Thread: templates and listeners

does any one has any good ideas to solve this problem.

I have a base window class that is called GfxWindow that generates a number of events. These events are given notifications within the GfxWindowListener class.

Code:

class GfxWindowListener
{
public:
    virtual void ModifiedTitle(GfxWindow* window,
                                 const std::string& str) = 0;
    virtual void DeleteWindow(GfxWindow* window) = 0;

    virtual void Select(GfxWindow* window) = 0;
    virtual void UnSelect(GfxWindow* window) = 0;
    virtual void Select2(GfxWindow* window) = 0;
};

I then create adapter classes which will be used to derive from

Code:

class GfxInfoAdapter : public GfxWindowListener
{
public:
    virtual void OnSelect(GfxWindow* window)
    {

    }

    virtual void OnUnSelect(GfxWindow* window)
    {

    }

    virtual void OnSelect2(GfxWindow* window)
    {

    }
};

class GfxSelectAdapter : public GfxWindowListener
{   
public:
    virtual void ModifiedTitle(GfxWindow* window,
                               const std::string& str) 
    {

    }

    virtual void DeleteWindow(GfxWindow* window) 
    { 
    
    }
};

The problem is that GfxWindow will be derived from GfxListBox that will have its own set of events. I could do something like

Code:

class GfxListBoxListener : public GfxWindowListener

but this would mean that cilent programers would not be able to use the GfxWindow adapter class. Thus, I do something like

Code:

template<class GFX_WINDOW_LISTENER = GfxWindowListener>
class GfxListBoxListener : public GFX_WINDOW_LISTENER
{
public:
    typedef long int SizeType;
    
    // when the user has requested to insert a string
    virtual void RequestInsertString(GfxListBox* lb,
                                     SizeType place) = 0;

    virtual void InsertString(GfxListBox* lb,
                              const std::string& str, 
                              SizeType place) = 0;

    virtual void AddString(GfxListBox* lb,
                           const std::string& str) = 0;

    virtual void ReplaceString(GfxListBox* lb,
                               SizeType item, 
                               const std::string& str) = 0;

    virtual void DeleteItem(GfxListBox* lb, SizeType item) = 0;

};

Is this a good thing or should I create separate adapters for GfxListBox?

Ok, I think I solved the problem I was having with the design.