ViewModel2.cs

/// <summary>
/// <see cref="DependencyOnModelPropertyAttribute"/> が指定されたプロパティの変更通知を有効化します。
/// </summary>
protected void EnableAutoPropertyChangedEvent(INotifyPropertyChanged model)
{
    PropertyChangedEventListener listener = null;

    foreach (var prop in this.GetType().GetProperties(BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.Instance))
    {
        PropertyChangedEventHandler handler = null;
        foreach (var attr in prop.GetCustomAttributes<DependencyOnModelPropertyAttribute>())
        {
            if (listener == null) listener = new PropertyChangedEventListener(model);
            if (handler == null) handler = CreateHandler(prop.Name);

            listener.Add(attr.DependentPropertyName, handler);
        }
    }

    if (listener != null) this.CompositeDisposable.Add(listener);

    PropertyChangedEventHandler CreateHandler(string propertyName) => (_, __) => this.RaisePropertyChanged(propertyName);
}