Re: patch for g_nullify_pointer() and friends

[Owen Taylor <otaylor redhat com>]

Sven Neumann <sven gimp org> writes:

> Hi,
> 
> here's a small patch that adds g_nullify_pointer() to glib and 
> g_object_[add|remove]_weak_pointer() to gobject. OK to commit?
 
 * By agreed upon convention g_nullify_pointer should
   be g_nullify_pointer_handler(). 

 * Is it really generally useful beyond add/remove_weak_ref()?

 * Your macros are missing a cast to GWeakNotify.

 * The advantages of making g_object_add/remove_weak_ref() macros
   are:
 
    - One less function call. (But this function call, in the
      event it turned out to be a performance problem, 
      could be optimized away inside gobject.c as well.)

    - Slightly decreased code size in the library

   The distandvantages are:

    - Can't use inline docs (if you go with macros, you _must_
      add an entry to docs/reference/gobject-overrides.txt
      and then fill in the docs in  docs/refererence

    - Worse error messages from the compiler.
 
    - Worse g_return_if_fail() messages.
    
    - Slightly increased code size and startup time in
      the app (the compiler needs to do a load-time lookup of 
      g_nullify_pointer)

    It's not a big deal either way - I'd certainly go
    with the functions myself. (I _did_ go with the functions
    myself in the earlier patch I submitetd...)

Regards,
                                        Owen

> Index: glib/gutils.c
> ===================================================================
> RCS file: /cvs/gnome/glib/glib/gutils.c,v
> retrieving revision 1.97
> diff -u -r1.97 gutils.c
> --- glib/gutils.c	2001/06/30 16:54:32	1.97
> +++ glib/gutils.c	2001/08/03 15:50:03
> @@ -1046,6 +1046,18 @@
>  }
>  
>  /**
> + * g_nullify_pointer:
> + * @nullify_location: the memory address of the pointer.
> + * 
> + * Set the pointer at the specified location to %NULL.
> + **/
> +void
> +g_nullify_pointer (gpointer *nullify_location)
> +{
> +  *nullify_location = NULL;
> +}
> +
> +/**
>   * g_get_codeset:
>   * 
>   * Get the codeset for the current locale.
> Index: glib/gutils.h
> ===================================================================
> RCS file: /cvs/gnome/glib/glib/gutils.h,v
> retrieving revision 1.10
> diff -u -r1.10 gutils.h
> --- glib/gutils.h	2001/07/10 22:37:07	1.10
> +++ glib/gutils.h	2001/08/03 15:50:03
> @@ -165,6 +165,10 @@
>  gchar*                g_path_get_basename  (const gchar *file_name);
>  gchar*                g_path_get_dirname   (const gchar *file_name);
>  
> +
> +/* Set the pointer at the specified location to NULL */
> +void                  g_nullify_pointer    (gpointer    *nullify_location);
> +
>  /* Get the codeset for the current locale */
>  /* gchar * g_get_codeset    (void); */
>  
> Index: gobject/gobject.h
> ===================================================================
> RCS file: /cvs/gnome/glib/gobject/gobject.h,v
> retrieving revision 1.16
> diff -u -r1.16 gobject.h
> --- gobject/gobject.h	2001/07/02 05:02:13	1.16
> +++ gobject/gobject.h	2001/08/03 15:50:03
> @@ -216,6 +216,11 @@
>  #define G_OBJECT_WARN_INVALID_PROPERTY_ID(object, property_id, pspec) \
>      G_OBJECT_WARN_INVALID_PSPEC ((object), "property id", (property_id), (pspec))
>  
> +#define g_object_add_weak_pointer(object,weak_pointer) \
> +    g_object_weak_ref ((object), g_nullify_pointer, (weak_pointer))
> +#define g_object_remove_weak_pointer(object,weak_pointer) \
> +    g_object_weak_unref ((object), g_nullify_pointer, (weak_pointer))
> +
>  G_END_DECLS
>  
>  #endif /* __G_OBJECT_H__ */
> 
> 
> 
> 
> 
> 
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