Re: Function completion for GVariant maybe types?

[Markus Elfring <Markus Elfring web de>]

> > Is it possible to determine the child data type without retrieving
> > the complete value?
>
> See above.

How do you think about the following update suggestion?


diff --git a/glib/gvariant.c b/glib/gvariant.c
index c3d1947..9c107dd 100644
--- a/glib/gvariant.c
+++ b/glib/gvariant.c
@@ -682,6 +682,27 @@ g_variant_new_maybe (const GVariantType *child_type,
   return value;
 }

+GVariant *
+g_variant_new_nothing_from_type (GVariant const * value)
+{
+  if (value == NULL)
+ 	return g_variant_new ("ms", NULL);
+  else
+    {
+	  GVariantType* type = g_variant_get_type (value);
+
+      if (g_variant_type_is_maybe (type))
+        {
+		  GVariant* contained = g_variant_get_child_value (value, 0);
+		  type = g_variant_get_type (contained);
+		  g_variant_unref(contained);
+		  return g_variant_new_maybe (type, NULL);
+        }
+      else
+ 		  return g_variant_new_maybe (type, value);
+    }
+}
+
 /**
  * g_variant_get_maybe:
  * @value: a maybe-typed value
diff --git a/glib/gvariant.h b/glib/gvariant.h
index 9abcc0b..50877f2 100644
--- a/glib/gvariant.h
+++ b/glib/gvariant.h
@@ -128,6 +128,7 @@ gchar ** 
g_variant_dup_bytestring_array          (GVarian

 GVariant *                      g_variant_new_maybe                     (const 
GVariantType   *child_type,

GVariant             *child);
+GVariant *                      g_variant_new_nothing_from_type 
(GVariant const * value);
 GVariant *                      g_variant_new_array                     (const 
GVariantType   *child_type,

GVariant * const     *children,
                                                                          gsize 
                n_children);



> The usual answer to "should we optimise $THING?" applies:
> if you don't have profiling data that indicates that $THING is a bottleneck,
> then no, optimising $THING isn't useful.

Would it be more efficient to query only a data type instead of copying a 
potential big data structure?

Regards,
Markus