diff --git a/src/libraries/turtle/expectation.hpp b/src/libraries/turtle/expectation.hpp
index fc3a8c4..c3937a5 100644
--- a/src/libraries/turtle/expectation.hpp
+++ b/src/libraries/turtle/expectation.hpp
@@ -32,172 +32,229 @@ namespace mock
               typename ErrorPolicy = boost_test_error_policy<
                   BOOST_DEDUCED_TYPENAME boost::function<
                       Signature >::result_type > > // $$$$ MAT : concept check Signature is actually a signature
-    class expectation : private verifiable
+    class expectation
     {
     public:
         typedef BOOST_DEDUCED_TYPENAME
             boost::function< Signature >::result_type result_type;
+
+    private:
         typedef detail::matcher< result_type,
                                  Signature,
                                  ErrorPolicy,
                                  boost::function< Signature >::arity >
                 matcher_type;
 
+    public:
         expectation( node& parent = root, const std::string& name = "?" )
-            : name_( name )
-            , parent_( &parent )
-            , valid_( true )
-        {
-            parent_->add( *this );
-        }
+            : impl_( new expectation_impl( parent, name ) )
+        {}
         expectation( const std::string& name )
-            : name_( name )
-            , parent_( &root )
-            , valid_( true )
-        {
-            parent_->add( *this );
-        }
-        virtual ~expectation()
-        {
-            parent_->remove( *this );
-            if( ! std::uncaught_exception() )
-                for( matchers_cit it = matchers_.begin();
-                    it != matchers_.end(); ++it )
-                    if( valid_ && ! it->verify() )
-                        ErrorPolicy::untriggered_expectation(
-                            context(), it->file(), it->line() );
-        }
+            : impl_( new expectation_impl( root, name ) )
+        {}
 
         expectation& set_name( const std::string& name )
         {
-            name_ = name;
+            impl_->set_name( name );
             return *this;
         }
         expectation& set_parent( node& parent )
         {
-            parent_->remove( *this );
-            parent.add( *this );
-            parent_ = &parent;
+            impl_->set_parent( parent );
             return *this;
         }
 
-        virtual bool verify()
+        bool verify()
         {
-            for( matchers_cit it = matchers_.begin();
-                it != matchers_.end(); ++it )
-                if( !it->verify() )
-                {
-                    valid_ = false;
-                    ErrorPolicy::verification_failed( context(),
-                        it->file(), it->line() );
-                }
-            return valid_;
+            return impl_->verify();
         }
-        virtual void reset()
+        void reset()
         {
-            valid_ = true;
-            matchers_.clear();
+            impl_->reset();
         }
 
         matcher_type& expect( const std::string& file, int line )
         {
-            matchers_.push_back( matcher_type() );
-            matchers_.back().set_location( file, line );
-            valid_ = true;
-            return matchers_.back();
+            return impl_->expect( file, line );
         }
         matcher_type& expect()
         {
-            matchers_.push_back( matcher_type() );
-            valid_ = true;
-            return matchers_.back();
+            return impl_->expect();
         }
 
