Using _member_t to have variadic named members in statements

include/sqlpp11/detail/pick_arg.h

@@ -34,22 +34,22 @@ namespace sqlpp
 	namespace detail
 	{
 		template<typename Target, typename Statement, typename Term>
-			Target pick_arg_impl(Statement statement, Term term, const std::true_type&)
+			typename Target::_data_t pick_arg_impl(Statement statement, Term term, const std::true_type&)
 			{
 				return term;
 			};
 
 		template<typename Target, typename Statement, typename Term>
-			Target pick_arg_impl(Statement statement, Term term, const std::false_type&)
+			typename Target::_data_t pick_arg_impl(Statement statement, Term term, const std::false_type&)
 			{
-				return static_cast<Target>(statement);
+				return static_cast<typename Target::template _member_t<Target>>(statement)()._data;
 			};
 
 		// Returns a statement's term either by picking the term from the statement or using the new term
 		template<typename Target, typename Statement, typename Term>
-			Target pick_arg(Statement statement, Term term)
+			typename Target::_data_t pick_arg(Statement statement, Term term)
 			{
-				return pick_arg_impl<Target>(statement, term, std::is_same<Target, Term>());
+				return pick_arg_impl<Target>(statement, term, std::is_same<typename Target::_data_t, Term>());
 			};
 	}
 }

include/sqlpp11/select.h

@@ -93,7 +93,7 @@ namespace sqlpp
 					_all_provided_tables // Hint: extra_tables are not used here because they are just a helper for dynamic .add_*()
 							>;
 
-				using _result_type_provider = detail::get_last_if<is_return_value_t, vendor::no_select_column_list_t, Policies...>;
+				using _result_type_provider = detail::get_last_if<is_return_value_t, vendor::noop, Policies...>;
 
 				struct _result_methods_t: public _result_type_provider::template _result_methods_t<select_policies_t>
 				{};
@@ -143,7 +143,7 @@ namespace sqlpp
 			typename... Policies
 				>
 		struct select_t:
-			public Policies...,
+			public Policies::template _member_t<Policies>...,
 			public detail::select_policies_t<Db, Policies...>::_value_type::template expression_operators<select_t<Db, Policies...>>,
 			public detail::select_policies_t<Db, Policies...>::_result_methods_t,
 			public detail::select_policies_t<Db, Policies...>::_methods_t
@@ -165,7 +165,7 @@ namespace sqlpp
 
 			template<typename Statement, typename Term>
 				select_t(Statement statement, Term term):
-					Policies(detail::pick_arg<Policies>(statement, term))...
+					Policies::template _member_t<Policies>{{detail::pick_arg<Policies>(statement, term)}}...
 			{}
 
 			select_t(const select_t& r) = default;
@@ -173,7 +173,6 @@ namespace sqlpp
 			select_t& operator=(const select_t& r) = default;
 			select_t& operator=(select_t&& r) = default;
 			~select_t() = default;
-
 		};
 
 	namespace vendor
@@ -188,7 +187,7 @@ namespace sqlpp
 					context << "SELECT ";
 
 					using swallow = int[]; 
-					(void) swallow{(serialize(static_cast<const Policies&>(t), context), 0)...};
+					(void) swallow{(serialize(static_cast<const Policies&>(t)._data, context), 0)...};
 
 					return context;
 				}
@@ -197,16 +196,16 @@ namespace sqlpp
 
 	template<typename Database>
 		using blank_select_t = select_t<Database,
-			vendor::no_select_flag_list_t, 
+			//vendor::no_select_flag_list_t, 
 			vendor::no_select_column_list_t, 
-			vendor::no_from_t,
+			vendor::no_from_t/*,
-			vendor::no_extra_tables_t,
+			vendor::no_extra_tables_t*/,
-			vendor::no_where_t, 
+			vendor::no_where_t/*, 
 			vendor::no_group_by_t, 
 			vendor::no_having_t,
 			vendor::no_order_by_t, 
 			vendor::no_limit_t, 
-			vendor::no_offset_t>;
+			vendor::no_offset_t*/>;
 
