Kryzarel

private float CalculateFinalValue()
{
    float finalValue = BaseValue;
    float sumPercentAdd = 0; // This will hold the sum of our "PercentAdd" modifiers

    for (int i = 0; i < statModifiers.Count; i++)
    {
        StatModifier mod = statModifiers[i];

        if (mod.Type == StatModType.Flat)

Kryzarel

public readonly float Value;
public readonly StatModType Type;
public readonly int Order;
public readonly object Source; // Added this variable

// "Main" constructor. Requires all variables.
public StatModifier(float value, StatModType type, int order, object source) // Added "source" input parameter
{
    Value = value;
    Type = type;

Kryzarel

// Hypothetical item class
public class Item
{
    public void Equip(Character c)
    {
        // We need to store our modifiers in variables before adding them to the stat.
        mod1 = new StatModifier(10, StatModType.Flat);
        mod2 = new StatModifier(0.1, StatModType.Percent);
        c.Strength.AddModifier(mod1);
        c.Strength.AddModifier(mod2);

Kryzarel

public bool RemoveAllModifiersFromSource(object source)
{
    bool didRemove = false;

    for (int i = statModifiers.Count - 1; i >= 0; i--)
    {
        if (statModifiers[i].Source == source)
        {
            isDirty = true;
            didRemove = true;

Kryzarel

public class Item
{
    public void Equip(Character c)
    {
        // Create the modifiers and set the Source to "this"
        // Note that we don't need to store the modifiers in variables anymore
        c.Strength.AddModifier(new StatModifier(10, StatModType.Flat, this));
        c.Strength.AddModifier(new StatModifier(0.1, StatModType.Percent, this));
    }

Kryzarel

public bool RemoveModifier(StatModifier mod)
{
    if (statModifiers.Remove(mod))
    {
        isDirty = true;
        return true;
    }
    return false;
}

Kryzarel

public readonly ReadOnlyCollection<StatModifier> StatModifiers; // Add this variable

public CharacterStat(float baseValue)
{
    BaseValue = baseValue;
    statModifiers = new List<StatModifier>();
    StatModifiers = statModifiers.AsReadOnly(); // Add this line to the constructor
}

Kryzarel

// Add this variable
private float lastBaseValue = float.MinValue;

// Change Value
public float Value {
    get {
        if(isDirty || lastBaseValue != BaseValue) {
            lastBaseValue = BaseValue;
            _value = CalculateFinalValue();
            isDirty = false;

Kryzarel

public enum StatModType
{
    Flat = 100,
    PercentAdd = 200,
    PercentMult = 300,
}

Kryzarel

protected bool isDirty = true;
protected float lastBaseValue;
protected float _value;
public virtual float Value {}

protected readonly List<StatModifier> statModifiers;

public virtual void AddModifier(StatModifier mod);
public virtual bool RemoveModifier(StatModifier mod);
public virtual bool RemoveAllModifiersFromSource(object source);