CODEWITHSUNDEEP
c#events
levelonehuman
levelonehuman

Reputation: 1505

Event Handling - sender as main class

Apologies if the title is misleading, but I'm not sure precisely what to call what I'm looking for here. I have the following "main" class:

public class Entity : INotifyPropertyChanged
{
    public string Name { get; set; }
    public EntityRole Role { get; set; }         
    public EntityStats Stats = new EntityStats();
    //Other stuff.... 
}

And a ... sub class? (proper name would be appreciated for this) ... called EntityStats:

public class EntityStats : INotifyPropertyChanged
{

    public int CurrentHealth 
    {
        get { return _currentHealth; }
        set
        {
            if (value != _currentHealth)
            {
                _currentHealth = value;
                OnPropertyChanged("CurrentHealth");
            }
        } 
    }

    //other properties...

    public event PropertyChangedEventHandler PropertyChanged;

    protected void OnPropertyChanged(PropertyChangedEventArgs e)
    {
        PropertyChangedEventHandler handler = PropertyChanged;
        if (handler != null)
            handler(this, e);
    }

    protected void OnPropertyChanged(string propertyName)
    {
        OnPropertyChanged(new PropertyChangedEventArgs(propertyName));
    }
}

Where an Entity object contains a property of type EntityStats.

On the other side of my code, I'm registering an Entity object to listen for PropertyChanged events:

public void RegisterEntity(Entity entity)
{            
    entity.Stats.PropertyChanged += entity_PropertyChanged;           
}

void entity_PropertyChanged(object sender, PropertyChangedEventArgs e)
{
    if (e.PropertyName == "CurrentHealth")
    {
        Message.Write("CurrentHealth property changed!");
        DeathCheck((Entity)sender);
    }
}

The issue I'm having is with DeathCheck((Entity)sender); -- Because the CurrentHealth OnPropertyChanged event is part of the EntityStats class, the object is of type EntityStats, which only contains part of the data I need.

How can I determine the Entity object that sender belongs to, or how can I refactor this code so that when a property inside EntityStats changes, an event is raised in the Entity class?

Upvotes: 1

Views: 239

Answers (2)

Gean Ribeiro
Gean Ribeiro

Reputation: 1045

You can listen the EntityStats event's in Entity constructor and dispatch a Entity event's. Like this:

public class Entity : INotifyPropertyChanged
{
    public event PropertyChangedEventHandler PropertyChanged;

    public Entity() {
        Stats.PropertyChanged += Stats_PropertyChanged
    }
    //Other stuff.... 

    void Stats_PropertyChanged(object sender, PropertyChangedEventArgs e)
    {
        if (PropertyChanged != null)
        {
            e.PropertyName = "Stats." + e.PropertyName;
            PropertyChanged(this, e);
        }
    }
}

Now, in the RegisterEntity, the listener method can be associated direct to the Entity instance:

public void RegisterEntity(Entity entity)
{            
    entity.PropertyChanged += entity_PropertyChanged;           
}

and the sender of the listener method is Entity instance, but is possible identify if the property was changed in Stats property:

void entity_PropertyChanged(object sender, PropertyChangedEventArgs e)
{
    if (e.PropertyName == "Stats.CurrentHealth")
    {
        Message.Write("Stats.CurrentHealth property changed!");
        DeathCheck((Entity)sender);
    }
}

Upvotes: 4

adv12
adv12

Reputation: 8551

You could give the EntityStats class a property named Entity (or somesuch) and set that property in the EntityStats constructor:

public class Entity : INotifyPropertyChanged
{
    public string Name { get; set; }
    public EntityRole Role { get; set; }         
    public EntityStats Stats = new EntityStats(this);
    //Other stuff.... 
}

public class EntityStats : INotifyPropertyChanged
{
    private Entity _entity;

    public Entity Entity
    {
        get { return _entity; }
    }

    public EntityStats(Entity entity)
    {
        _entity = entity;
    }

    // ...
}

Upvotes: 1

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