--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/FingersDance.ViewModel/ViewModelBase.cs	Tue Sep 15 13:30:58 2009 +0200
@@ -0,0 +1,127 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.ComponentModel;
+using System.Diagnostics;
+
+namespace FingersDance.ViewModel
+{
+    /// <summary>
+    /// Base class for all ViewModel classes in the application.
+    /// It provides support for property change notifications 
+    /// and has a DisplayName property.  This class is abstract.
+    /// </summary>
+    public abstract class ViewModelBase : INotifyPropertyChanged, IDisposable
+    {
+        #region Constructor
+
+        protected ViewModelBase()
+        {
+        }
+
+        #endregion // Constructor
+
+        #region DisplayName
+
+        /// <summary>
+        /// Returns the user-friendly name of this object.
+        /// Child classes can set this property to a new value,
+        /// or override it to determine the value on-demand.
+        /// </summary>
+        public virtual string DisplayName { get; protected set; }
+
+        #endregion // DisplayName
+
+        #region Debugging Aides
+
+        /// <summary>
+        /// Warns the developer if this object does not have
+        /// a public property with the specified name. This 
+        /// method does not exist in a Release build.
+        /// </summary>
+        [Conditional("DEBUG")]
+        [DebuggerStepThrough]
+        public void VerifyPropertyName(string propertyName)
+        {
+            // Verify that the property name matches a real,  
+            // public, instance property on this object.
+            if (TypeDescriptor.GetProperties(this)[propertyName] == null)
+            {
+                string msg = "Invalid property name: " + propertyName;
+
+                if (this.ThrowOnInvalidPropertyName)
+                    throw new Exception(msg);
+                else
+                    Debug.Fail(msg);
+            }
+        }
+
+        /// <summary>
+        /// Returns whether an exception is thrown, or if a Debug.Fail() is used
+        /// when an invalid property name is passed to the VerifyPropertyName method.
+        /// The default value is false, but subclasses used by unit tests might 
+        /// override this property's getter to return true.
+        /// </summary>
+        protected virtual bool ThrowOnInvalidPropertyName { get; private set; }
+
+        #endregion // Debugging Aides
+
+        #region INotifyPropertyChanged Members
+
+        /// <summary>
+        /// Raised when a property on this object has a new value.
+        /// </summary>
+        public event PropertyChangedEventHandler PropertyChanged;
+
+        /// <summary>
+        /// Raises this object's PropertyChanged event.
+        /// </summary>
+        /// <param name="propertyName">The property that has a new value.</param>
+        protected virtual void OnPropertyChanged(string propertyName)
+        {
+            this.VerifyPropertyName(propertyName);
+
+            PropertyChangedEventHandler handler = this.PropertyChanged;
+            if (handler != null)
+            {
+                var e = new PropertyChangedEventArgs(propertyName);
+                handler(this, e);
+            }
+        }
+
+        #endregion // INotifyPropertyChanged Members
+
+        #region IDisposable Members
+
+        /// <summary>
+        /// Invoked when this object is being removed from the application
+        /// and will be subject to garbage collection.
+        /// </summary>
+        public void Dispose()
+        {
+            this.OnDispose();
+        }
+
+        /// <summary>
+        /// Child classes can override this method to perform 
+        /// clean-up logic, such as removing event handlers.
+        /// </summary>
+        protected virtual void OnDispose()
+        {
+        }
+
+#if DEBUG
+        /// <summary>
+        /// Useful for ensuring that ViewModel objects are properly garbage collected.
+        /// </summary>
+        ~ViewModelBase()
+        {
+            string msg = string.Format("{0} ({1}) ({2}) Finalized", this.GetType().Name, this.DisplayName, this.GetHashCode());
+            System.Diagnostics.Debug.WriteLine(msg);
+        }
+#endif
+
+        #endregion // IDisposable Member
+    }
+}