         result_type operator()() const
         {
-            for( matchers_cit it = matchers_.begin();
-                it != matchers_.end(); ++it )
-                if( it->is_valid() )
-                {
-                    if( !it->invoke() )
+            return (*impl_)();
+        }
+
+#define MOCK_EXPECTATION_OPERATOR(z, n, d) \
+        template< BOOST_PP_ENUM_PARAMS(n, typename A) > \
+        result_type operator()( BOOST_PP_ENUM_BINARY_PARAMS(n, const A, & a) ) const \
+        { \
+            return (*impl_)( BOOST_PP_ENUM_PARAMS(n, a) ); \
+        }
+        BOOST_PP_REPEAT_FROM_TO(1, MOCK_MAX_ARGS, MOCK_EXPECTATION_OPERATOR, BOOST_PP_EMPTY)
+#undef MOCK_EXPECTATION_OPERATOR
+
+        friend std::ostream& operator<<( std::ostream& s, const expectation& e )
+        {
+            return s << *e.impl_;
+        }
+
+    private:
+        class expectation_impl : private verifiable
+        {
+        public:
+            expectation_impl( node& parent, const std::string& name )
+                : name_( name )
+                , parent_( &parent )
+                , valid_( true )
+            {
+                parent_->add( *this );
+            }
+            virtual ~expectation_impl()
+            {
+                parent_->remove( *this );
+                if( ! std::uncaught_exception() )
+                    for( matchers_cit it = matchers_.begin();
+                        it != matchers_.end(); ++it )
+                        if( valid_ && ! it->verify() )
+                            ErrorPolicy::untriggered_expectation(
+                                context(), it->file(), it->line() );
+            }
+
+            void set_name( const std::string& name )
+            {
+                name_ = name;
+            }
+            void set_parent( node& parent )
+            {
+                parent_->remove( *this );
+                parent.add( *this );
+                parent_ = &parent;
+            }
+
+            virtual bool verify()
+            {
+                for( matchers_cit it = matchers_.begin();
+                    it != matchers_.end(); ++it )
+                    if( !it->verify() )
                     {
                         valid_ = false;
-                        ErrorPolicy::sequence_failed( context( "" ),
+                        ErrorPolicy::verification_failed( context(),
                             it->file(), it->line() );
                     }
-                    return it->functor()();
-                }
-            valid_ = false;
-            return ErrorPolicy::no_match( context( "" ) );
-        }
+                return valid_;
+            }
+            virtual void reset()
+            {
+                valid_ = true;
+                matchers_.clear();
+            }
+
+            matcher_type& expect( const std::string& file, int line )
+            {
+                matchers_.push_back( matcher_type() );
+                matchers_.back().set_location( file, line );
+                valid_ = true;
+                return matchers_.back();
+            }
+            matcher_type& expect()
+            {
+                matchers_.push_back( matcher_type() );
+                valid_ = true;
+                return matchers_.back();
+            }
+
+            result_type operator()() const
+            {
+                for( matchers_cit it = matchers_.begin();
+                    it != matchers_.end(); ++it )
+                    if( it->is_valid() )
+                    {
+                        if( !it->invoke() )
+                        {
+                            valid_ = false;
+                            ErrorPolicy::sequence_failed( context( "" ),
+                                it->file(), it->line() );
+                        }
+                        return it->functor()();
+                    }
+                valid_ = false;
+                return ErrorPolicy::no_match( context( "" ) );
+            }
 
 #define MOCK_EXPECTATION_PARAMETER(z, n, d) BOOST_PP_COMMA_IF(n) const_cast< A##n & >( a##n )
 #define MOCK_EXPECTATION_DETAIL(z, n, d) + ", " + format( a##n )
 #define MOCK_EXPECTATION_PARAMETERS(n) \
     format( a0 ) BOOST_PP_REPEAT_FROM_TO(1, n, MOCK_EXPECTATION_DETAIL, BOOST_PP_EMPTY)
 #define MOCK_EXPECTATION_OPERATOR(z, n, d) \
-        template< BOOST_PP_ENUM_PARAMS(n, typename A) > \
-        result_type operator()( BOOST_PP_ENUM_BINARY_PARAMS(n, const A, & a) ) const \
-        { \
-            for( matchers_cit it = matchers_.begin(); it != matchers_.end(); ++it ) \
-                if( it->is_valid( BOOST_PP_REPEAT_FROM_TO(0, n, MOCK_EXPECTATION_PARAMETER, BOOST_PP_EMPTY) ) ) \
-                { \
-                    if( !it->invoke() ) \
+            template< BOOST_PP_ENUM_PARAMS(n, typename A) > \
+            result_type operator()( BOOST_PP_ENUM_BINARY_PARAMS(n, const A, & a) ) const \
+            { \
+                for( matchers_cit it = matchers_.begin(); it != matchers_.end(); ++it ) \
+                    if( it->is_valid( BOOST_PP_REPEAT_FROM_TO(0, n, MOCK_EXPECTATION_PARAMETER, BOOST_PP_EMPTY) ) ) \
                     { \
-                        valid_ = false; \
-                        ErrorPolicy::sequence_failed( context( MOCK_EXPECTATION_PARAMETERS(n) ), it->file(), it->line() ); \
+                        if( !it->invoke() ) \
+                        { \
+                            valid_ = false; \
+                            ErrorPolicy::sequence_failed( context( MOCK_EXPECTATION_PARAMETERS(n) ), it->file(), it->line() ); \
+                        } \
+                        return it->functor()( BOOST_PP_REPEAT_FROM_TO(0, n, MOCK_EXPECTATION_PARAMETER, BOOST_PP_EMPTY) ); \
                     } \
-                    return it->functor()( BOOST_PP_REPEAT_FROM_TO(0, n, MOCK_EXPECTATION_PARAMETER, BOOST_PP_EMPTY) ); \
-                } \
-            valid_ = false; \
-            return ErrorPolicy::no_match( context( MOCK_EXPECTATION_PARAMETERS(n) ) ); \
-        }
-        BOOST_PP_REPEAT_FROM_TO(1, MOCK_MAX_ARGS, MOCK_EXPECTATION_OPERATOR, BOOST_PP_EMPTY)
+                valid_ = false; \
+                return ErrorPolicy::no_match( context( MOCK_EXPECTATION_PARAMETERS(n) ) ); \
+            }
+            BOOST_PP_REPEAT_FROM_TO(1, MOCK_MAX_ARGS, MOCK_EXPECTATION_OPERATOR, BOOST_PP_EMPTY)
 #undef MOCK_EXPECTATION_PARAMETER
 #undef MOCK_EXPECTATION_PARAMETERS
 #undef MOCK_EXPECTATION_DETAIL
 #undef MOCK_EXPECTATION_OPERATOR
 
