如何在新结构中使指针兼容？

Question

I am trying 'inherit' a GtkWidget. I could inherit any other widget like GtkWindow etc and implement its methods in its own file. I am then going to load the new widget with a function which returns the widget like so return g_object_new(... .

The code works fine but I get incompatible pointer type warning in the struct init function.

class.h

#ifndef CLASS_H_INCLUDED
#define CLASS_H_INCLUDED

#include <gtk/gtk.h>
#define CLASS_NAME_TYPE (class_name_get_type())
G_DECLARE_FINAL_TYPE(ClassName, class_name, CLASS, NAME, GtkWidget)

ClassName *class_name_new();

#endif // CLASS_H_INCLUDED

class.c

#include "class.h"

struct _ClassName
{
  GtkWidget parent;
};

G_DEFINE_TYPE(ClassName, class_name, GTK_TYPE_WIDGET);

static void class_name_init(ClassName *self)
{
    gtk_widget_set_name(self, "Widget");
}

static void class_name_class_init(ClassNameClass *klass)
{

}

ClassName *class_name_new()
{
    return g_object_new(CLASS_NAME_TYPE, /* "foo", bar ,*/ NULL);
}

In the function static void class_name_init(ClassName *self) , I want to use the pointer self like so

gtk_widget_set_name(self, "Widget");

This is where I have compatible pointer type. gtk_widget_set_name() is expecting a type GtkWidget as an input but the init function has the type ClassName .

Gtk knows ClassName is the same type as GtkWidget hence the code works but is there anyway to fix the code so that the compiler doesn't think its a mistake

Answer 1

通常，您应该使用强制转换操作符来避免编译器警告，假设self是一个指针：

gtk_widget_set_name((GtkWidget*)self, "Widget");

Answer 2

Defining the object also works like so GTK_WIDGET(obj)

Instead of

gtk_widget_set_name(self, "Widget"); 

do

gtk_widget_set_name(GTK_WIDGET(self), "Widget");`

You can always define the object if self is a window GTK_WINDOW(self)