Re: What's problem with my source code?

[Tristan Van Berkom <vantr touchtunes com>]

try putting:
        parent_class = g_type_class_peek_parent(g_class)
in your class_init of person. (This will initialize
the GObject parent and give you the correct address if
you wish to use polymorphism).


also:
        Peter and Tom are people and GObject's
(If initialized properly). Peter and Tom are
not TestIFaces.


        -Tristan

Ëιúΰ wrote:
> Hi, everyone!
>
> I write a program to test GTypeInterface .
> The code here:
> //----------------------------------------------
> //test.c
> #include <glib.h>
> #include <glib-object.h>
>
> #define TYPE_TEST_IFACE (test_iface_get_type())
> #define TEST_IFACE(obj) (G_TYPE_CHECK_INSTANCE_CAST((obj),TYPE_TEST_IFACE,TestIFace))
> #define TEST_IFACE_GET_CLASS(obj)       (G_TYPE_INSTANCE_GET_CLASS((obj),TYPE_TEST_IFACE,TestIFaceClass))
>
> typedef struct _TestIFace TestIFace;
> typedef struct _TestIFaceClass TestIFaceClass;
>
> struct _TestIFaceClass
> {
>         GTypeInterface base;
>         //
>         void    (*output) (gchar* string);
>         void    (*hello) (void);
> };
>
> GType   test_iface_get_type(void);
> static gint count=0;
> static void test_iface_init(TestIFaceClass* klass);
> static void test_iface_finalize(TestIFaceClass* klass);
>
> GType   test_iface_get_type(void)
> {
>         static GType test_iface_type = 0;
>         if(!test_iface_type)
>         {
>                 static const GTypeInfo test_iface_info = {
>                         sizeof(TestIFaceClass),
>                         (GBaseInitFunc)test_iface_init,
>                         (GBaseFinalizeFunc)test_iface_finalize,
>                         NULL,NULL,NULL,0,0,NULL
>                 };
>                 test_iface_type = g_type_register_static(G_TYPE_INTERFACE,"TestIFace",&test_iface_info,0);
>                 g_type_interface_add_prerequisite(test_iface_type,G_TYPE_OBJECT);
>         }
>         return test_iface_type;
> }
>
> static void test_iface_init(TestIFaceClass* klass)
> {
>         count++;
> }
>
> static void test_iface_finalize(TestIFaceClass* klass)
> {
>         count--;
> }
>
> // the person object
>
> #define TYPE_PERSON     (person_get_type())
> #define PERSON(obj)     (G_TYPE_CHECK_INSTANCE_CAST((obj),TYPE_PERSON,Person))
> #define PERSON_GET_CLASS(obj)   (G_TYPE_INSTANCE_GET_CLASS((obj),TYPE_PERSON,PersonClass))
>
> typedef struct _Person Person;
> typedef struct _PersonClass PersonClass;
>
> struct _Person {
>         GObject parent_instance;
>         //
>         gint age;
>         gchar* name;
> };
>
> struct _PersonClass {
>         GObjectClass parent_class;
> };
>
> GType   person_get_type(void);
> GObject* person_new(void);
> void    person_set_name(GObject* person, gchar* name);
> gchar*  person_get_name(GObject* person);
> void    person_set_age(GObject* person, gint age);
> gint    person_get_age(GObject* person);
> GObject* person_new_with_name_and_age(gchar* name, gint age);
> void    person_output(GObject* person);
> void    iface_print(TestIFace* iface, gchar* string);
> void    iface_hello(TestIFace* iface);
>
> //
>
> static void output(gchar* string);
> static void hello(void);
>
> static void iface_init(gpointer iface, gpointer data);
>
> static void person_init(Person *person);
> static void person_class_init(PersonClass *klass);
>
> GType   person_get_type(void)
> {
>         static GType person_type = 0 ;
>         if(!person_type)
>         {
>                 static const GTypeInfo person_info = {
>                         sizeof(PersonClass),
>                         NULL,
>                         NULL,
>                         (GClassInitFunc)person_class_init,
>                         NULL,
>                         NULL,
>                         sizeof(Person),
