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

methodName Name of the method to call.
value Optional parameter for the method.
options Should an error be raised if the target object doesn't implement the method for the message?
Description

Calls the method named methodName on every MonoBehaviour in this game object.

The receiving method can choose to ignore the argument 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.

Note that messages will not be sent to inactive objects (ie, those that have been deactivated in the editor or with the GameObject.SetActive function).
	// Calls the function ApplyDamage with a value of 5
	SendMessage ("ApplyDamage", 5.0);
	
	// Every script attached to the game object 
	// 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() {
        SendMessage("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:
		SendMessage('ApplyDamage', 5.0F)