Interesting... are whirleygigs and spinners also one of the rites of passage as one becomes more adept at perl? (Just curious...)

As to the code, I don't think I've seen one that waited for the timer-tick like that. Would the use of "\r" be an issue? (I would have suspected the use of the backspace character "\b" instead, but I haven't tried it myself yet... might also depend on the terminal, though.)

Personally, I tend to do something like the following (adapted here from a previous posting), but that's just me:

#!/usr/bin/perl -w

use strict;

$| = 1;
my @spinner = ('|', '/', '-', '\\');
my $bigscale = 100_000;
my $scale = 100;
my $index = 0;

  # replace the following two lines 
  # with a loop appropriate to the project
  my $in_loop = 1;
  while ($in_loop) {

    # Do work.
    print $spinner[($index++ / $scale) % 4], "\b";
    print '.' unless ($index % $bigscale);

    # And for completeness, for demonstration purposes...
    $in_loop = 0 if ($index > (($scale / 2) * $bigscale));
  }
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Updated: (08 Dec 2003) Corrected use of "rites" instead of "rights." (Thank you, liz, for the correction.)

One thing you have to keep in mind, though, is that shift and push are expensive. It's a lot cheaper to index++ % @spin.

It doesn't matter for this code, since you're only going to shift/push once per second, but you might want to keep it in mind if you ever need to do this kind of array looping in a tighter loop.

ObBenchmark:

On a perl 5.8 Linux system, using an index clocks in 133% faster than using shift/push.

For longer running code in a tight loop, you also need to be aware that at some point $ndx++ stops working. For instance, with normal IEEE doubles:

$ perl -we'$x = $y = 2**53-1; ++$x; print $x-$y'
1
$ perl -we'$x = $y = 2**53; ++$x; print $x-$y'
0
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On my computer, in a tight loop, you could reach this point in just 30 years :)

Oh well, if your loop is a bit looser, Y2038 could get you before 2^53 could. :)

Mike

You have a point, but.. Running your benchmark on my machine gives me a rate of over 900,000 shift spins per sec. That is about 45,000 times faster than I need it.

Makeshifts last the longest.