Re: EventBox and bind combination

[Bob Caryl <bob fis-cal com>]

Strictly speaking, you're probably right about the <const char *>
business.  I assumed that he would not be passing literals as a matter
of course.

I am curious, however, about the negative one <-1> you indicate prior to
the <const char *> parameter:  Could you amplify?

Thanks,

Bob Caryl

On Thu, 2005-02-03 at 16:49, Murray Cumming wrote:
> On Thu, 2005-02-03 at 16:24 -0600, Bob Caryl wrote:
> > Your problem is that you neglected to indicate to the template what
> > sort of value you were passing, i.e.
> > 
> > m_EventBox.signal_button_press_event().connect(sigc::bind<char
> > *>(sigc::mem_fun(*this,&ExampleWindow::button_press), "testing"));
> 
> I'm not quite sure whether that should work with libsigc++ 2. 
> sigc::bind<-1, const char*> should work. A Glib::ustring would be better
> too.
> 
> > 
> > Give that a try... 
> > 
> > Cheers!
> > 
> > Bob Caryl 
> > On Thu, 2005-02-03 at 15:41, Pete S wrote: 
> > > Hello,
> > > 
> > > I've been programming with gtkmm for a little while
> > > and I really enjoy it.  I was wondering if any of you
> > > might have suggestions on how to overcome the
> > > following hurdle:
> > > 
> > > I'm trying to pass a parameter into a on_button_press
> > > function as follows:
> > > <begin code>
> > > m_EventBox.signal_button_press_event().connect(sigc::bind(sigc::mem_fun(*this,
> > > &ExampleWindow::button_press), "testing") );
> > > <end code>
> > > 
> > > with button_press() being defined as follows:
> > > <begin code>
> > > //eventbox.h file
> > > class ExampleWindow {
> > > ...
> > > bool button_press(GdkEventButton *e, char *t);
> > > ...
> > > };
> > > 
> > > //eventbox.cc file
> > > bool ExampleWindow::button_press(GdkEventButton*, char
> > > *t);
> > > {
> > > cout<<t<<"\n";
> > > return true;
> > > }
> > > 
> > > <end code>
> > > 
> > > If I decide not to use sigc::bind and remove the char
> > > *t from button_press(), it compiles and works fine,
> > > but I need to know how to pass a parameter when the
> > > EventBox press button signal is emitted.
> > > 
> > > Here's what the compilation output looks like:
> > > <begin comp output>
> > > $ make -f eventbox.mak 
> > > g++ -g `pkg-config gtkmm-2.4 --cflags --libs` -o
> > > eventbox eventbox.cc eventboxmain.cc -L/usr/local/lib
> > > -pthread 
> > > /usr/local/include/sigc++-2.0/sigc++/adaptors/adaptor_trait.h:
> > > In member function `typename
> > > sigc::adaptor_functor<T_functor>::deduce_result_type<T_arg1,
> > > T_arg2, void, void, void, void, void>::type
> > > sigc::adaptor_functor<T_functor>::operator()(T_arg1,
> > > T_arg2) const [with T_arg1 = GdkEventButton* const&,
> > > T_arg2 = Glib::ustring&, T_functor =
> > > sigc::bound_mem_functor2<bool, ExampleWindow,
> > > GdkEventButton*, char*>]':
> > > /usr/local/include/sigc++-2.0/sigc++/adaptors/bind.h:1121:
> > >   instantiated from `typename
> > > sigc::bind_functor<-0x000000001, T_functor, T_type1,
> > > sigc::nil, sigc::nil, sigc::nil, sigc::nil, sigc::nil,
> > > sigc::nil>::deduce_result_type<T_arg1, void, void,
> > > void, void, void, void>::type
