new functions g_prefix_error and g_propagate_prefixed_error.

2006-11-15  Ryan Lortie  <desrt@desrt.ca>

        * docs/reference/glib/glib-sections.txt:
        * glib/glib.symbols:
        * glib/gerror.h:
        * glib/gerror.c: new functions g_prefix_error and
        g_propagate_prefixed_error.


svn path=/trunk/; revision=5859

ChangeLog

@@ -1,3 +1,11 @@
+2006-11-15  Ryan Lortie  <desrt@desrt.ca>
+
+	* docs/reference/glib/glib-sections.txt:
+	* glib/glib.symbols:
+	* glib/gerror.h:
+	* glib/gerror.c: new functions g_prefix_error and
+	g_propagate_prefixed_error.
+
 2007-11-13  Cody Russell  <bratsche@gnome.org>
 
 	* docs/reference/gobject/gobject-docs.sgml:

docs/reference/glib/glib-sections.txt

@@ -386,6 +386,8 @@ g_error_matches
 g_set_error
 g_propagate_error
 g_clear_error
+g_prefix_error
+g_propagate_prefixed_error
 </SECTION>
 
 <SECTION>

glib/gerror.c

@@ -257,5 +257,82 @@ g_clear_error (GError **err)
     }
 }
 
+static void
+g_error_add_prefix (gchar       **string,
+                    const gchar  *format,
+                    va_list       ap)
+{
+  gchar *oldstring;
+  gchar *prefix;
+
+  prefix = g_strdup_vprintf (format, ap);
+  oldstring = *string;
+  *string = g_strjoin ("", prefix, oldstring, NULL);
+  g_free (oldstring);
+  g_free (prefix);
+}
+
+/**
+ * g_prefix_error:
+ * @err: a return location for a #GError, or %NULL
+ * @format: printf()-style format string
+ * ...: arguments to @format
+ *
+ * Formats a string according to @format and
+ * prefix it to an existing error message.  If
+ * @err is %NULL (ie: no error variable) then do
+ * nothing.
+ *
+ * If *@err is %NULL (ie: an error variable is
+ * present but there is no error condition) then
+ * also do nothing.  Whether or not it makes
+ * sense to take advantage of this feature is up
+ * to you.
+ **/
+void
+g_prefix_error (GError      **err,
+                const gchar  *format,
+                ...)
+{
+  if (err && *err)
+    {
+      va_list ap;
+
+      va_start (ap, format);
+      g_error_add_prefix (&(*err)->message, format, ap);
+      va_end (ap);
+    }
+}
+
+/**
+ * g_propagate_prefixed_error:
+ * @dest: error return location
+ * @src: error to move into the return location
+ * @format: printf()-style format string
+ * ...: arguments to @format
+ * 
+ * If @dest is %NULL, free @src; otherwise,
+ * moves @src into *@dest. *@dest must be %NULL.
+ * After the move, add a prefix as with 
+ * g_prefix_error().
+ **/
+void
+g_propagate_prefixed_error (GError      **dest,
+                            GError       *src,
+                            const gchar  *format,
+                            ...)
+{
+  g_propagate_error (dest, src);
+
+  if (dest && *dest)
+    {
+      va_list ap;
+
+      va_start (ap, format);
+      g_error_add_prefix (&(*dest)->message, format, ap);
+      va_end (ap);
+    }
+}
+
 #define __G_ERROR_C__
 #include "galiasdef.c"

glib/gerror.h

@@ -67,6 +67,16 @@ void     g_propagate_error     (GError       **dest,
 /* if (err && *err) { g_error_free(*err); *err = NULL; } */
 void     g_clear_error         (GError       **err);
 
+/* if (err) prefix the formatted string to the ->message */
+void     g_prefix_error               (GError       **err,
+                                       const gchar   *format,
+                                       ...) G_GNUC_PRINTF (2, 3);
+
+/* g_propagate_error then g_error_prefix on dest */
+void     g_propagate_prefixed_error   (GError       **dest,
+                                       GError        *src,
+                                       const gchar   *format,
+                                       ...) G_GNUC_PRINTF (3, 4);
 
 G_END_DECLS
 

glib/glib.symbols

@@ -320,6 +320,8 @@ g_error_new G_GNUC_PRINTF(3,4)
 g_error_new_literal
 g_propagate_error
 g_set_error G_GNUC_PRINTF(4,5)
+g_prefix_error G_GNUC_PRINTF(2,3)
+g_propagate_prefixed_error G_GNUC_PRINTF(3,4)
 #endif
 #endif