instance_ext.rs: Use ObjectExt::connect() instead of the unsafe bindings

Close #42

src/gen/instance_ext.rs

@@ -88,7 +88,6 @@ pub fn slot_trait_impls<'ast>(names: &Names, slots: &[Slot<'ast>]) -> Vec<TokenS
 
             Slot::Signal(ref signal) => {
                 let connect_signalname = signals::connect_signalname(signal);
-                let signalname_trampoline = signals::signal_trampoline_name(signal);
                 let sig = &signal.sig;
                 let signalname_str = signals::canonicalize_signal_name(&sig.name.to_string())
                     .expect("rust identifiers should always be canonicalizable");
@@ -99,15 +98,10 @@ pub fn slot_trait_impls<'ast>(names: &Names, slots: &[Slot<'ast>]) -> Vec<TokenS
                     fn #connect_signalname<F: Fn(&Self, #input_types) #output + 'static>(&self, f: F) ->
                         glib::SignalHandlerId
                     {
-                        unsafe {
-                            let f: Box<Box<Fn(&Self, #input_types) #output + 'static>> =
-                                Box::new(Box::new(f));
-
-                            glib::signal::connect(self.to_glib_none().0,
-                                                  #signalname_str,
-                                                  mem::transmute(#signalname_trampoline::<Self> as usize),
-                                                  Box::into_raw(f) as *mut _)
-                        }
+                        glib::ObjectExt::connect(self.to_glib_none().0,
+                                              #signalname_str,
+                                              false,
+                                              f).unwrap()
                     }
                 })
             }