Using <=> is clever, I think. And by that I mean that it invokes a less common set of symbols to come to a result in a surprising and elegant way.

I'm not sure that is good, though. Assuming that if either variable is zero you should return 0, my first thought was

if ($left > 0) {
  if ($right > 0) { # both pos
    return 1
  }
} elsif ($left < 0) {
  if ($right < 0) { # both neg
    return 1
  }
}
return 0;
[download]

I think this is bad because its a whole bunch of lines. On the other hand, I think its good because its dead obvious, and probably pretty fast (fewer compares and jumps than even the double '<=>' version).

ymmv. "What is good?", asked jesting Pilate, not waiting for an answer.

--woody

Using the shuttles I'm basiclaly asking "Do these 2 numbers compare to zero the same way"

Personally i'm a fan of the $left * $right > 0 solution, it has a nice mathy feel. although may have issues for massive numbers etc (Corion++ on that count)

@_=qw; ask f00li5h to appear and remain for a moment of pretend better than a lifetime;;s;;@_[map hex,split'',B204316D8C2A4516DE];;y/05/os/&print;

sub same_sign {
  (0 <=> $_[0]) == (0 <=> $_[1])
                ||
       (! $_[0] || ! $_[1]);
}
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to check for either operand being somewhat false ;-)

_($_=" "x(1<<5)."?\n".q·/)Oo.  G°\        /
                              /\_¯/(q    /
----------------------------  \__(m.====·.(_("always off the crowd"))."·
");sub _{s./.($e="'Itrs `mnsgdq Gdbj O`qkdq")=~y/"-y/#-z/;$e.e && print}