.net - Can't subscribe to DelegateCommand.CanExecuteChanged -

I have two ViewModels and one of them is second in the Microsoft. Practice. Prism Commands Delayed Commands is called PrintCommand . This part of the order of CanExecuteChanged desirable to subscribe to the event has always been applied like:

  OneViewModel.PrintCommand.CanExecuteChanged + = CanExecuteChangedHandler;  

The problem is that this membership does not work. Decompiled CanExecuteChanged looks like this:

  public function eventhandler CanExecuteChanged {{add WeakEventHandlerManager.AddWeakReferenceHandler (reference this._canExecuteChangedHandlers, value, 2); } Remove {WeakEventHandlerManager.RemoveWeakReferenceHandler (this._canExecuteChangedHandlers, value); }}  

When I pause a live operators after a couple of after debug, subscription steps _canExecuteChangedHandlers , even if the client object still exists Does not seem to have
I'm curious, why is this happening?

After the text "itemprop =" text ">

the answer was found in the description of CanExecuteChanged . The message is:

  /// when subscribing & lt to see cref = "e: System.Windows.Input.ICommand.CanExecuteChanged" / & gt; Event using the /// code (when binding on using XML) will require a hard reference for the event handler. This is to stop the /// garbage collection of the event handler because the command implements weak event patterns, so this is not a difficult reference for /// this handler. The example implementation can be seen in composite commands and commandbackbusiness /// sections. In most scenarios, there is no reason to sign up directly at the Kenxaxite changelog event, but if you do, then you are responsible for maintaining /// reference.  

That means we have to be a difficult context:

  private Reedonli Iventhaandlr Kmmandaksaksaktekcanghedlr;  

and thus use it:

  this.commandCanExecuteChangedHandler = new eventhandler (this.CommandCanExecuteChanged); This.command.CanExecuteChanged + = this.commandCanExecuteChangedHandler;