eoserial: traits for knowing whether a class is derived from another one at compile time. Thanks Herb Sutter

eo/src/serial/Traits.h

@@ -0,0 +1,58 @@
+/*
+(c) Benjamin Bouvier, 2013
+
+    This library is free software; you can redistribute it and/or
+    modify it under the terms of the GNU Lesser General Public
+    License as published by the Free Software Foundation;
+    version 2 of the License.
+
+    This library is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+    Lesser General Public License for more details.
+
+    You should have received a copy of the GNU Lesser General Public
+    License along with this library; if not, write to the Free Software
+    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+Contact: http://eodev.sourceforge.net
+
+Authors:
+    Benjamin Bouvier <benjamin.bouvier@gmail.com>
+*/
+# ifndef __EOSERIAL_TRAITS_H__
+# define __EOSERIAL_TRAITS_H__
+
+/**
+ * @file Traits.h
+ *
+ * Traits used for serialization purposes.
+ *
+ * @author Benjamin Bouvier <benjamin.bouvier@gmail.com>
+ */
+
+namespace eoserial
+{
+
+    /**
+     * @brief Trait to know whether Derived is derived from Base or not.
+     *
+     * To know whether A is derived from B, just test the boolean IsDerivedFrom<A, B>::value.
+     *
+     * @see http://www.gotw.ca/publications/mxc++-item-4.htm
+     */
+    template<class Derived, class Base>
+    class IsDerivedFrom
+    {
+        struct no{};
+        struct yes{ no _[2]; };
+
+        static yes Test( Base* something );
+        static no Test( ... );
+
+    public:
+        enum { value = sizeof( Test( static_cast<Derived*>(0) ) ) == sizeof(yes) };
+    };
+
+}
+
+# endif // __EOSERIAL_TRAITS_H__