use strict;
 
my @lines = <DATA>;
my $maxsize = 0;
map {chomp; $maxsize = ($maxsize>length)?($maxsize):(length)} @lines;
print "max size: $maxsize\n";
 
my $bar = '*' x ($maxsize +4) . "\n";
my $format = '%' . $maxsize . '.' . $maxsize . 's';
foreach (@lines)
{
  print($bar);
  printf("* $format *\n", $_);
  print($bar);
}
 
 
__DATA__
some lines
that are of different sizes
Some small
really small.
----------------some large---------------------
--------------------------------------------------some huge--------------------------------------------------
...