making a boomerang effect in a 2D enviorment

Questions & Answers
1

I am trying to make the main character throw a projectile and it comes right back the way it came but i really dont know how to accomplish this, I thought maybe I can say if it reaches a distance from point 0,0 it can come back but that didnt work. i just want it to go in straight line forward and a straight line back.
Im doing it in C# but any help will do.

2

Yes, the distance idea is right. You can do something like :

public float speed = 1f; // default speed 1 unit / second
public float distance = 5f; // default distance 5 units
public Transform boomerang; // the object you want to throw (assign from the scene)
private float _distance; // the distance it moves
private bool _back; // is it coming back

public void Shoot ()
{
    _distance = 0; // resetting the distance
    back = false; // resetting direction
    enabled = true; // enabling the component, so turning the Update call on
}

private void Update ()
{
    float travel = Time.deltaTime * speed;
    if (!back)
    {
        boomerang.Translate(Vector3.forward * travel); // moves object
        _distance += travel; // update distance
        back = _distance >= distance; // goes back if distance reached
    }
    else
    {
        boomerang.Translate(Vector3.forward * -travel); // moves object
        _distance -= travel; // update distance;
        enabled = _distance > 0; // turning off when done
    }
}

private void OnEnable ()
{
    boomerang.gameObject.SetActive (true); // activating the object
}
private void OnDisable ()
{
    boomerang.gameObject.SetActive (false);
}