[boost] Re: Java style GUI in C++

From: Edward Diener (eddielee_at_[hidden])
Date: 2004-08-18 19:35:34

Reece Dunn wrote:
> John Torjo wrote:
>> Hi Reece,
>>> [3] The support for events via "listeners". This will most likely be
>>> geared towards key/mouse events and "action" events (e.g. when the
>>> user presses on a button).
>>
>> I'm not a big fan of listeners. You need to do a lot of coding
>> manually to set them, etc. I've implemented them totally different -
>> using event handler classes.
>
> My idea was something along the lines of:
>
> class MouseEvent
> {
>    public:
>       static const int                 LeftButton   = 0;
>       static const int                 MiddleButton = 1;
>       static const int                 RightButton  = 2;
>    private:
>       int                              button;
>       unsigned int                     vkeys;
>       win::api::point                  pt;
>    public:
>       inline                 MouseEvent( int, WPARAM, LPARAM );
> };
>
> MouseEvent::MouseEvent( int btn, WPARAM wp, LPARAM lp ):
>    button( btn ),
>    vkey(   wp ),
>    pt(     lp )
> {
> }
>
> class MouseListener
> {
>    public:
>       virtual void                               mouseMove(
> const MouseEvent & );
>       virtual void                               mouseButtonDown(
> const MouseEvent & );
>       virtual void                               mouseButtonUp(
> const MouseEvent & );
>       virtual void
> mouseButtonDoubleClick( const MouseEvent & );
>    public:
>       virtual               ~MouseButtonListener();
> };
>
> With a common listener interface for GUI object actions, e.g.
> pressing a mouse button, selecting an item in a listbox, editing
> text, etc.

Why not use boost::signals for your event interface. It is much better than
hand-coded actions and listeners, since any type of function can handle an
event. The technology is already in Boost so why re-invent the wheel.