GObject Unterklasse in C kann keine Unterklasseninstanz erstellen

Question

Ich wollte die GObject API versuchen. Die Idee ist, eine Vehicule-Klasse zu erstellen, die eine DERIVABLE Art ist und eine Unterklasse von Vehicule namens Car zu erstellen, die ein FINAL Typ ist. Mein Problem ist, dass, wenn ich in einem kleinen Programm versuche, eine Klasse Car zu erstellen, mein Programm blockiert und nicht bei der Erstellung der Instanz zurückkehrt.

Hier ist der Mindestcode, um mein Problem zu reproduzieren. Ich benutze das Konventionstuto-Vehicule/Tuto-Auto.

tuto-vehicule.h

#ifndef __TUTO_VEHICULE_H__ 
#define __TUTO_VEHICULE_H__ 
#include <glib-object.h> 

G_BEGIN_DECLS 

typedef struct _TutoVehiculePrivate { 
    GObject parent_instance; 
    GString *name; 
    guint nb_wheels; 
} TutoVehiculePrivate; 

typedef struct _TutoVehiculeClass { 
    GObjectClass parent_class; 
} TutoVehiculeClass; 

#define TUTO_TYPE_VEHICULE tuto_vehicule_get_type() 
G_DECLARE_DERIVABLE_TYPE(TutoVehicule, tuto_vehicule, TUTO, VEHICULE, GObject); 


TutoVehicule *tuto_vehicule_new (void); 

void tuto_vehicule_set_name(TutoVehicule *self, gchar *name); 
void tuto_vehicule_set_nb_wheels(TutoVehicule *self, gint nb_wheels); 
void tuto_vehicule_print_name(TutoVehicule *self); 
void tuto_vehicule_print_nb_wheels(TutoVehicule *self); 

G_END_DECLS 

#endif 

tuto-vehicule.c

#include "tuto-vehicule.h" 
#include <stdio.h> 

G_DEFINE_TYPE_WITH_PRIVATE(TutoVehicule, tuto_vehicule, G_TYPE_OBJECT); 

static void 
tuto_vehicule_dispose(GObject *object) 
{ 
    TutoVehiculePrivate *priv = tuto_vehicule_get_instance_private(TUTO_VEHICULE(object)); 
    printf("tuto_vehicule_dispose\n"); 
    g_string_free(priv->name, TRUE); 
    G_OBJECT_CLASS(tuto_vehicule_parent_class)->dispose(object); 
} 

static void 
tuto_vehicule_class_init(TutoVehiculeClass *klass) 
{ 
    GObjectClass *g_object_class = G_OBJECT_CLASS(klass); 
    /* instance destructor*/ 
    g_object_class->dispose = tuto_vehicule_dispose; 
    printf("tuto_vehicule_class_init for TutoVehiculeClass created by G_DECLARE_DERIVABLE_TYPE\n"); 
} 

static void 
tuto_vehicule_init(TutoVehicule *self) 
{ 
    TutoVehiculePrivate *priv = tuto_vehicule_get_instance_private(self); 
    priv->name = g_string_new(NULL); 
    priv->nb_wheels = 0; 
    printf("tuto_vehicule_init\n"); 
} 

TutoVehicule * 
tuto_vehicule_new(void) 
{ 
    TutoVehicule *vehicule_instance = g_object_new(TUTO_TYPE_VEHICULE, NULL); 
    return vehicule_instance; 
} 

void tuto_vehicule_set_name(TutoVehicule *self, gchar *name) 
{ 
    TutoVehiculePrivate *priv = tuto_vehicule_get_instance_private(self); 
    g_string_assign(priv->name, name); 
} 

void tuto_vehicule_set_nb_wheels(TutoVehicule *self, gint nb_wheels) 
{ 
    TutoVehiculePrivate *priv = tuto_vehicule_get_instance_private(self); 
    priv->nb_wheels = nb_wheels; 
} 

void tuto_vehicule_print_name(TutoVehicule *self) 
{ 
    TutoVehiculePrivate *priv = tuto_vehicule_get_instance_private(self); 
    printf("Vehicule name: %s\n", priv->name->str); 
} 

void tuto_vehicule_print_nb_wheels(TutoVehicule *self) 
{ 
    TutoVehiculePrivate *priv = tuto_vehicule_get_instance_private(self); 
    printf("Vehicule number of wheels: %d\n", priv->nb_wheels); 
} 

tuto-car.h

#ifndef __TUTO_CAR_H 
#define __TUTO_CAR_H 
#include "tuto-vehicule.h" 
#include <glib-object.h> 

G_BEGIN_DECLS 

#define TUTO_TYPE_CAR tuto_car_get_type() 
G_DECLARE_FINAL_TYPE(TutoCar, tuto_car, TUTO, CAR, TutoVehicule); 

typedef struct _TutoCar { 
    TutoVehicule parent_instance; 
} TutoCar; 

TutoCar *tuto_car_new(void); 
void tuto_car_print_name(TutoCar *self); 
void tuto_car_print_nb_wheels(TutoCar *self); 
G_END_DECLS 
#endif 