-        friend std::ostream& operator<<( std::ostream& s, const expectation& e )
-        {
-            return s << e.context();
-        }
+            friend std::ostream& operator<<( std::ostream& s, const expectation_impl& e )
+            {
+                return s << e.context();
+            }
+
+        private:
+            typedef std::list< matcher_type > matchers_type;
+            typedef BOOST_DEDUCED_TYPENAME
+                matchers_type::const_iterator matchers_cit;
+
+            void serialize( std::ostream& s ) const
+            {
+                for( matchers_cit it = matchers_.begin();
+                    it != matchers_.end(); ++it )
+                    s << std::endl << *it;
+            }
+
+            std::string context() const
+            {
+                std::stringstream s;
+                s << *parent_ << name_;
+                serialize( s );
+                return s.str();
+            }
+            std::string context( const std::string& parameters ) const
+            {
+                std::stringstream s;
+                s << *parent_ << name_;
+                if( parameters.empty() )
+                    s << "()";
+                else
+                    s << "( " << parameters << " )";
+                serialize( s );
+                return s.str();
+            }
+
+            std::string name_;
+            node* parent_;
+            mutable bool valid_;
+            matchers_type matchers_;
+        };
 
     private:
-        typedef std::list< matcher_type > matchers_type;
-        typedef BOOST_DEDUCED_TYPENAME
-            matchers_type::const_iterator matchers_cit;
-
-        void serialize( std::ostream& s ) const
-        {
-            for( matchers_cit it = matchers_.begin();
-                it != matchers_.end(); ++it )
-                s << std::endl << *it;
-        }
-
-        std::string context() const
-        {
-            std::stringstream s;
-            s << *parent_ << name_;
-            serialize( s );
-            return s.str();
-        }
-        std::string context( const std::string& parameters ) const
-        {
-            std::stringstream s;
-            s << *parent_ << name_;
-            if( parameters.empty() )
-                s << "()";
-            else
-                s << "( " << parameters << " )";
-            serialize( s );
-            return s.str();
-        }
-
-        std::string name_;
-        node* parent_;
-        mutable bool valid_;
-        matchers_type matchers_;
+        boost::shared_ptr< expectation_impl > impl_;
     };
 }
 
diff --git a/src/tests/turtle_test/expectation_test.cpp b/src/tests/turtle_test/expectation_test.cpp
index 08b4f40..f3c1dcb 100644
--- a/src/tests/turtle_test/expectation_test.cpp
+++ b/src/tests/turtle_test/expectation_test.cpp
@@ -26,6 +26,12 @@ namespace
 
 // functor
 
+BOOST_AUTO_TEST_CASE( an_expectation_can_be_passed_as_functor )
+{
+    mock::expectation< void() > e;
+    boost::function< void() > f = e;
+}
+
 BOOST_AUTO_TEST_CASE( an_expectation_can_be_passed_as_functor_using_boost_bind_and_boost_ref )
 {
     mock::expectation< void() > e;