Re: sigc::ptr_fun() compiler error

[Ron Lockwood-Childs <rchilds vctlabs com>]

Bob Caryl wrote:
> Ron Lockwood-Childs wrote:
>
> > Hello,
> >
> > I get an error when trying to compile the following code:
> >
> > test.h
> > ------
> > #include <libglademm/xml.h>
> > #include <gtkmm>
> > #include <iostream>
> >
> > class Test
> > {
> >   Glib::RefPtr<Gnome::Glade::Xml> refXml;
> >   Gtk::Window *pMWindow;
> >   void on_quit_activate() { if (pMWindow) pMWindow->hide(); }
> > public:
> >   Test( int argc, char **argv, char *glade_path );
> > };
> >
> > test.cc
> > -------
> > #include <libglademm/xml.h>
> > #include <gtkmm>
> > #include <iostream>
> > #include "test.h"
> >
> > Test::Test( int argc, char **argv, char *glade_path )
> > {
> >   try
> >   {
> >     refXml = Gnome::Glade::Xml::create( glade_path );
> >   }
> >   catch(const Gnome::Glade::XmlError& ex)
> >   {
> >     std::cerr << ex.what() << std::endl;
> >     exit( 1 );
> >   }
> >
> >   refXml->get_widget("mainwindow", pMWindow);
> >   if (pMWindow)
> >   {
> >       Gtk::MenuItem* pMenuItem = 0;
> >       refXml->get_widget("menu_file_quit", pMenuItem);
> >       if(pMenuItem)
> >       {
> >         pMenuItem->signal_activate().connect(
> >           sigc::ptr_fun( &Test::on_quit_activate ) );
> >       }
> >   }
> > }
> >
> > int main( argc, argv )
> > {
> >   Test testDialog = new Test( argc, argv, "test.glade" );
> >   return 0;
> > }
> >
> > ---------
> > (if I've made copy-paste errors, FWIW the actual code doesn't get 
> > syntax errors..)
> >
> > Finally, when I attempt compilation, this is what I get:
> >
> > $ g++ test.cc -o test `pkg-config gtkmm-2.4 --cflags --libs` 
> > -lglademm-2.4
> > test.cc: In constructor `Test::Test(int, char**, char*)':
> > test.cc: error: no matching function for call to `ptr_fun(void 
> > (Test::*)())'
> >
> > This was taken from the tutorial, except that now I'm attempting to 
> > put the UI code into its own class.  It gives me no hint on why it 
> > can't find the function.  If I do anything to the function pointer, 
> > such as:
> > sigc::ptr_fun(&(Test::on_quit_activate))
> > or
> > sigc::ptr_fun(&(this->on_quit_activate))
> > I get the same error, with another complaint regarding ANSI C++ and 
> > pointers to non-static member functions.  This signal handler must be 
> > a member function, since it accesses private data.
> >
> > Anyone seen this or similar errors & can offer help?  I'd appreciate it.
> >
> > --
> > Ron Lockwood-Childs
> > _______________________________________________
> > gtkmm-list mailing list
> > gtkmm-list gnome org
> > http://mail.gnome.org/mailman/listinfo/gtkmm-list
> Your compiler is unhappy because you are trying to pass a class member 
> function to sigc::ptr_fun when it is expecting a NON class member 
> function.  Try using sigc::mem_fun with the following syntax to pass 
> your member function:
>
> pMenuItem->signal_activate().connect( sigc::mem_fun( *this, 
> &Test::on_quit_activate ) );
>
> I hope this helps you out.
>
> Bob Caryl

Thanks for the replies on this one.  Recommendation to the doc team, 
please make this difference between mem_fun() and ptr_fun() a little 
clearer in the tutorial page:
http://www.gtkmm.org/docs/gtkmm-2.4/docs/tutorial/html/apb.html

Working in the embedded field as long as I have, my mind automatically 
expands "mem" to "memory"..

--
Ron Lockwood-Childs