[C++] sigc::mem_fun / GTKmm question (pointers and classes)

[Temppu]

Hi,

And thanks in advance if somebody is able to help me.

I started programming again, having missed seven to eight years. As my history is in TPascal->Java->VB, I decided to learn some C++. While learning, I tried to get rid of bad habits, so I went in classes and such, trying to build easily manageable files.

I am using Ubuntu and wanted to do GUI, so I went for GTKmm. My whole project is now about 6 different header files, from file operations to drawing in Cairo. I am now getting into situations where I have to put information both ways from classes to others. Biggest problem (where I am stuck now) is the signals from buttons to do something in another class:


m_buttonrefresh.signal_clicked().connect( sigc::mem_fun(*this, &Window::on_clicked) );

If Window is not the class in who's constructor I this is in, it does not work. For better idea what I am talking about, I made this example:

apu.h

#ifndef INDEKSI
#define INDEKSI

#include <gtkmm.h>

class Indeksi
{
public:
Indeksi();
virtual ~Indeksi();

void on_button_clicked();

};

#endif //INDEKSI

apu.cc

#include "apu.h"
#include <iostream>

Indeksi::Indeksi()
{
}

Indeksi::~Indeksi()
{
}


void Indeksi::on_button_clicked()
{
std::cout << "teksti";
}

helloworld.h

#ifndef GTKMM_EXAMPLE_HELLOWORLD_H
#define GTKMM_EXAMPLE_HELLOWORLD_H
#include "apu.h"
#include <gtkmm/button.h>
#include <gtkmm/window.h>



class HelloWorld : public Gtk::Window
{

public:
HelloWorld();
virtual ~HelloWorld();

protected:

void on_button_clicked();
Gtk::Button m_button;
};

#endif // GTKMM_EXAMPLE_HELLOWORLD_H

helloworld.cc


#include "helloworld.h"
#include <iostream>



HelloWorld::HelloWorld()
: m_button("Hello World")
{

set_border_width(10);

m_button.signal_clicked().connect(sigc::mem_fun(*t his, &Indeksi::on_button_clicked));
add(m_button);
m_button.show();
}

HelloWorld::~HelloWorld()
{
}

void HelloWorld::on_button_clicked()
{
std::cout << "Hello World" << std::endl;
}



main.cc

#include "helloworld.h"
#include <gtkmm/main.h>

int main (int argc, char *argv[])
{
Gtk::Main kit(argc, argv);
HelloWorld helloworld;
Gtk::Main::run(helloworld);

return 0;
}

Output:


In file included from /usr/include/sigc++-2.0/sigc++/adaptors/adaptor_trait.h:9:0,
from /usr/include/sigc++-2.0/sigc++/functors/slot.h:7,
from /usr/include/sigc++-2.0/sigc++/signal_base.h:31,
from /usr/include/sigc++-2.0/sigc++/signal.h:8,
from /usr/include/sigc++-2.0/sigc++/sigc++.h:23,
from /usr/include/glibmm-2.4/glibmm/signalproxy.h:13,
from /usr/include/glibmm-2.4/glibmm/objectbase.h:23,
from /usr/include/glibmm-2.4/glibmm/wrap.h:26,
from /usr/include/glibmm-2.4/glibmm/containerhandle_shared.h:25,
from /usr/include/glibmm-2.4/glibmm/arrayhandle.h:23,
from /usr/include/glibmm-2.4/glibmm.h:83,
from /usr/include/gtkmm-2.4/gtkmm.h:87,
from apu.h:4,
from helloworld.h:3,
from helloworld.cc:2:
/usr/include/sigc++-2.0/sigc++/functors/mem_fun.h: In function ‘sigc::bound_mem_functor0<T_return, T_obj> sigc::mem_fun(T_obj&, T_return (T_obj2::*)()) [with T_return = void, T_obj = HelloWorld, T_obj2 = Indeksi]’:
helloworld.cc:13:85: instantiated from here
/usr/include/sigc++-2.0/sigc++/functors/mem_fun.h:5453:61: error: no matching function for call to ‘sigc::bound_mem_functor0<void, HelloWorld>::bound_mem_functor0(HelloWorld&, void (Indeksi::*&)())’
/usr/include/sigc++-2.0/sigc++/functors/mem_fun.h:1778:3: note: candidates are: sigc::bound_mem_functor0<T_return, T_obj>::bound_mem_functor0(T_obj&, sigc::bound_mem_functor0<T_return, T_obj>::function_type) [with T_return = void, T_obj = HelloWorld, sigc::bound_mem_functor0<T_return, T_obj>::function_type = void (HelloWorld::*)()]
/usr/include/sigc++-2.0/sigc++/functors/mem_fun.h:1769:3: note: sigc::bound_mem_functor0<T_return, T_obj>::bound_mem_functor0(T_obj*, sigc::bound_mem_functor0<T_return, T_obj>::function_type) [with T_return = void, T_obj = HelloWorld, sigc::bound_mem_functor0<T_return, T_obj>::function_type = void (HelloWorld::*)()]
/usr/include/sigc++-2.0/sigc++/functors/mem_fun.h:1760:1: note: sigc::bound_mem_functor0<void, HelloWorld>::bound_mem_functor0(const sigc::bound_mem_functor0<void, HelloWorld>&)


If I replace &Indeksi::on_button_clicked with &HelloWorld::on_button_clicked, it works nicely.

I only know that this probably something to do with pointers and sigc::mem_fun, but have no clue how to fix it. Help is truly appreciated!

[Temppu]

Solved. I had to pass the pointer to Indeksi. I was passing it to Helloworld, by using "this".