CODE EXAMPLE FOR CSHARP

unity custom update

using UnityEngine;
 using System.Collections;

 public class DamageSource : MonoBehaviour {
     protected float damageAmount = 10f;

     //not 100% necessary, but handy for an example of how to 
     //handle damage based on the attacker (which is 
     //relevant for info sent in the OnTakeDamage() method
     protected ElementType elementType = ElementType.Normal;

     //we use a function for getting the damage this 
     //DamageSource can do because it lets us overwrite it.
     //Eg, if the enemy is weakened, you can factor that 
     //in and return a lesser amount of damage.
     public float GetDamageAmount() {
         return damageAmount;
     }

     public ElementType GetElementType() {
         return elementType;
     }
 }

 //kinds of elements available for damage / resistance calculations
 public enum ElementType {
     Normal,
     Fire,
     Ice,
     Lightning
 }