Event Management - trying to figure out the basics

Scripting C# & .NET
1

Hi guys, I’m reading a Unity C# textbook and I’m trying to figure out the Event Management example there. I think however I’m missing some sort of crucial component. I have this script attached to a game object, but when “health” or “ammo” get too low (I use the mouse keys to reduce their values), nothing is printed in the console (I put Debug.Log there, and in Debug Mode I see that health and ammo do indeed decrease)… how come the console doesn’t print anything?

using UnityEngine;
using System.Collections;
public class EnemyObject : MonoBehaviour
{
    //-------------------------------------------------------
    //C# accessors for private variables
    public int Health
    {
        get{return _health;}
        set
        {
            //Clamp health between 0-100
            _health = Mathf.Clamp(value, 0, 100);
            //Check if dead
            if(_health <= 0)
            {
                OnDead();
                return;
            }
            //Check health and raise event if required
            if(_health <= 20)
            {
                OnHealthLow();
                return;
            }
        }
    }
    //-------------------------------------------------------
    public int Ammo
    {
        get{return _ammo;}
        set
        {
            //Clamp ammo between 0-50
            _ammo = Mathf.Clamp(value,0,50);
            //Check if ammo empty
            if(_ammo <= 0)
            {
                //Call expired event
                OnAmmoExpired();
                return;
            }
        }
    }
    //-------------------------------------------------------
    //Internal variables for health and ammo
    private int _health = 100;
    private int _ammo = 50;
    //-------------------------------------------------------
    // Update is called once per frame
    void Update ()
    {
        if (Input.GetMouseButtonDown (0)) {
            _ammo -= 10;
        }
        if (Input.GetMouseButtonDown (1)) {
            _health -= 20;
        }
    }
    //-------------------------------------------------------
    //This event is called when health is low
    void OnHealthLow()
    {
        //Handle event response here
        Debug.Log ("OnHealthLow");

    }
    //-------------------------------------------------------
    //This event is called when enemy is dead
    void OnDead()
    {
        //Handle event response here
        Debug.Log ("OnDead");
    }
    //-------------------------------------------------------
    //Ammo run out event
    void OnAmmoExpired()
    {
        //Handle event response here
        Debug.Log ("OnAmmoExpired");

    }
    //-------------------------------------------------------
}
2

You’re making the common mistake of using the backing fields directly, rather than the properties you’ve set up to manage them. In other words, don’t use the ones that start with “" anywhere except in the “getter” and “setter” of the property that’s managing it. That’s why we start them with "”, so we know that they’re backing fields and not to use them.

void Update ()
{
    if (Input.GetMouseButtonDown (0)) {
        Ammo -= 10;
    }
    if (Input.GetMouseButtonDown (1)) {
        Health -= 20;
    }
}
1 Like
3

Many thanks Lysander!