> > > sigc::bind_functor<-0x000000001, T_functor, T_type1,
> > > sigc::nil, sigc::nil, sigc::nil, sigc::nil, sigc::nil,
> > > sigc::nil>::operator()(T_arg1) [with T_arg1 =
> > > GdkEventButton* const&, T_functor =
> > > sigc::bound_mem_functor2<bool, ExampleWindow,
> > > GdkEventButton*, char*>, T_type1 = Glib::ustring]'
> > > /usr/local/include/sigc++-2.0/sigc++/functors/slot.h:136:
> > >   instantiated from `static T_return
> > > sigc::internal::slot_call1<T_functor, T_return,
> > > T_arg1>::call_it(sigc::internal::slot_rep*, typename
> > > sigc::type_trait<T_arg3>::take) [with T_functor =
> > > sigc::bind_functor<-0x000000001,
> > > sigc::bound_mem_functor2<bool, ExampleWindow,
> > > GdkEventButton*, char*>, Glib::ustring, sigc::nil,
> > > sigc::nil, sigc::nil, sigc::nil, sigc::nil,
> > > sigc::nil>, T_return = bool, T_arg1 =
> > > GdkEventButton*]'
> > > /usr/local/include/sigc++-2.0/sigc++/functors/slot.h:144:
> > >   instantiated from `static void*(*
> > > sigc::internal::slot_call1<T_functor, T_return,
> > > T_arg1>::address())(void*) [with T_functor =
> > > sigc::bind_functor<-0x000000001,
> > > sigc::bound_mem_functor2<bool, ExampleWindow,
> > > GdkEventButton*, char*>, Glib::ustring, sigc::nil,
> > > sigc::nil, sigc::nil, sigc::nil, sigc::nil,
> > > sigc::nil>, T_return = bool, T_arg1 =
> > > GdkEventButton*]'
> > > /usr/local/include/sigc++-2.0/sigc++/functors/slot.h:524:
> > >   instantiated from `sigc::slot1<T_return,
> > > T_arg1>::slot1(const T_functor&) [with T_functor =
> > > sigc::bind_functor<-0x000000001,
> > > sigc::bound_mem_functor2<bool, ExampleWindow,
> > > GdkEventButton*, char*>, Glib::ustring, sigc::nil,
> > > sigc::nil, sigc::nil, sigc::nil, sigc::nil,
> > > sigc::nil>, T_return = bool, T_arg1 =
> > > GdkEventButton*]'
> > > /usr/local/include/sigc++-2.0/sigc++/functors/slot.h:1129:
> > >   instantiated from `sigc::slot<T_return, T_arg1,
> > > sigc::nil, sigc::nil, sigc::nil, sigc::nil, sigc::nil,
> > > sigc::nil>::slot(const T_functor&) [with T_functor =
> > > sigc::bind_functor<-0x000000001,
> > > sigc::bound_mem_functor2<bool, ExampleWindow,
> > > GdkEventButton*, char*>, Glib::ustring, sigc::nil,
> > > sigc::nil, sigc::nil, sigc::nil, sigc::nil,
> > > sigc::nil>, T_return = bool, T_arg1 =
> > > GdkEventButton*]'
> > > eventbox.cc:37:   instantiated from here
> > > /usr/local/include/sigc++-2.0/sigc++/adaptors/adaptor_trait.h:103:
> > > error: no match for call to
> > > `(sigc::bound_mem_functor2<bool, ExampleWindow,
> > > GdkEventButton*, char*>) (GdkEventButton* const&,
> > > Glib::ustring&)'
> > > /usr/local/include/sigc++-2.0/sigc++/functors/mem_fun.h:1897:
> > > note: candidates are: T_return
> > > sigc::bound_mem_functor2<T_return, T_obj, T_arg1,
> > > T_arg2>::operator()(typename
> > > sigc::type_trait<T_arg3>::take, typename
> > > sigc::type_trait<T_arg4>::take) const [with T_return =
> > > bool, T_obj = ExampleWindow, T_arg1 = GdkEventButton*,
> > > T_arg2 = char*]
> > > make: *** [eventbox] Error 1
> > > <end comp output>
> > > 
> > > Sorry for the mess and thanks for any/all suggestions.
> > > 
> > > Pete
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