Index: boost/operators.hpp
===================================================================
RCS file: /cvsroot/boost/boost/boost/operators.hpp,v
retrieving revision 1.14
diff -u -r1.14 operators.hpp
--- boost/operators.hpp	26 Feb 2003 21:26:57 -0000	1.14
+++ boost/operators.hpp	27 Feb 2003 10:47:54 -0000
@@ -302,6 +302,21 @@
   }
 };
 
+
+//  bool_testable contributed by Sam Partington, David Abrahams, ------------//
+//  and Daniel Frey.  Original concept taken from shared_ptr by Peter Dimov -//
+
+template <class T, class B = ::boost::detail::empty_base>
+struct bool_testable : B
+{
+  typedef void (bool_testable<T,B>::*unspecified_bool_type)() const;
+  operator unspecified_bool_type() const
+  {
+     return !static_cast<const T&>(*this) ? 0 : reinterpret_cast<unspecified_bool_type>(&bool_testable<T,B>::operator unspecified_bool_type);
+  }
+};
+
+
 //  More operator classes (contributed by Daryle Walker) --------------------//
 //  (NRVO-friendly implementation contributed by Daniel Frey) ---------------//