Type-safe implementation of Unity's SendMessage

BumperZapper.cs

using UnityEngine;

public class BumperZapper : MonoBehaviour
{
    Rigidbody2D _rb;

    void Awake()
    {
        _rb = GetComponent<Rigidbody2D>();
    }

    void FixedUpdate()
    {
        if (Input.GetKey(KeyCode. LeftArrow)) _rb.AddForce(-Vector2.right);
        if (Input.GetKey(KeyCode.RightArrow)) _rb.AddForce( Vector2.right);
        if (Input.GetKey(KeyCode.   UpArrow)) _rb.AddForce( Vector2.up);
        if (Input.GetKey(KeyCode. DownArrow)) _rb.AddForce(-Vector2.up);

        // Send the GetZapped messages to objects under the mouse.
        var zapee = gameObjectUnderMouse();
        if (zapee != null) {
            // Message arguments are defined by populating the message type's fields.
            zapee.SendTypedMessage(new Messages.GetZapped {
                intensity = Random.value
            });
        }
    }

    void OnCollisionEnter2D(Collision2D col)
    {
        // Message types with no fields can be invoked with a type argument, like this:
        col.gameObject.SendTypedMessage<Messages.GetBumped>();
    }
    
    static GameObject gameObjectUnderMouse()
    {
        var hit = Physics2D.Raycast(Camera.main.ScreenToWorldPoint(Input.mousePosition), Vector2.zero);
        return hit.collider != null ? hit.collider.gameObject : null;
    }
}

Messages.cs

static public class Messages
{
    // Messages are defined as types.  They may be structs or classes, and they
    // do not require any member variables.

    public struct GetBumped { }

    public struct GetZapped {
        public float intensity;
    }
}

Receiver.cs

using UnityEngine;

// Scripts define which messages they respond to by implementing the Message<T> interface.
public class Receiver : MonoBehaviour
  , Message<Messages.GetBumped>
  , Message<Messages.GetZapped>
{
    void Message<Messages.GetBumped>.Receive(Messages.GetBumped _)
    {
        transform.localScale = (Random.value + 0.5f) * Vector3.one;
    }

    void Message<Messages.GetZapped>.Receive(Messages.GetZapped messageData)
    {
        transform.position += (Random.value - 0.5f) * Vector3.one * messageData.intensity;
    }
}

SendTypedMessage.cs

using UnityEngine;

public interface Message <T>
{
    void Receive(T param);
}

static public class GameObject_SendTypedMessage
{
    static public void SendTypedMessage <T> (this GameObject target, T param = default(T))
    {
        var targs = target.GetComponents(typeof(Message<T>));
        foreach (var targ in targs) {
            (targ as Message<T>).Receive(param);
        }
    }
}