Squashed 'FSI.Lib/' content from commit dceb500

git-subtree-dir: FSI.Lib
git-subtree-split: dceb5008a2176c2b8ab5e55a73b1c25d31a7f841

FSI.Lib/MVVM/ViewModelBase.cs

@@ -0,0 +1,61 @@
+using System.ComponentModel;
+using System.Runtime.CompilerServices;
+
+/* Example for use:
+  
+public class MyViewModel : ViewModelBase
+{
+    private int myProperty;
+    public int MyProperty
+    {
+        get { return myProperty; }
+        set { SetProperty(ref myProperty, value);
+    }
+}
+
+*/
+
+
+namespace FSI.Lib.MVVM
+{
+    public class ViewModelBase : INotifyPropertyChanged
+    {
+        /// <summary>
+        /// Multicast event for property change notifications.
+        /// </summary>
+        public event PropertyChangedEventHandler PropertyChanged;
+
+        /// <summary>
+        /// Checks if a property already matches the desired value.  Sets the property and
+        /// notifies listeners only when necessary.
+        /// </summary>
+        /// <typeparam name="T">Type of the property.</typeparam>
+        /// <param name="storage">Reference to a property with both getter and setter.</param>
+        /// <param name="value">Desired value for the property.</param>
+        /// <param name="propertyName">Name of the property used to notify listeners.This
+        /// value is optional and can be provided automatically when invoked from compilers that
+        /// support CallerMemberName.</param>
+        /// <returns>True if the value was changed, false if the existing value matched the
+        /// desired value.</returns>
+        protected virtual bool SetProperty<T>(ref T storage, T value, [CallerMemberName] string propertyName = null)
+        {
+            if (object.Equals(storage, value)) return false;
+            storage = value;
+            // Log.DebugFormat("{0}.{1} = {2}", this.GetType().Name, propertyName, storage);
+            this.OnPropertyChanged(propertyName);
+            return true;
+        }
+
+
+        /// <summary>
+        /// Notifies listeners that a property value has changed.
+        /// </summary>
+        /// <param name="propertyName">Name of the property used to notify listeners.  This
+        /// value is optional and can be provided automatically when invoked from compilers
+        /// that support <see cref="CallerMemberNameAttribute"/>.</param>
+        protected virtual void OnPropertyChanged([CallerMemberName] string propertyName = null)
+        {
+            this.PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
+        }
+    }
+}