Many new plays

BaseViewModel.cs

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+using System.Collections.Generic;
+using System.ComponentModel;
+using System.Runtime.CompilerServices;
+using ModernWpfPlayground.Annotations;
+
+namespace ModernWpfPlayground
+{
+    public abstract class BaseViewModel : INotifyPropertyChanged
+    {
+        private readonly Dictionary<string, object> _valueDict = new Dictionary<string, object>();
+
+        protected bool SetProperty<T>(T value, [CallerMemberName] string propertyName = null)
+        {
+            if (_valueDict.TryGetValue(propertyName, out var obj) && Equals(value, obj)) return false;
+
+            _valueDict[propertyName] = value;
+            OnPropertyChanged(propertyName);
+            return true;
+        }
+
+        protected T GetProperty<T>(T defaultValue = default, [CallerMemberName] string propertyName = null)
+        {
+            return _valueDict.TryGetValue(propertyName, out var obj) ? (T) obj : defaultValue;
+        }
+
+        public event PropertyChangedEventHandler PropertyChanged;
+
+        [NotifyPropertyChangedInvocator]
+        [PublicAPI]
+        protected virtual void OnPropertyChanged([CallerMemberName] string propertyName = null)
+        {
+            PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
+        }
+
+    }
+}