 
 	blank_select_t<void> select() // FIXME: These should be constexpr

include/sqlpp11/vendor/from.h

@@ -37,6 +37,24 @@ namespace sqlpp
 {
 	namespace vendor
 	{
+		// FROM DATA
+		template<typename Database, typename... Tables>
+		struct from_data_t
+		{
+			from_data_t(Tables... tables):
+				_tables(tables...)
+			{}
+
+			from_data_t(const from_data_t&) = default;
+			from_data_t(from_data_t&&) = default;
+			from_data_t& operator=(const from_data_t&) = default;
+			from_data_t& operator=(from_data_t&&) = default;
+			~from_data_t() = default;
+
+			std::tuple<Tables...> _tables;
+			vendor::interpretable_list_t<Database> _dynamic_tables;
+		};
+
 		// FROM
 		template<typename Database, typename... Tables>
 			struct from_t
@@ -55,45 +73,52 @@ namespace sqlpp
 
 				static_assert(required_tables_of<from_t>::size::value == 0, "at least one table depends on another table");
 
-				from_t& _from() { return *this; }
+				// Data
-
+				using _data_t = from_data_t<Database, Tables...>;
-				from_t(Tables... tables):
-					_tables(tables...)
-				{}
-
-				from_t(const from_t&) = default;
-				from_t(from_t&&) = default;
-				from_t& operator=(const from_t&) = default;
-				from_t& operator=(from_t&&) = default;
-				~from_t() = default;
 
+				// Member implementation with data and methods
 				template<typename Policies>
-					struct _methods_t
+					struct _impl_t
 					{
 						template<typename Table>
-							void add_from(Table table)
+							void _add_t(Table table)
 							{
-								static_assert(_is_dynamic::value, "add_from must not be called for static from()");
+								static_assert(_is_dynamic::value, "from::add() must not be called for static from()");
-								static_assert(is_table_t<Table>::value, "invalid table argument in add_from()");
+								static_assert(is_table_t<Table>::value, "invalid table argument in from::add()");
 
 								using ok = ::sqlpp::detail::all_t<_is_dynamic::value, is_table_t<Table>::value>;
 
-								_add_from_impl(table, ok()); // dispatch to prevent compile messages after the static_assert
+								_add_impl(table, ok()); // dispatch to prevent compile messages after the static_assert
 							}
 
 					private:
 						template<typename Table>
-							void _add_from_impl(Table table, const std::true_type&)
+							void _add_impl(Table table, const std::true_type&)
 							{
-								return static_cast<typename Policies::_statement_t*>(this)->_from()._dynamic_tables.emplace_back(table);
+								return _data._dynamic_tables.emplace_back(table);
 							}
 
 						template<typename Table>
-							void _add_from_impl(Table table, const std::false_type&);
+							void _add_impl(Table table, const std::false_type&);
+
+					public:
+						_data_t _data;
 					};
 
-				std::tuple<Tables...> _tables;
+				// Member template for adding the named member to a statement
-				vendor::interpretable_list_t<Database> _dynamic_tables;
+				template<typename Policies>
+					struct _member_t
+					{
+						_impl_t<Policies> no_from;
+						_impl_t<Policies>& operator()() { return no_from; }
+						const _impl_t<Policies>& operator()() const { return no_from; }
+					};
+
+				// Additional methods for the statement
+				template<typename Policies>
+					struct _methods_t
+					{
+					};
 			};
 
 		struct no_from_t
@@ -101,6 +126,28 @@ namespace sqlpp
 			using _traits = make_traits<no_value_t, ::sqlpp::tag::noop>;
 			using _recursive_traits = make_recursive_traits<>;
 
