var other : Transform;
if (other) {
var dist = Vector3.Distance(other.position, transform.position);
print ("Distance to other: " + dist);
}

using UnityEngine;
using System.Collections;

public class example : MonoBehaviour {
public Transform other;
void Awake() {
if (other) {
float dist = Vector3.Distance(other.position, transform.position);
print("Distance to other: " + dist);
}
}
}

import UnityEngine
import System.Collections

class example(MonoBehaviour):

public other as Transform

def Awake():
if other:
dist as single = Vector3.Distance(other.position, transform.position)
print(('Distance to other: ' + dist))