j, e2; a) {
>            if (i == j) continue;
>            if (e1 != e2) continue;
>            ++count;
>            avgdist += abs(i - j);
>        }
>    }
> 
>    writeln(count, " ", avgdist / count);
> }
> 
> May this post be an innocent victim of the war against unsigned-related
> bugs.
> 
> 
> Andrei
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