>                         0,
>                         (GInstanceInitFunc)person_init
>                         };
>                 static const GInterfaceInfo iface_info = {
>                         (GInterfaceInitFunc)iface_init,
>                         NULL,NULL};
>                 person_type = g_type_register_static(G_TYPE_OBJECT,"Person",&person_info,0);
>                 g_type_add_interface_static(person_type,TYPE_TEST_IFACE,&iface_info);
>         }
>         return person_type;
> }
>
> static void person_init(Person *person)
> {
>         person->age = 0;
>         person->name = NULL;
> }
>
> static void person_class_init(PersonClass *klass)
> {
>         //without code here
> }
>
> GObject* person_new(void)
> {
>         return g_object_new(TYPE_PERSON,NULL);
> }
>
> void    person_set_name(GObject* person, gchar* name)
> {
>         PERSON(person)->name = name;
> }
>
> gchar*  person_get_name(GObject* person)
> {
>         return PERSON(person)->name;
> }
>
> void    person_set_age(GObject* person, gint age)
> {
>         PERSON(person)->age = age;
> }
>
> gint    person_get_age(GObject* person)
> {
>         return PERSON(person)->age;
> }
>
> GObject* person_new_with_name_and_age(gchar* name, gint age)
> {
>         GObject* person;
>         person = person_new();
>         person_set_name(person, name);
>         person_set_age(person, age);
>         return person;
> }
>
> void    person_output(GObject* person)
> {
>         g_print("This person name is %s, age is %d.\n",
>                 person_get_name(person), person_get_age(person));
> }
>
> static void iface_init(gpointer iface, gpointer data)
> {
>         TestIFaceClass *klass = iface;
>         g_assert(G_TYPE_FROM_INTERFACE(iface) == TYPE_TEST_IFACE);
>         klass->output = output;
>         klass->hello = hello;
> }
>
> void    output(gchar* string)
> {
>         g_print("The string is : %s \n", string);
> }
>
> void    iface_print(TestIFace* iface, gchar* string)
> {
>         TestIFaceClass* klass;
>         klass = TEST_IFACE_GET_CLASS(iface);
>         klass->output(string);
>         //TEST_IFACE_GET_CLASS(iface)->output(string);
> }
>
> void    iface_hello(TestIFace* iface)
> {
>         TEST_IFACE_GET_CLASS(iface)->hello();
> }
>
> void    hello(void)
> {
>         g_print("Hello everyone!\n");
> }
>
> //      the main function
>
> int     main(int argc, char *argv[])
> {
>         GObject *tom, *peter;
>         //Person* person;
>
>         g_type_init();
>
>         tom = person_new();
>         person_set_name(tom, "Tom London");
>         person_set_age(tom, 18);
>         //
>         person_output(tom);
>
>         peter = person_new_with_name_and_age("Peter White",20);
>         //
>         person_output(peter);
>
>         //iface_print(TEST_IFACE(peter),"this is peter");
>         iface_print(TEST_IFACE(peter),"this is peter");
>         iface_hello(TEST_IFACE(tom));
>
>         //person = g_object_new(TYPE_PERSON,NULL);
>         //person_output(G_OBJECT(person));
>         //iface_hello(TEST_IFACE(person));
> }
>
> //------------------------------------------------------
>
> the Makefile here :
>
> CC = gcc
>
> all:
>         $(CC) -o t test.c `pkg-config --libs --cflags glib-2.0 gobject-2.0`
>
> //------------------------------------------------------
>
> When I run ./t it's output message:
>
> This person name is Tom London, age is 18.
> This person name is Peter White, age is 20.
>
> (process:647): GLib-GObject-WARNING **: cannot create new instance of invalid (non-instantiatable) type 
> `(null)'
> Segmentation fault
>
> //------------------------------------------------------
>
> What's problem with my program?
> thanks everyone!
>
> gwsong_jl sohu com
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