Question

I want to extract common code from a few WinRT components to one base class so I don’t need to copy&past it. I have the following base class:

[Windows::Foundation::Metadata::WebHostHidden]
ref class ExpandableView : public Windows::UI::Xaml::DependencyObject
{
public:
    static void onIsExpandedChanged(Windows::UI::Xaml::DependencyObject^ object, 
        Windows::UI::Xaml::DependencyPropertyChangedEventArgs^ arguments);
public:
    property bool IsExpanded
    {
        bool get(){return (bool)GetValue(IsExpandedProperty);}
        void set(bool value){SetValue(IsExpandedProperty, value);}
    }
    static property Windows::UI::Xaml::DependencyProperty^ IsExpandedProperty
    {
        Windows::UI::Xaml::DependencyProperty^ get(){return  _IsExpandedProperty;}
    }
protected:
    ExpandableView();
    virtual void viewExpanded();
    virtual void viewCollapsed();
private:
    void _expand();
    void _collapse();
private:
    static Windows::UI::Xaml::DependencyProperty^ _IsExpandedProperty;
};

And I create a few User Controls which should be somehow inherited from this base class. And it is not possible to do it the way I want because winrt class can inherit only one ref class and other should be interfaces. But I need this very class which has dependency property which has some logic when it is set and I don’t want to copy&past this property across all my classes.
So the question is: how to achieve it with WinRT?

Answer 1

Have you tried using a template and inheritance of the specific class needed:

template<typename BaseClass>
ref class ExpandableView : public BaseClass;

Now the subclasses reusing ExpandableView can inherit whatever they need, not only Windows::UI::Xaml::DependencyObject.