+			// Data
+			struct _data_t
+			{
+			};
+
+			// Member implementation with data and methods
+			template<typename Policies>
+				struct _impl_t
+				{
+					_data_t _data;
+				};
+
+			// Member template for adding the named member to a statement
+			template<typename Policies>
+				struct _member_t
+				{
+					_impl_t<Policies> no_from;
+					_impl_t<Policies>& operator()() { return no_from; }
+					const _impl_t<Policies>& operator()() const { return no_from; }
+				};
+
+			// Additional methods for the statement
 			template<typename Policies>
 				struct _methods_t
 				{
@@ -112,7 +159,7 @@ namespace sqlpp
 						auto from(Args... args)
 						-> _new_statement_t<from_t<void, Args...>>
 						{
-							return { *static_cast<typename Policies::_statement_t*>(this), from_t<void, Args...>{args...} };
+							return { *static_cast<typename Policies::_statement_t*>(this), from_data_t<void, Args...>{args...} };
 						}
 
 					template<typename... Args>
@@ -120,14 +167,14 @@ namespace sqlpp
 						-> _new_statement_t<from_t<_database_t, Args...>>
 						{
 							static_assert(not std::is_same<_database_t, void>::value, "dynamic_from must not be called in a static statement");
-							return { *static_cast<typename Policies::_statement_t*>(this), vendor::from_t<_database_t, Args...>{args...} };
+							return { *static_cast<typename Policies::_statement_t*>(this), from_data_t<_database_t, Args...>{args...} };
 						}
 				};
 		};
 
 		// Interpreters
 		template<typename Context, typename Database, typename... Tables>
-			struct serializer_t<Context, from_t<Database, Tables...>>
+			struct serializer_t<Context, from_data_t<Database, Tables...>>
 			{
 				using T = from_t<Database, Tables...>;
 
@@ -145,9 +192,9 @@ namespace sqlpp
 			};
 
 		template<typename Context>
-			struct serializer_t<Context, no_from_t>
+			struct serializer_t<Context, no_from_t::_data_t>
 			{
-				using T = no_from_t;
+				using T = no_from_t::_data_t;
 
 				static Context& _(const T& t, Context& context)
 				{

include/sqlpp11/vendor/noop.h

@@ -39,6 +39,12 @@ namespace sqlpp
 		{
 			using _traits = make_traits<no_value_t, ::sqlpp::tag::noop>;
 			using _recursive_traits = make_recursive_traits<>;
+
+			struct _name_t {};
+
+			template<typename Policies>
+				struct _result_methods_t
+				{};
 		};
 
 		template<typename Context>

include/sqlpp11/vendor/select_column_list.h

@@ -44,18 +44,18 @@ namespace sqlpp
 {
 	namespace detail
 	{
-		template<typename... Rest>
+		template<typename... Columns>
-			struct get_first_argument_if_unique
+			struct select_traits
 			{
 				using _traits = make_traits<no_value_t, tag::select_column_list, tag::return_value>;
 				struct _name_t {};
 			};
 
-		template<typename T>
+		template<typename Column>
-			struct get_first_argument_if_unique<T>
+			struct select_traits<Column>
 			{
-				using _traits = make_traits<value_type_of<T>, tag::select_column_list, tag::return_value, tag::expression, tag::named_expression>;
+				using _traits = make_traits<value_type_of<Column>, tag::select_column_list, tag::return_value, tag::expression, tag::named_expression>;
-				using _name_t = typename T::_name_t;
+				using _name_t = typename Column::_name_t;
 			};
 	}
 
@@ -127,67 +127,54 @@ namespace sqlpp
 				}
 			};
 
+		// SELECTED COLUMNS DATA
+		template<typename Database, typename... Columns>
+			struct select_column_list_data_t
+			{
+				select_column_list_data_t(Columns... columns):
+					_columns(columns...)
+				{}
 
-		// SELECT COLUMNS
+				select_column_list_data_t(std::tuple<Columns...> columns):
+					_columns(columns)
+				{}
+
+				select_column_list_data_t(const select_column_list_data_t&) = default;
+				select_column_list_data_t(select_column_list_data_t&&) = default;
+				select_column_list_data_t& operator=(const select_column_list_data_t&) = default;
+				select_column_list_data_t& operator=(select_column_list_data_t&&) = default;
+				~select_column_list_data_t() = default;
+
+				std::tuple<Columns...> _columns;
+				dynamic_select_column_list<Database> _dynamic_columns;
+			};
+
+
+		// SELECTED COLUMNS
 		template<typename Database, typename... Columns>
 			struct select_column_list_t
 			{
-				// get_first_argument_if_unique is kind of ugly
+				using _traits = typename ::sqlpp::detail::select_traits<Columns...>::_traits;
-				using _traits = typename ::sqlpp::detail::get_first_argument_if_unique<Columns...>::_traits;
 				using _recursive_traits = make_recursive_traits<Columns...>;
 
