sub sub1 {
   my %args = ( arg1 => 'default',
                arg2 => 0,
                arg3 => undef,
                @_
               );
}
[download]

I personally prefer this approach because it 1) tells me what parameters I am expecting and 2) it allows me to set defaults. Yes, it takes up a lot of space visually, but who the heck cares since it makes the code that much more readable. :-)