# 12 Class Blackboard

This example shows you how to use a class Blackboard.

These files can be found in the /Examples/\[example] and /Blackboards/Examples folders.

## ClassBlackboard.cs

```csharp
using System;
using CrashKonijn.RabbitBlackboard.Contracts;

namespace CrashKonijn.BlackboardPro.Blackboards.Examples
{
    // Make sure the class is serializable so it can show in the editor
    [Serializable]
    public partial class ClassBlackboard : IBlackboard
    {
        private int health = 50;
        private static bool isLowHealth(Signals.Health health) => health.Value < 50;
    }
}

```

## ClassBehaviour.cs

```csharp
using CrashKonijn.BlackboardPro.Blackboards.Examples;
using CrashKonijn.RabbitBlackboard.Contracts;
using UnityEngine;

namespace CrashKonijn.BlackboardPro.Examples._12_blackboard_class
{
    public class ClassBehaviour : MonoBehaviour
    {
        // You can manage your own instance of classes that implement IBlackboard.
        [SerializeField]
        private ClassBlackboard blackboard = new();

        /* Simple hack to show a button in the editor */
        [Header("Removes 10 health.")]
        [Button(nameof(DoDamage))]
        public string doDamageButton;

        /* Simple hack to show a button in the editor */
        [Header("Adds 10 health")]
        [Button(nameof(Heal))]
        public string healButton;

        private void OnEnable()
        {
            this.blackboard.IsLowHealthSignal.OnValueChanged.AddListener(this.OnLowHealthChanged);
            this.blackboard.HealthSignal.OnValueChanged.AddListener(this.OnStartPlayerHealthChanged);
        }

        private void OnDisable()
        {
            this.blackboard.IsLowHealthSignal.OnValueChanged.RemoveListener(this.OnLowHealthChanged);
            this.blackboard.HealthSignal.OnValueChanged.RemoveListener(this.OnStartPlayerHealthChanged);
        }

        private void OnLowHealthChanged(bool value)
        {
            Debug.Log($"Is low health changed to {value}");
        }

        private void OnStartPlayerHealthChanged(int value)
        {
            Debug.Log($"Start player health changed to {value}");
        }

        public void Heal()
        {
            this.blackboard.Health += 10;
        }

        public void DoDamage()
        {
            this.blackboard.Health -= 10;
        }
    }
}

```


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