07/06 디자인 패턴 기초 - Observer 패턴, Event 기반 설계

public class PlayerHealth  
{  
    public event Action<int, int>? OnHealthChanged;

    public int Current { get; private set; }  
    public int Max { get; }

    public PlayerHealth(int max)  
    {  
        Max = max;  
        Current = max;  
    }

    public void TakeDamage(int damage)  
    {  
        if (damage <= 0) return;  
        Current = Math.Max(0, Current - damage);  
        OnHealthChanged?.Invoke(Current, Max);  
    }  
}

public class HealthView  
{  
    public void Bind(PlayerHealth health)  
    {  
        health.OnHealthChanged += Render;  
        Render(health.Current, health.Max);  
    }

    private void Render(int current, int max)  
    {  
        Console.WriteLine($"HP: {current}/{max}");  
    }  
}