Tuto-car.c

#include "tuto-car.h" 
#include <stdio.h> 

G_DEFINE_TYPE(TutoCar, tuto_car, TUTO_TYPE_CAR); 

static void 
tuto_car_class_init(TutoCarClass *klass) 
{ 
    printf("tuto_car_class_init\n"); 
} 

static void 
tuto_car_init(TutoCar *self) 
{ 
    printf("tuto_car_init\n"); 
} 

TutoCar * 
tuto_car_new(void) 
{ 
    TutoCar *car = g_object_new(TUTO_TYPE_CAR, NULL); 
    tuto_vehicule_set_name(TUTO_VEHICULE(car), "car"); 
    tuto_vehicule_set_nb_wheels(TUTO_VEHICULE(car), 4); 
    return car; 
} 

void 
tuto_car_print_name(TutoCar *self) 
{ 
    tuto_vehicule_print_name(TUTO_VEHICULE(self)); 
} 

void 
tuto_car_print_nb_wheels(TutoCar *self) 
{ 
    tuto_vehicule_print_nb_wheels(TUTO_VEHICULE(self)); 
} 

ich diese zwei Klassen in einer einfachen Haupt Datei:

#include <stdio.h> 
#include "tuto-vehicule.h" 
#include "tuto-car.h" 

int main(int argc, char **argv) 
{ 
    printf("Create a TutoVehicule instance\n"); 

    TutoVehicule *moto = tuto_vehicule_new(); 
    printf("Puts its name to moto\n"); 
    tuto_vehicule_set_name(moto, "moto"); 
    printf("Puts its number of wheels to 2\n"); 
    tuto_vehicule_set_nb_wheels(moto, 2); 

    printf("Create a TutoCar instance\n"); 
    TutoCar *car = tuto_car_new(); 

    printf("Use methods instance\n"); 

    tuto_vehicule_print_name(moto); 
    tuto_vehicule_print_nb_wheels(moto); 

    tuto_vehicule_print_name(TUTO_VEHICULE(car)); 
    tuto_vehicule_print_nb_wheels(TUTO_VEHICULE(car)); 

    tuto_car_print_name(car); 
    tuto_car_print_nb_wheels(car); 

    printf("Destroy the instances created previously\n"); 
    g_object_unref(car); 
    g_object_unref(moto); 

    return 0; 
} 

Die Zusammenstellung arbeitet mit:

gcc -Wall -o main_vehicule `pkg-config --libs --cflags gobject-2.0` main_vehicule.c tuto-car.c tuto-vehicule.c 

Aber wenn ich das Programm ausführen Wie ich unten gesagt habe, habe ich diese Ausgabe und den Programmblock ohne zurückzusenden oder Fehlermeldungen auszugeben:

Create a TutoVehicule instance 
tuto_vehicule_class_init for TutoVehiculeClass created by G_DECLARE_DERIVABLE_TYPE 
tuto_vehicule_init 
Puts its name to moto 
Puts its number of wheels to 2 
Create a TutoCar instance 

Ich weiß, dass mein Programm Block an dieser Aussage:

TutoCar *car = g_object_new(TUTO_TYPE_CAR, NULL); 

Was habe ich verpasst? Die offiziellen Dokumente sind nicht wirklich klar.

bearbeiten

Hier ist eine GDB-Sitzung:

(gdb) break tuto-car.c:tuto_car_new 
Breakpoint 1 at 0x400dcb: file tuto-car.c, line 21. 
(gdb) run 
Starting program: /home/cedlemo/Projets/C/GObject/derivable_type/main_vehicule 
[Thread debugging using libthread_db enabled] 
Using host libthread_db library "/usr/lib/libthread_db.so.1". 
Create a TutoVehicule instance 
tuto_vehicule_class_init for TutoVehiculeClass created by G_DECLARE_DERIVABLE_TYPE 
tuto_vehicule_init 
Puts its name to moto 
Puts its number of wheels to 2 
Create a TutoCar instance 

Breakpoint 1, tuto_car_new() at tuto-car.c:21 
21  TutoCar *car = g_object_new(TUTO_TYPE_CAR, NULL); 
(gdb) backtrace 
#0 tuto_car_new() at tuto-car.c:21 
#1 0x0000000000400c02 in main (argc=1, argv=0x7fffffffded8) at main_vehicule.c:16 
(gdb) next 

Der Programmblock in gdb auch so hatte ich ctrl + c und prüfen Sie den Stapel schlagen:

(gdb) backtrace 
#0 0x00007ffff75ba269 in syscall() from /usr/lib/libc.so.6 
#1 0x00007ffff790618f in g_cond_wait() from /usr/lib/libglib-2.0.so.0 
#2 0x00007ffff78e8437 in g_once_init_enter() from /usr/lib/libglib-2.0.so.0 
#3 0x0000000000400d1e in tuto_car_get_type() at tuto-car.c:4 
#4 0x0000000000400d44 in tuto_car_get_type() at tuto-car.c:4 
#5 0x0000000000400dd0 in tuto_car_new() at tuto-car.c:21 
#6 0x0000000000400c02 in main (argc=1, argv=0x7fffffffded8) at main_vehicule.c:16 

Answer 1

Hier ist die Antwort:

in der Datei Tuto-Auto.c, I a die Linie:

G_DEFINE_TYPE(TutoCar, tuto_car, TUTO_TYPE_CAR); 

für die beiden Makros:

• G_DEFINE_TYPE
• G_DEFINE_TYPE_WITH_PRIVATE

Der letzte Parameter ist der GType des Elternteils. In meinem Code habe ich den GType der Klasse selbst benutzt. Ich hätte TUTO_TYPE_VEHICULE

G_DEFINE_TYPE(TutoCar, tuto_car, TUTO_TYPE_VEHICULE); 

Damit der vorherige Code wird voll funktionsfähigen verwendet.