Added some helper classes for INotifyPropertyChanged; added unit tests for the ObservableSet class; documented the second Count property exposed by the multi dictionary

git-svn-id: file:///srv/devel/repo-conversion/nusu@262 d2e56fa2-650e-0410-a79f-9358c0239efd

Source/ObservableHelper.cs

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+#region CPL License
+/*
+Nuclex Framework
+Copyright (C) 2002-2012 Nuclex Development Labs
+
+This library is free software; you can redistribute it and/or
+modify it under the terms of the IBM Common Public License as
+published by the IBM Corporation; either version 1.0 of the
+License, or (at your option) any later version.
+
+This library is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+IBM Common Public License for more details.
+
+You should have received a copy of the IBM Common Public
+License along with this library
+*/
+#endregion
+
+using System;
+#if !NO_LINQ_EXPRESSIONS
+using System.Linq.Expressions;
+#endif
+
+namespace Nuclex.Support {
+
+  /// <summary>Contains helper methods for observing property changed</summary>
+  public static class ObservableHelper {
+
+#if !NO_LINQ_EXPRESSIONS
+    /// <summary>Obtains the name of a property from a lambda expression</summary>
+    /// <param name="property">
+    ///   Lambda expression for the property whose name will be returned
+    /// </param>
+    /// <returns>The name of the property contained in the lamba expression</returns>
+    /// <remarks>
+    ///   <para>
+    ///     This method obtains the textual name of a property specified in a lambda
+    ///     expression. By going through a lambda expression, the property will be
+    ///     stated as actual code, allowing F2 refactoring to correctly update any
+    ///     references to the property when it is renamed.
+    ///   </para>
+    ///   <example>
+    ///     <code>
+    ///       string propertyName = ObservableHelper.GetPropertyName(() => SomeValue);
+    ///       Assert.AreEqual("SomeValue", propertyName);
+    ///     </code>
+    ///   </example>
+    /// </remarks>
+    public static string GetPropertyName<TValue>(Expression<Func<TValue>> property) {
+      var lambda = (LambdaExpression)property;
+
+      MemberExpression memberExpression;
+      {
+        var unaryExpression = lambda.Body as UnaryExpression;
+        if(unaryExpression != null) {
+          memberExpression = (MemberExpression)unaryExpression.Operand;
+        } else {
+          memberExpression = (MemberExpression)lambda.Body;
+        }
+      }
+
+      return memberExpression.Member.Name;
+    }
+#endif // !NO_LINQ_EXPRESSIONS
+
+  }
+
+} // namespace Nuclex.Support