INotifyPropertyChanged in C++/CLI

Question

 

When I implement INotifyPropertyChanged  in C++/CLI:

(public ref class Task : public INotifyPropertyChanged)

A problem comes to me:

Error 3 error C3766: 'SomeData' must provide an implementation for the interface method 'void System::ComponentModel::INotifyPropertyChanged::PropertyChanged::add(System::ComponentModel::PropertyChangedEventHandler ^)' 

I don't know why this error doesn't occur in C# when I implement the INotifyPropertyChanged  ,but occur in C++/CLI .

Could you so kind to tell me how to resolve it?

Thank you very much!

Answer 1

No one knows?

Answer 2

Did you implement the event? This works for me:

public ref class Class1 : INotifyPropertyChanged
{
    public:
        virtual event PropertyChangedEventHandler^ PropertyChanged;
};

Answer 3

But this does not work:

public ref class Class1 : INotifyPropertyChanged
{
    public:
        virtual event PropertyChangedEventHandler^ PropertyChanged;

  void OnPropertyChanged(String^ info)
  { 
     PropertyChangedEventHandler^ handler= PropertyChanged;//error
           if (handler != nullptr)
           {
              handler(this, gcnew PropertyChangedEventArgs(info));
           }
  }

};

error C3918: usage requires "Task::PropertyChanged' to be a data member 

Answer 4

In C++ you don't need to check if the handler is null so the following should work:

void OnPropertyChanged(String^ info)
{
    PropertyChanged(this, gcnew PropertyChangedEventArgs(info));
}

Answer 5

Thank you very much