// Create a ray from the transform position along the transform's z-axis

var ray = new Ray (transform.position, transform.forward);

using UnityEngine;
using System.Collections;

public class example : MonoBehaviour {
    public Ray ray = new Ray(transform.position, transform.forward);
}

import UnityEngine
import System.Collections

class example(MonoBehaviour):

    public ray as Ray = Ray(transform.position, transform.forward)