> For the complete documentation index, see [llms.txt](https://blackboard.crashkonijn.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://blackboard.crashkonijn.com/examples/05_lists.md).

# 05 Lists

This example shows you how to use lists in a blackboard.

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

![Example 05 Lists editor](/files/lYK6wyBGvpph9E1BC1dF)

## ListBlackboard.cs

```csharp
using System.Collections.Generic;
using System.Linq;
using CrashKonijn.RabbitBlackboard.Contracts;

namespace CrashKonijn.BlackboardPro.Blackboards.Examples
{
    public partial class ListBlackboard : BlackboardBehaviour
    {
        private int startHealth = 100;

        // Lists can be of any type
        private List<int> changes;

        // This is a computed property, showing health being equal to startHealth plus the sum of all changes.
        private static int health(Signals.StartHealth startHealth, Signals.Changes changes) => startHealth.Value + changes.Value.Sum(x => x);
    }
}

```

## ListsHealthBehaviour.cs

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

namespace CrashKonijn.BlackboardPro.Examples._05_lists
{
    [RequireComponent(typeof(ListBlackboard))]
    public class ListsHealthBehaviour : MonoBehaviour
    {
        /* 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;

        /* Simple hack to show a button in the editor */
        [Header("Clears the changes list")]
        [Button(nameof(Clear))]
        public string clearButton;

        private ListBlackboard blackboard;

        public ListBlackboard Blackboard
        {
            get
            {
                if (this.blackboard == null)
                {
                    this.blackboard = this.GetComponent<ListBlackboard>();
                }

                return this.blackboard;
            }
        }

        public void DoDamage()
        {
            this.Blackboard.Changes.Add(-10);
        }

        public void Heal()
        {
            this.Blackboard.Changes.Add(10);
        }

        public void Clear()
        {
            this.Blackboard.Changes.Clear();
        }
    }
}

```


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