# import a version of a module at compile time, die on failure
use Module 1.02; # dies unless Module is at least v1.02

# at runtime, find version and act on it.
eval {
   require Module; # if not installed, dies (go to end of eval)
   if ($Module::VERSION >= 1.02) {
      print "Module version is OK\n";
   }
   else {
      warn "Module is installed, but is too old";
      # maybe upgrade it here
   }
}
if ($@) { # run if 'require Module' fails
   warn "Module is not available";
   # maybe install it here
}