Component.BroadcastMessage
BroadcastMessage(methodName: string, parameter: object = null, options: SendMessageOptions = SendMessageOptions.RequireReceiver): void;
void BroadcastMessage(string methodName, object parameter = null, SendMessageOptions options = SendMessageOptions.RequireReceiver);
def BroadcastMessage(methodName as string, parameter as object = null, options as SendMessageOptions = SendMessageOptions.RequireReceiver) as void
BroadcastMessage(methodName: string, options: SendMessageOptions): void;
void BroadcastMessage(string methodName, SendMessageOptions options);
def BroadcastMessage(methodName as string, options as SendMessageOptions) as void
Parameters

methodName Name of the method to call.
parameter Optional parameter to pass to the method (can be any value).
options Should an error be raised if the method does not exist for a given target object?
Description

Calls the method named methodName on every MonoBehaviour in this game object or any of its children.

The receiving method can choose to ignore parameter by having zero arguments. if options is set to SendMessageOptions.RequireReceiver an error is printed when the message is not picked up by any component.
	/// Calls the function ApplyDamage with a value of 5
	BroadcastMessage ("ApplyDamage", 5.0);
	
	// Every script attached to the game object and all its children
	// that has a ApplyDamage function will be called.
	function ApplyDamage (damage : float) {
		print (damage);
	}
using UnityEngine;
using System.Collections;

public class Example : MonoBehaviour {
    void ApplyDamage(float damage) {
        print(damage);
    }
    void Example() {
        BroadcastMessage("ApplyDamage", 5.0F);
    }
}
import UnityEngine
import System.Collections

public class Example(MonoBehaviour):

	def ApplyDamage(damage as float) as void:
		print(damage)

	def Example() as void:
		BroadcastMessage('ApplyDamage', 5.0F)