How to achieve INotifyPropertyChanged functionality for the values in a bool[]?

Question

I have a bool array of size 4 and I want to bind each cell to a different control. This bool array represents 4 statuses (false = failure, true = success). This bool array is a propery with a class:

class foo : INotifyPropertyChanged {
...
private bool[] _Statuses;
public bool[] Statuses
{
    get {return Statuses;}
    set {
            Statuses = value;
            OnPropertyChanged("Statuses");
        }
}

In XAML there are 4 controls, each one bound to one cell of the array:

... Text="{Binding Path=Statuses[0]}" ...
... Text="{Binding Path=Statuses[1]}" ...
... Text="{Binding Path=Statuses[2]}" ...
... Text="{Binding Path=Statuses[3]}" ...

The problem is that the notify event is raised only when I change the array itself and isn't raised when I change one value within the array, i.e, next code line raises the event:

Statuses = new bool[4];

but next line does not raises the event:

Statuses [0] = true;

How can I raise the event each time one cell is changed?

Answer 1

You need to expose your statuses as an indexer, then raise a property change event that indicates that the indexer has changed.

private bool[] _Statuses;

public bool this[int index]
{
    get { return _Statuses[index]; }
    set
    {
        _Statuses[index] = value;

        if (PropertyChanged != null)
            PropertyChanged(this, new PropertyChangedEventArgs(Binding.IndexerName));
    }
}

See this blog post:

http://10rem.net/blog/2010/03/08/wpf---silverlight-quick-tip-inotifypropertychanged-for-indexer