WPF Dependency Property Question

I'm new to WPF, and I'm trying to do what I thought would be a simple task - display the value of a field in my business object as it changes during my program. I know how to "force" it to change by manually changing the TextBox.Text property in C#, but as I'm learning WPF I want to do it the "right" way, and that means databinding.

Question #1: As far as I understand it, my choice is to either use a DependencyProperty or implement INotifyPropertyChanged in my business object, right?

Question #2: Here is a generic version of my code in which I attempted to go the DependencyProperty route.

Markup:

Button x:Name="nextButton" Content="Click"  Grid.Row="2" Click="nextButton_Click" />
TextBox x:Name="myTextBox" Grid.Row="1" Text="{Binding Source=myTest, Path=Name, UpdateSourceTrigger=PropertyChanged, NotifyOnSourceUpdated=True}"/>

Code-Behind:

namespace DependencyTest2
{
    /// 
    /// Interaction logic for MainWindow.xaml
    /// 
    public partial class MainWindow : Window
    {
        private int i;

        private TestSphere myTest;

        public MainWindow()
        {
            InitializeComponent();

            i = 0;

            myTest = new TestSphere();
        }

        private void nextButton_Click(object sender, RoutedEventArgs e)
        {
            switch (i)
            {
                case 0:
                    myTest.Name = "string1";
                    break;
                case 1:
                    myTest.Name = "string2";
                    break;
                case 2:
                    myTest.Name = "string3";
                    break;
            }

            i++;
        }
    }

    class TestSphere : DependencyObject
    {

        public string Name
        {
            get { return (string)GetValue(NameProperty); }
            set { SetValue(NameProperty, value); }
        }

        public static readonly DependencyProperty NameProperty =
            DependencyProperty.Register("Name", typeof(string), typeof(TestSphere));


        public TestSphere()
        {
            Name = "default";
        }
    }
}

When I run the program, nothing appears in text box, even though the bound property has a value - is there something else I need to do to alert the binding that the source value has changed? I thought that using a DependencyProperty as the source would take care of that, but then again, I'm a WPF rookie. Thanks!

• Steve

Ok, I tried to implement INotifyPropertyChanged using a wrapper class I found on codeproject as follows:

    class TestSphere : NotifyProperyChangedBase
    {
        private string _Name;

        public string Name
        {
            get { return _Name; }
            set 
            {
                this.CheckPropertyChanged("Name", ref _Name, ref value);
            }
        }

        public TestSphere()
        {
            Name = "default";
        }
    }

    public abstract class NotifyProperyChangedBase : INotifyPropertyChanged
    {
        #region INotifyPropertyChanged Members
        public event PropertyChangedEventHandler PropertyChanged;
        #endregion
        #region methods
        protected bool CheckPropertyChanged(string propertyName, ref T oldValue, ref T newValue)
        {
            if (oldValue == null && newValue == null)
            {
                return false;
            }

            if ((oldValue == null && newValue != null) || !oldValue.Equals((T)newValue))
            {
                oldValue = newValue;
                FirePropertyChanged(propertyName);
                return true;
            }

            return false;
        }

        protected void FirePropertyChanged(string propertyName)
        {
            if (this.PropertyChanged != null)
            {
                this.PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
            }
        }

        #endregion

Here is my new Markup, too:

    Grid Name="myGrid">
        Grid.RowDefinitions>
            RowDefinition Height="30"/>
            RowDefinition Height="30"/>
            RowDefinition Height="30"/>
            RowDefinition Height="*"/>
        /Grid.RowDefinitions>
        Label x:Name="myLabel" Grid.Row="0" Foreground="Black"  />
        Button x:Name="nextButton" Content="Click"  Grid.Row="2" Click="nextButton_Click" />
        TextBox x:Name="myTextBox" Grid.Row="1" Text="{Binding Path=myTest.Name}"/>
    /Grid>

I also added the line myGrid.DataContext = myTest; to 'public MainWindow()' immediately after I instantiate myTest. When I step through the resulting program, the value of this.PropertyChanged always evaluates to null, so that the PropertyChanged even never fires. Sorry in advance for what must be a really noob question.

• Steve