test for SendMessage target existance

Questions & Answers
1

Hi,

is there an easy way to test in code, whether a target game object received a message via SendMessage (implemented the message function)?

I want to write some kind of event system, where events are sent to child gameobject’s and the “bubble upwards” until they got delivered successfull.

As I see it, “SendMessageUpwards” will always deliver messages and does not stop sending the message if one game object received the message successfully.

I am more fluent in code. So an example:

public class Parent : MonoBehaviour
{
  void OnFoobar()
  {
    // not called, since Child does implement OnFoobar as well
  }
  void OnBarfoo()
  {
    // will be called, since Child does not implement OnBarfoo
  }
}

// not a child in terms of inheritance, but in terms of "transform.parent"
public class Child : MonoBehaviour
{
  void OnFoobar()
  {
  }
}

// meanwhile somewhere else..
var childObj = GameObject.Find("...");
childObj.MyUberSendMessageUpwards("OnFoobar") // will only call Child.OnFoobar
childObj.MyUberSendMessageUpwards("OnBarfoo") // will only call Parent.OnBarfoo

I could implement “MyUberSendMessageUpwards” by myself, if I had an easy way to test whether the target game object actually received the message.

2

SendMessage and similar functions don’t give us any useful clue about the receivers - they only print a message error, but don’t throw an exception (I tried the try-catch approach). Maybe some .NET feature could help you to write your own SendMessage, like InvokeMember (take a look at this article).

Another possibility - a lot less flexible, for sure - would be to use a static boolean flag and call SendMessage (with DontRequireReceiver option) for each parent. The function called via SendMessage should set this variable to true, signalling that a receiver was found and the loop could be ended - something like this:

// script SendMessageUp.js:

static var receiverFound: boolean;

function SendMsgUp(trf:Transform, func: String){
  receiverFound = false; // initialize flag
  while (!receiverFound && trf.parent){ // while flag==false and there's a parent...
    trf = trf.parent; // go one level above in the hierarchy
    // try to call the specified function
    trf.SendMessage(func, SendMessageOptions.DontRequireReceiver);
    // if receiver found, the function sets receiverFound to true
  }
}

// Example call:
  SendMsgUp(someObject.transform, "AnyFunction");

Remember that the function called must set receiverFound to true:

function AnyFunction(){
  SendMessageUp.receiverFound = true;
  // code of AnyFunction
}
3

just realized this question is from 2012…oh well…

Maybe youre over thinking? Im sorry if im misunderstanding the question. If a child receives a message and has the receiver, that is your way of knowing if the child received the message.

this is my setup, each object has the “BubbleUp” script attached
[118582-1.jpg*_|118582]
here is a script demonstrating how a message can be sent to a child object and have it “bubble up” to the parent. In the script the parent will send a message to the last child

using UnityEngine;

public class BubbleUp : MonoBehaviour {

    [HideInInspector]
    public int childIndex;
    BubbleUp[] children;
    bool isParent = false;
    private void Start()
    {
        if (transform.parent == null)
        {
            isParent = true;
            this.gameObject.name = "Parent";
            children = GetComponentsInChildren<BubbleUp>();
            for (int i = 0; i < children.Length; i++)
            {
                children*.childIndex = i + 1;*

children_.gameObject.name = “Child” + children*.childIndex.ToString();
}
children[children.Length - 1].SendMessage(“Receiver”, this.gameObject.name);
}
}*_

public void Receiver(string from)
{
if (!isParent)
{
Debug.Log(this.gameObject.name + " received message from " + from);
transform.parent.SendMessage(“Receiver”, from + " / " + this.gameObject.name);
}
else
{
Debug.Log(this.gameObject.name + " is the parent and received message from " + from);
}
}
}
and here is the result
[118583-2.jpg|118583]

_*