[glibmm] Implement custom cast constructor for VariantBase.

[Krzesimir Nowak <krnowak src gnome org>]

commit 74be2c624ae943a9f883c2e8befe6836332269b9
Author: Krzesimir Nowak <qdlacz gmail com>
Date:   Sun Jul 22 19:51:57 2012 +0200

    Implement custom cast constructor for VariantBase.
    
    * glib/src/variant.hg:
    * glib/src/variant.ccg: Use _CUSTOM_CTOR_CAST macro and implement
    cast constructor.  This is needed, because we always want to sink
    a GVariant.

 ChangeLog            |    9 +++++++++
 glib/src/variant.ccg |   17 +++++++++++++++++
 glib/src/variant.hg  |    1 +
 3 files changed, 27 insertions(+), 0 deletions(-)
---
diff --git a/ChangeLog b/ChangeLog
index 420883b..f0ffae0 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,14 @@
 2012-07-28  Krzesimir Nowak  <qdlacz gmail com>
 
+	Implement custom cast constructor for VariantBase.
+
+	* glib/src/variant.hg:
+	* glib/src/variant.ccg: Use _CUSTOM_CTOR_CAST macro and implement
+	cast constructor.  This is needed, because we always want to sink
+	a GVariant.
+
+2012-07-28  Krzesimir Nowak  <qdlacz gmail com>
+
 	Add _CUSTOM_CTOR_CAST macro for _CLASS_OPAQUE_COPYABLE.
 
 	* tools/m4/class_opaque_copyable.m4: New macro.
diff --git a/glib/src/variant.ccg b/glib/src/variant.ccg
index c002c14..8dc5ad8 100644
--- a/glib/src/variant.ccg
+++ b/glib/src/variant.ccg
@@ -23,6 +23,23 @@
 namespace Glib
 {
 
+VariantBase::VariantBase(GVariant* castitem, bool make_a_copy /* = false */)
+{
+  if (castitem)
+  {
+    if (g_variant_is_floating(castitem))
+    {
+      g_variant_ref_sink (castitem);
+    }
+    if (make_a_copy)
+    {
+      g_variant_ref (castitem);
+    }
+  }
+
+  gobject_ = castitem;
+}
+
 void VariantBase::get_normal_form(VariantBase& result) const
 {
   GVariant* const g_value =
diff --git a/glib/src/variant.hg b/glib/src/variant.hg
index 87143bd..97f8e71 100644
--- a/glib/src/variant.hg
+++ b/glib/src/variant.hg
@@ -82,6 +82,7 @@ namespace Glib
 class VariantBase
 {
   _CLASS_OPAQUE_COPYABLE(VariantBase, GVariant, NONE, g_variant_ref_sink, g_variant_unref)
+  _CUSTOM_CTOR_CAST()
   _IGNORE(g_variant_ref, g_variant_ref_sink, g_variant_unref,
     g_variant_get, g_variant_get_va)
 public: