how-to bublesort in OO perl

#source:http://blob.perl.org/tpc/1998/Perl_Language_and_Modules/Efficient%20Perl/handout.html

sub bubblesort {

    my $self = shift ; 

    my ( $array ) = @_;

    use integer;        # More speed.

    print "\@_ is @_ \n" ; 

    print "\$array is $array \n" ; 

    print "\$#$array is $#$array \n" ; 

    my $lastj   = $#$array or return $array ; # 0 or 1 element array is sorted already just returned

    my $firstj  = 1;

    my ( $i, $j, $keepj, $big );

    # return $array  if $firstj > $lastj;     # 0 or 1 element array is sorted.

    while ( $firstj ) {

        # Run from

        # ( $firstj - 1, $firstj ) .. ( $lastj - 1 , $lastj ),

        # swapping when out of order.

        for ( $j = $firstj, $i = $j - 1,

              $keepj = $lastj, $firstj = 0;

          $j <= $keepj;

          $i = $j++ ) {

        next unless $array->[ $i ] gt $array->[ $j ];

        # Remember where we started if this is the first swap

        # (but do not try to compare with the predecessor of 0)

        $firstj = $firstj || $i || $j;

        # Something to swap, try for a run of swaps.

        # Remove the element that must swap up.

        $big = splice @$array, $i, 1;

        # Use $j < $keepj instead of $j <= $keepj

        # because the array is one shorter right now.

        # We already tested the $j entry that has been

        # shifted to $j-1.

        ++$j while $j < $keepj && $array->[ $j ] lt $big;

        # Put back the removed element in its new place.

        splice @$array, $j, 0, $big;

        # fix $j for the splice, and revalidate $i.

        $i = $j++;

        $lastj = $i;

        }

    }

    return $array ; 

} #eof sub