Re: More effective way to increase two elements of a list in parallel?

[wade]

I see a few things, here.

First, you should always use:

use strict;
use warnings;
use diagnostics; # not everyone puts this in but I think it's helpful

But that's just general stuff. The big question I have is why use a while (especially with the -- eesh -- next statement) when an if is really what you want? Rewriting this using your (excellent) suggestion of the reformulated for:

foreach my $pdu_num (3 .. 8) 
{
        $pdu_num = 11 - $pdu_num unless defined $order;
        if (my $node = shift @nodes)
        {
                $map{$node} = $pdu . '['.$pdu_num.']';
        }
}

gives, I think, a much clearer chunk of code

[FunkyMonk]

Note that

if (my $node = shift @nodes)
{
    $map{$node} = $pdu . '['.$pdu_num.']';
}

is not the same as the OP's code. Your code won't process the if if the first element of @nodes is false. Better to use

if (@nodes) {
    my $node = shift @nodes;
    $map{$node} = $pdu . '['.$pdu_num.']';
}