$a = 3; $b = 4; $op = 'le';

##</code><code>##

if ($op eq 'le') {
  if ($a <= $b) {
    do something
  } else {
    do something else
  }
} elsif ($op eq 'ge')
  if ($a >= $b) {
    do something
  } else {
    do something else
  }
} elsif ....