G_TYPE_<unterminated-string> (was: Re: Status of 2.0 API freeze bugs)

[Tim Janik <timj gtk org>]

On 3 Apr 2001, Owen Taylor wrote:


> 50209	gobject glib	Need a G_TYPE_ for non-nul-terminated strings 
> 
>  Patch from otaylor needs to be fixed-up / applied by timj

there are basically two issues i have with that patch.

1) the way in wich it special cases G_TYPE_BYTES in glib-genmarshal.c,
2) the argument order, which is (guint8 *bytes, guint n_bytes) in your
   patch

for (1), i need to extend glib-genmarshal.c to generically deal with in value
types that get passed as multiple args (marshalling of out value types with multiple
args are not going to be supported for 2.0).

for (2), we definitely need to change that to (guint n_bytes, guint8 *bytes),
and people have to be aware of this as these args are passed through a varargs
interface.

on why the number of elements should be passed as first arg by general
convention:

a) for varargs interfaces there's often no other way to handle this, e.g.
   old API:
   guint   gtk_signal_new  (const gchar        *name,
                            [snip]
                            guint               n_args,
                            ...);
   void   gtk_binding_entry_add_signal   (GtkBindingSet  *binding_set,
                                          [snip]
                                          guint           n_args,
                                          ...);
   new API:
   GtkListStore *gtk_list_store_new_with_types  (gint          n_columns,
                                                 ...);
b) gtk has in the past pretty consistently been doing this:
   typedef void (*GtkCallbackMarshal)  (GtkObject    *object,
                                        gpointer      data,
                                        guint         n_args,
                                        GtkArg       *args);
   guint   gtk_signal_newv             (const gchar        *name,
                                        [...]
                                        guint               n_args,
                                        GtkType            *args);
   void    gtk_container_addv          (GtkContainer      *container,
                                        GtkWidget         *widget,
                                        guint              n_args,
                                        GtkArg            *args);
   void  gtk_item_factory_delete_entries (GtkItemFactory         *ifactory,
                                          guint                   n_entries,
                                          GtkItemFactoryEntry    *entries);
c) intuitivity. i usually expect args of equal contextual relevance to be
   passed in order of significance. for a (n_elements, elements) tuple that's
   clearly n_elements, since for n_elements==0, elements can be passed as NULL
   in most APIs, we often even add checks like:
   if (n_elements)
     g_return_if_fail (elements != NULL);

(a) definitely isn't disputable, (c) i could imagine owen disagreeing on,
though i'd hope not. for (b) we even have some counter examples in gtk,
though that's mostly old API added by owen:

void gtk_drag_dest_set   (GtkWidget            *widget,
                          GtkDestDefaults       flags,
                          const GtkTargetEntry *targets,
                          gint                  n_targets,
                          GdkDragAction         actions);

and new API which should be fixed for consistency:

void     gtk_tree_view_set_rows_drag_dest     (GtkTreeView              *tree_view,
                                               const GtkTargetEntry     *targets,
                                               gint                      n_targets,
                                               GdkDragAction             actions,
                                               GtkTreeViewDroppableFunc  location_droppable_func,
                                               gpointer                  user_data);
void     gtk_tree_view_set_rows_drag_source   (GtkTreeView              *tree_view,
                                               GdkModifierType           start_button_mask,
                                               const GtkTargetEntry     *targets,
                                               gint                      n_targets,
                                               GdkDragAction             actions,
                                               GtkTreeViewDraggableFunc  row_draggable_func,
                                               gpointer                  user_data);

---
ciaoTJ