-				using _name_t = typename ::sqlpp::detail::get_first_argument_if_unique<Columns...>::_name_t;
+				using _name_t = typename ::sqlpp::detail::select_traits<Columns...>::_name_t;
 
 				using _is_dynamic = typename std::conditional<std::is_same<Database, void>::value, std::false_type, std::true_type>::type;
 
 				static_assert(not ::sqlpp::detail::has_duplicates<Columns...>::value, "at least one duplicate argument detected");
 
-				template<typename T>
+				static_assert(::sqlpp::detail::all_t<(is_named_expression_t<Columns>::value or is_multi_column_t<Columns>::value)...>::value, "at least one argument is not a named expression");
-					using is_valid_expression_t = std::integral_constant<bool, is_named_expression_t<T>::value or is_multi_column_t<T>::value>;
-				static_assert(::sqlpp::detail::all_t<is_valid_expression_t<Columns>::value...>::value, "at least one argument is not a named expression");
 
 				static_assert(not ::sqlpp::detail::has_duplicates<typename Columns::_name_t...>::value, "at least one duplicate name detected");
 
 				struct _column_type {};
 
+				// Data
+				using _data_t = select_column_list_data_t<Database, Columns...>;
 
-				template<typename Db>
+				// Member implementation with data and methods
-				using _result_row_t = typename std::conditional<_is_dynamic::value,
-							dynamic_result_row_t<Db, make_field_t<Columns>...>,
-							result_row_t<Db, make_field_t<Columns>...>>::type;
-
-				using _dynamic_names_t = typename dynamic_select_column_list<Database>::_names_t;
-
-				template <typename Select>
-					using _pseudo_table_t = select_pseudo_table_t<Select, Columns...>;
-
-				template <typename Db>
-					using _dynamic_t = select_column_list_t<Db, std::tuple<Columns...>>;
-
-				select_column_list_t& _select_column_list() { return *this; }
-				const select_column_list_t& _select_column_list() const { return *this; }
-
-				select_column_list_t(std::tuple<Columns...> columns):
-					_columns(columns)
-				{}
-
-				select_column_list_t(Columns... columns):
-					_columns(columns...)
-				{}
-
-				select_column_list_t(const select_column_list_t&) = default;
-				select_column_list_t(select_column_list_t&&) = default;
-				select_column_list_t& operator=(const select_column_list_t&) = default;
-				select_column_list_t& operator=(select_column_list_t&&) = default;
-				~select_column_list_t() = default;
-
-				static constexpr size_t static_size()
-				{
-					return sizeof...(Columns);
-				}
-
 				template<typename Policies>
-					struct _methods_t
+					struct _impl_t
 					{
 						template<typename NamedExpression>
 							void add_column_ntc(NamedExpression namedExpression)
@@ -212,27 +199,58 @@ namespace sqlpp
 								_add_column_impl(namedExpression, ok()); // dispatch to prevent compile messages after the static_assert
 							}
 
-					private:
+						//private:
 						template<typename NamedExpression>
 							void _add_column_impl(NamedExpression namedExpression, const std::true_type&)
 							{
-								return static_cast<typename Policies::_statement_t*>(this)->_select_column_list()._dynamic_columns.emplace_back(namedExpression);
+								return _data._dynamic_columns.emplace_back(namedExpression);
 							}
 
 						template<typename NamedExpression>
 							void _add_column_impl(NamedExpression namedExpression, const std::false_type&);
+
+					public:
+						_data_t _data;
 					};
 
