Trigger event on variable change

Questions & Answers
1

Hi there,
how to make a custom event that triggers when a variables value is changed.

thanks!

2

Using simple variables, the best you can do is constantly check in update whether or not is has changed:

private int m_MyVar = 0;
public int myVar = 0;

public delegate void OnVariableChangeDelegate(int newVal);
public event OnVariableChangeDelegate OnVariableChange;

private void Update()
{
    if (myVar != m_MyVar && OnVariableChange != null)
    {
        m_MyVar = myVar;
        OnVariableChange(myVar);
     }
}

However, if you can use properties this is a little cleaner because you know when a variable is set:

private int m_MyVar = 0;
public int MyVar
{
    get {return m_MyVar;}
    set {
        if (m_MyVar == value) return;
        m_MyVar = value;
        if (OnVariableChange != null)
            OnVariableChange(m_MyVar);
    }
}
public delegate void OnVariableChangeDelegate(int newVal);
public event OnVariableChangeDelegate OnVariableChange;

To subscribe and listen to either of these events:

private void Start()
{
    componentWithEvent.OnVariableChange += VariableChangeHandler;
}

private void VariableChangeHandler(int newVal)
{
    //do whatever
}
3

@Zwusel In the Inspector, there is “on value changed” for sliders on the UI
just have it call a function to tell all classes the user has changed the slider.