if ($] > 5.010) { use Super::Cool::Module; $supercool = 2; } elsif (($] <= 5.010) && ($] > 5.008)) { use Almost::Cool::Module; $supercool = 1; } elsif ($] <= 5.008) { print "No module available for this ancient perl\n"; $supercool = 0; ## insert code here to duplicate the functionality of the newer modules. } ### then later in the code if ($supercool == 2) { # do stuff with the super cool functions } elsif ($supercool == 1) # do stuff with the less cool functions } else { # 10000 lines of code to implement the super cool functions in ancient perl. }