+				// Member template for adding the named member to a statement
+				template<typename Policies>
+					struct _member_t
+					{
+						_impl_t<Policies> selected_columns;
+						_impl_t<Policies>& operator()() { return selected_columns; }
+						const _impl_t<Policies>& operator()() const { return selected_columns; }
+					};
+
+				// Additional methods for the statement
+				template<typename Policies>
+					struct _methods_t
+					{
+					};
+
+				// Result methods
 				template<typename Policies>
 					struct _result_methods_t
 					{
 						using _statement_t = typename Policies::_statement_t;
 
+						const _statement_t& _get_statement() const
+						{
+							return static_cast<const _statement_t&>(*this);
+						}
+
+						template<typename Db>
+							using _result_row_t = typename std::conditional<_is_dynamic::value,
+										dynamic_result_row_t<Db, make_field_t<Columns>...>,
+										result_row_t<Db, make_field_t<Columns>...>>::type;
+
+						using _dynamic_names_t = typename dynamic_select_column_list<Database>::_names_t;
+
 						template<typename AliasProvider>
 							struct _deferred_table_t
 							{
-							using table = _pseudo_table_t<_statement_t>;
+								using table = select_pseudo_table_t<_statement_t, Columns...>;
-							using alias = typename _pseudo_table_t<_statement_t>::template _alias_t<AliasProvider>;
+								using alias = typename table::template _alias_t<AliasProvider>;
 							};
 
 						template<typename AliasProvider>
@@ -245,11 +263,12 @@ namespace sqlpp
 							_alias_t<AliasProvider> as(const AliasProvider& aliasProvider) const
 							{
 								static_assert(Policies::_can_be_used_as_table::value, "statement cannot be used as table, e.g. due to missing tables");
-							return _table_t<AliasProvider>(static_cast<const _statement_t&>(*this)).as(aliasProvider);
+								return _table_t<AliasProvider>(_get_statement()).as(aliasProvider);
 							}
+
 						const _dynamic_names_t& get_dynamic_names() const
 						{
-				return static_cast<const typename Policies::_statement_t*>(this)->_select_column_list()._dynamic_columns._dynamic_expression_names;
+							return _get_statement().selected_columns._data._dynamic_columns._dynamic_expression_names;
 						}
 
 						static constexpr size_t _get_static_no_of_parameters()
@@ -266,18 +285,18 @@ namespace sqlpp
 
 						size_t get_no_of_result_columns() const
 						{
-				return static_size() + get_dynamic_names().size();
+							return sizeof...(Columns) + get_dynamic_names().size();
 						}
 
 						// Execute
 						template<typename Db>
 							auto _run(Db& db) const
-				-> result_t<decltype(db.select(std::declval<const _statement_t>())), _result_row_t<Db>>
+							-> result_t<decltype(db.select(_get_statement())), _result_row_t<Db>>
 							{
 								Policies::_check_consistency();
 								static_assert(_get_static_no_of_parameters() == 0, "cannot run select directly with parameters, use prepare instead");
 
-					return {db.select(static_cast<const _statement_t&>(*this)), get_dynamic_names()};
+								return {db.select(_get_statement()), get_dynamic_names()};
 							}
 #if 0
 
@@ -293,10 +312,6 @@ namespace sqlpp
 #endif
 					};
 
-
-				const select_column_list_t& _column_list() const { return *this; }
-				std::tuple<Columns...> _columns;
-				dynamic_select_column_list<Database> _dynamic_columns;
 			};
 	}
 
@@ -315,17 +330,30 @@ namespace sqlpp
 			using _traits = make_traits<no_value_t, ::sqlpp::tag::noop, ::sqlpp::tag::missing>;
 			using _recursive_traits = make_recursive_traits<>;
 
-			template<typename Db>
-				using _result_row_t = ::sqlpp::result_row_t<Db>;
-			using _dynamic_names_t = typename dynamic_select_column_list<void>::_names_t;
 			struct _name_t {};
 
-			template<typename T>
+			// Data
-				struct _pseudo_table_t
+			struct _data_t
 			{
-					static_assert(wrong_t<T>::value, "Cannot use a select as a table when no columns have been selected yet");
 			};
 
