RE: (gtk_pixmap_new): assertion `val != NULL' failed

["Ronald Bultje" <rbultje ronald bitfreak net>]

Hi again,

mr. stupid was playing in my head again.

>> #include "image.xpm"
>> void create_pixmap(GtkWidget *w) {
>>   GdkPixmap *pixmap;
>>   GdkBitmap *mask;
>>   pixmap = gdk_pixmap_colormap_create_from_xpm_d (NULL,
>>      gtk_widget_get_default_colormap(),
>>      &mask, NULL, (gchar **)image_xpm);
>>   w = gtk_pixmap_new (pixmap, mask);
>> }
>> void test() {
>>   GtkWidget *w = NULL;
>>   create_pixmap(w);
>>   if (w == NULL) g_print("I am stupid\n");
>>   else g_print("I am not that stupid\n");
>> }
>> ---
>> 
>> Should return "I am not that stupid", right? (I don't have a xwindows
>> computer on my hands here so I can't test it - grom).
>
>unless create_pixmap(w) is C++ with an referens argument this program 
>*will* output "I am stupid\n". In C, ther is *no* way the 
>create_pixmap
>funktion can change its argument. It can change the memory the pointer
>points to (but then it have to be pointing to valid memory, not NULL),
>but it can *not* change the pointer itself. So, i C, w is garanteed 
>to still point to NULL! You actuly have to send a pointer to a pointer 
>for the funktion to be able to change the pointer.

Double oops. I forgot that. Let's try this one then:

#include "image.xpm"
void create_pixmap(GtkWidget **w) {
  GdkPixmap *pixmap;
  GdkBitmap *mask;
  pixmap = gdk_pixmap_colormap_create_from_xpm_d (NULL,
     gtk_widget_get_default_colormap(),
     &mask, NULL, (gchar **)image_xpm);
  *w = gtk_pixmap_new (pixmap, mask);
}
void test() {
  GtkWidget *w = NULL;
  create_pixmap(&w);
  if (w == NULL) g_print("I am stupid\n");
  else g_print("I am not that stupid\n");
}

This better? :-)
Stupid me...

Regards,

Ronald