RE (tilly) 1 (possibilities): interchanging variables the tough way

With a sub you can actually stop having to retype the list two times. Which is a nice feature:

$a=1,$b=2,$c=3,$d=4,$e=5;
&rotate($a, $b, $c, $d, $e);
print "\$a=$a,\$b=$b,\$c=$c,\$d=$d,\$e=$e\n";

sub rotate {
    my $temp = $_[0];
    foreach (0..($#_ - 1)) {
        $_[$_] = $_[$_+1];
    }
    $_[-1] = $temp;
}
[download]

OK, this is definitely slower, but you see the point.

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RE: (tilly) 2 (possibilities): interchanging variables the tough way by tilly (Archbishop) on Aug 31, 2000 at 16:08 UTC
Looking at this bugs me. Manipulating your input arguments this way works, but the side-effects can surprise and amaze. I would not do this lightly. My overall feeling is that if you feel the need to rotate your data, you should have an array rather than a list of variables. Then you could `push @array, shift @array;` [download] much faster, without resorting to nasty side-effects. Generally when I see myself wanting to resort to "bad" techniques like side-effects, I take that as a danger sign and go looking for a more fundamental mistake in my code...	[reply] [d/l]

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RE: (tilly) 2 (possibilities): interchanging variables the tough way
by tilly (Archbishop) on Aug 31, 2000 at 16:08 UTC

Manipulating your input arguments this way works, but the side-effects can surprise and amaze. I would not do this lightly.

My overall feeling is that if you feel the need to rotate your data, you should have an array rather than a list of variables. Then you could

push @array, shift @array;
[download]

Generally when I see myself wanting to resort to "bad" techniques like side-effects, I take that as a danger sign and go looking for a more fundamental mistake in my code...

[reply]
[d/l]