[ImplementationDefined, implementationDefined] Dummy struct and enum value to

make documenting interfaces easier.

[[Imported from SVN: r6300]]

dune/common/Makefile.am

@@ -29,6 +29,7 @@ commoninclude_HEADERS = 			\
 	deprecated.hh				\
 	densematrix.hh				\
 	densevector.hh				\
+	documentation.hh			\
 	dynmatrix.hh				\
 	dynvector.hh				\
 	enumset.hh				\

dune/common/documentation.hh

+// -*- tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+// vi: set et ts=4 sw=2 sts=2:
+
+#ifndef DUNE_COMMON_DOCUMENTATION_HH
+#define DUNE_COMMON_DOCUMENTATION_HH
+
+/** \file
+    \brief Documentation related stuff
+ */
+
+namespace Dune {
+
+  //! Dummy struct used for documentation purposes
+  /**
+   * This struct can be used for documenting interfaces.  One example would
+   * be:
+   * \code
+     // Traits class that determines some property for some other type T
+     template<class T>
+     class SomeTraits {
+     dune_static_assert(AlwaysFalse<T>::value,
+                     "Sorry, SomeTraits must be specialized for all types");
+     public:
+     // The type of some property of T
+     typedef ImplementationDefined type;
+     };
+   *#ifndef DOXYGEN
+     template<>
+     struct SomeTraits<int>
+     typedef ... type;
+     };
+     // ...
+   *#endif // DOXYGEN
+   * \endcode
+   *
+   * \sa implementationDefined
+   */
+  struct ImplementationDefined {};
+
+  //! Dummy integral value used for documentation purposes
+  /**
+   * \var Dune::implementationDefined
+   * \code
+   *#include <dune/common/documentation.hh>
+   * \endcode
+   *
+   * \sa ImplementationDefined
+   */
+  enum { implementationDefined };
+
+}
+
+
+#endif // DUNE_COMMON_DOCUMENTATION_HH