Other unrelated option:
"bloated" widget class with templated calback functions.
This obviously should not be a part of the fltk library but I leave this
template as an example for the "reach callback" possibility with
templated widget and special My_Callback functor class:
------------------------------------------------------
template <typename WIDGET>
class Fl_Callback_Widget: public WIDGET{
bool is_my_callback;
void delete_previous_callback(){
if(is_my_callback){
delete ((My_Callback *)user_data());
is_my_callback = 0;
}
}
public:
template <typename T1, ....>
void callback(T1 t1, ...){
delete_previous_callback()
Fl_Widget::callback(&my_special_callback_function,
new My_Callback(t1, ....));
~Fl_Callback_Widget(){
delete_previous_callback();
}
// other temples for callback functions
// ie with different numbers of parameters
...
// All possible constructors with all possible number of parameters:
Fl_Callback_Widget():WIDGET(), is_my_callback(0){}
template <typename T1>
Fl_Callback_Widget(T1 t1):WIDGET(t1), is_my_callback(0){}
template <typename T1, typename T2>
Fl_Callback_Widget(T1 t1, T2 t2):WIDGET(t1, t2), is_my_callback(0){}
template <typename T1, typename T2, typemname T3>
Fl_Callback_Widget(T1 t1,T2 t2,T3 t3):
WIDGET(t1,t2,t2), is_my_callback(0){}
// ... and so on to - say 7 parameters
// to accomodate for all possible widget constructors
}
// Single special callback for My_Callback functors:
void my_callback(Fl_Widget * w, void * data){
(My_Callback *)
}
--------------------------------------------------------------
The advantage of this solution is tat it is an add-on (no changes to the
library) and you can use this template like ANY other widget but you
have this extra reach callback system:
Fl_Callback_Widget<Fl_Browser> browser(x, y, w, h, "My browser");
browser.callback(some_class,&Some_Class::method,argument_value_pointer);
The disadvantage is bloat - for each used widget class there is new
specialization of the template class.
R.
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