title: Communication between viewmodels piggybacking off of the iNotifyPropertyChanged system
body: <p>I am using MVVM and I would like to communicate between viewmodels. I have a user control that contains another user control inside it, and I would like the parent usercontrol to run some code when a property in the child is changed. I have seen several ways to communicate between viewmodels, such as using MVVM Light Messenger, or PRISM Event Aggregator, but I was hoping there was some way to accomplish this simply by somehow subscribing to the <code>PropertyChanged</code> event raised through the <code>INotifyPropertyChanged</code> implementation.</p>
  
  <p>There is an answer by Matt Hamilton in <a href="https://stackoverflow.com/questions/7882393/co-opting-binding-to-listen-to-propertychanged-events-without-a-frameworkelement" title="stack overflow question">this post</a> but I have trouble implementing it because it needs a DependencyObject, and my ViewModels are POCOs rather than DOs</p>
  
  <p>Is there some way of using the <code>INotifyPropertyChanged</code> system, as I would prefer to not have to implement a messaging system. If not is a messaging system the best? I also saw an example where some guy just used the code behind of the view to help pass the property, however I don't want to break the MVVM pattern as I wanna do some testing at a later stage.</p>