USignals

This package provides a simple and easy to use signal system for Unity.

Installation

To install this package, you can copy this url to the package manager:

https://github.com/Yuuko-Games/USignals.git

Usage

To use this package, you need to know the two types of signals that are available:

• Signal<T>(value): A signal that holds a value of type T.
• Signal<T>(func, signals): A signal that holds a value of type T that is calculated by a function that depends on other signals.

Basic example code

var signalA = new Signal<int>(5);
var signalB = new Signal<int>(10);

Debug.Log($"Initial signalA value: {signalA.Value}");
Debug.Log($"Initial signalB value: {signalB.Value}");

var signalC = new Signal<int>(() => signalA.Value + signalB.Value, signalA, signalB);
var signalD = new Signal<int>(() => signalC.Value * 2, signalC);

Debug.Log($"Initial signalC value: {signalB.Value}"); // 15
Debug.Log($"Initial signalD value: {signalD.Value}"); // 30

signalA.Value = 15; // signalA, signalC and signalD will be updated

Debug.Log($"Current signalA value: {signalA.Value}"); // 15
Debug.Log($"Current signalB value: {signalB.Value}"); // 10 -- didn't change
Debug.Log($"Current signalC value: {signalC.Value}"); // 25
Debug.Log($"Current signalD value: {signalD.Value}"); // 50

Displaying the signals values in the console

var signal = new Signal<int>(5);

Debug.Log($"Displays the signal's value (int -> string): {signal.Value}");
Debug.Log($"Displays the signal's value (string): {signal}");

Working with MonoBehaviour scripts

private void Awake()
{
    // Use to initialize the signals
}

private void Start()
{
    // Use it to subscribe to the OnChanged event, to ensure that the signals are ready
}

Example

This is an example of how to use the signals in a MonoBehaviour script:

Suppose you have a PlayerHealth script that holds the player's health and if it's dead or not.

using UnityEngine;
using USignals;

public class PlayerHealth : MonoBehaviour
{
    // Initialize the value signal in the declaration
    public readonly Signal<int> health = new(5);

    // Initialize the function signal in the Awake method
    public Signal<bool> isDead;

    private void Awake()
    {
        // Use to initialize the signals
        isDead = new Signal<bool>(() => health.Value <= 0, health);
    }

    // Imagine this is a damage event
    private void Update()
    {
        if (Input.GetKeyDown(KeyCode.Space) && !isDead.Value)
        {
            health.Value--;
        }
    }
}

In the HealthDisplay script, you can display the player's health and if the player is dead.

using TMPro;
using UnityEngine;

public class HealthDisplay : MonoBehaviour
{
    [SerializeField] private PlayerHealth playerHealth;
    [SerializeField] private TMP_Text healthText;
    [SerializeField] private TMP_Text deadText;

    private void Start()
    {
        playerHealth.health.OnChanged += () => healthText.text = $"{playerHealth.health}";
        playerHealth.isDead.OnChanged += () => deadText.text = playerHealth.isDead.Value ? "Dead" : "Alive";
    }
}

Best practices

Basically, you should never do this:

• DON'T reassign the signals to a new Signal value after the initialization.

Warning

To avoid circular dependencies, it is REALLY RECOMMENDED to build readonly variables for the signals when working on MonoBehaviour scripts, and only update its values from the given API.

You should do this:

• DO initialize the signals with a value or a function that depends on other signals.
• DO update the signals values from the given API like:

signal.Value = newValue;

• You can check when a value changes by using the OnChanged event with:

signal.OnChanged += () => {
    Debug.Log($"Signal value changed to: {signal.Value}");
};

• On MonoBehaviour scripts
  • DO use the signals as readonly variables when working on MonoBehaviour scripts.
  • DO initizalize the signals in the Awake method.
  • DO subscribe to the OnChanged event in the Start method.

License

This package is licensed under the MIT License.