访问父级对象

Question

public class Activity
{
    public games _Games {get;set;}
    public sports _Sports {get;set;}
}

public class games : PropertyChangedBase
{
    public int player
    { 
        get;
        set; //have if- else statement
    }
}

public class sports : PropertyChangedBase
{
     public int sub{get;set;}
}

Aim: when the games player is more than 2, I would like to update sports sub variable to 10.

Question: How can I access the parent class and update the sports class variable?

Answer 1

You need to create an instance of Activity . You also need to initialize _Sports in it

Activity activity = new Activity();
activity._Sports = new sports();
activity._Sports.sub = 10;

Or using object tantalizer

Activity activity = new Activity
{
    _Sports = new sports()
};

activity._Sports.sub = 10;

By the way, Activity is not parent class of sports . Activity holds sports object as a member. In your example PropertyChangedBase is parent class of games .

Answer 2

You could use an event that would signal to the Activity class that it is time to update.

public class games
{
    public event UpdatePlayerSubDelegate UpdatePlayerSub;

    public delegate void UpdatePlayerSubDelegate();
    private int _player;

    public int player
    {
        get { return _player; }
        set
        {
            _player = value;
            if (_player > 2)
            {
                // Fire the Event that it is time to update
                UpdatePlayerSub();
            }                
        }
    }          
}

In the Activity class you can register the event in the constructor and write in to the event handler the necessary update. In your case sub to 10:

public class Activity
{
    public games _Games { get; set; }
    public sports _Sports { get; set; }

    public Activity()
    {
        this._Games = new games();
        this._Games.UpdatePlayerSub += _Games_UpdatePlayerSub;
        this._Sports = new sports();
    }

    private void _Games_UpdatePlayerSub()
    {
        if (_Sports != null)
        {
            _Sports.sub = 10;
        }
    }
}

EDIT I just saw the tag INotifyPropertyChanged . Of course you could also use this interface and the provided event. Implement the interface as the following:

public class games : INotifyPropertyChanged
{
    public event PropertyChangedEventHandler PropertyChanged;

    private int _player;
    public int player
    {
        get { return _player; }
        set
        {
            _player = value;
            if (_player > 2)
            {
                // Fire the Event that it is time to update
                PropertyChanged(this, new PropertyChangedEventArgs("player"));
            }                
        }
    }          
}

And in the Activity class register again to the event in the constructor:

public Activity()
{
    this._Games = new games();
    this._Games.PropertyChanged += _Games_PropertyChanged;
    this._Sports = new sports();
}

and declare the body of the event handler:

private void _Games_PropertyChanged(object sender, PropertyChangedEventArgs e)
{
    if (_Sports != null)
    {
        _Sports.sub = 10;
    }
}

And _Sports.sub will get updated automatically. Hope it helps. There are of course other ways to accomplish this update. It is just the first the came to my mind