get_option(‘home’)

Hello all,
I wanted to have 3 domains sending to the same wordpress, the only way I suceeded, and I dont like it, is this:

function get_option( $setting ) {
global $wpdb;
if (‘home’==$setting) { return ‘https://’.$_SERVER[‘HTTP_HOST’]; }

Is there a different possibility, without touching to the code ?

Thanks.