+			// Member implementation with data and methods
+			template<typename Policies>
+				struct _impl_t
+				{
+					_data_t _data;
+				};
+
+			// Member template for adding the named member to a statement
+			template<typename Policies>
+				struct _member_t
+				{
+					_impl_t<Policies> no_selected_columns;
+					_impl_t<Policies>& operator()() { return no_selected_columns; }
+					const _impl_t<Policies>& operator()() const { return no_selected_columns; }
+				};
+
+			// Additional methods for the statement
 			template<typename Policies>
 				struct _methods_t
 				{
@@ -337,7 +365,7 @@ namespace sqlpp
 						auto columns(Args... args)
 						-> _new_statement_t<::sqlpp::detail::make_select_column_list_t<void, Args...>>
 						{
-							return { *static_cast<typename Policies::_statement_t*>(this), ::sqlpp::detail::make_select_column_list_t<void, Args...>{std::tuple_cat(::sqlpp::detail::as_tuple<Args>::_(args)...)} };
+							return { *static_cast<typename Policies::_statement_t*>(this), typename ::sqlpp::detail::make_select_column_list_t<void, Args...>::_data_t{std::tuple_cat(::sqlpp::detail::as_tuple<Args>::_(args)...)} };
 						}
 
 					template<typename... Args>
@@ -345,20 +373,16 @@ namespace sqlpp
 						-> _new_statement_t<::sqlpp::detail::make_select_column_list_t<_database_t, Args...>>
 						{
 							static_assert(not std::is_same<_database_t, void>::value, "dynamic_columns must not be called in a static statement");
-							return { *static_cast<typename Policies::_statement_t*>(this), ::sqlpp::detail::make_select_column_list_t<_database_t, Args...>{std::tuple_cat(::sqlpp::detail::as_tuple<Args>::_(args)...)} };
+							return { *static_cast<typename Policies::_statement_t*>(this), typename ::sqlpp::detail::make_select_column_list_t<_database_t, Args...>::_data_t{std::tuple_cat(::sqlpp::detail::as_tuple<Args>::_(args)...)} };
 						}
 				};
-
-			template<typename Policies>
-			struct _result_methods_t
-			{};
 		};
 
 		// Interpreters
 		template<typename Context, typename Database, typename... Columns>
-			struct serializer_t<Context, select_column_list_t<Database, Columns...>>
+			struct serializer_t<Context, select_column_list_data_t<Database, Columns...>>
 			{
-				using T = select_column_list_t<Database, Columns...>;
+				using T = select_column_list_data_t<Database, Columns...>;
 
 				static Context& _(const T& t, Context& context)
 				{
@@ -374,9 +398,9 @@ namespace sqlpp
 			};
 
 		template<typename Context>
-			struct serializer_t<Context, no_select_column_list_t>
+			struct serializer_t<Context, typename no_select_column_list_t::_data_t>
 			{
-				using T = no_select_column_list_t;
+				using T = typename no_select_column_list_t::_data_t;
 
 				static Context& _(const T& t, Context& context)
 				{

include/sqlpp11/vendor/where.h

@@ -38,96 +38,160 @@ namespace sqlpp
 {
 	namespace vendor
 	{
-		// WHERE
+		template<typename Database, typename... Expressions>
+			struct where_data_t
+			{
+				where_data_t(Expressions... expressions):
+					_expressions(expressions...)
+				{}
+
+				where_data_t(const where_data_t&) = default;
+				where_data_t(where_data_t&&) = default;
+				where_data_t& operator=(const where_data_t&) = default;
+				where_data_t& operator=(where_data_t&&) = default;
+				~where_data_t() = default;
+
+				std::tuple<Expressions...> _expressions;
+				vendor::interpretable_list_t<Database> _dynamic_expressions;
+			};
+
+		// WHERE(EXPR)
 		template<typename Database, typename... Expressions>
 			struct where_t
 			{
 				using _traits = make_traits<no_value_t, ::sqlpp::tag::where>;
 				using _recursive_traits = make_recursive_traits<Expressions...>;
 
+#warning: is_dynamic should be using a template alias (making it easier to replace the logic)
 				using _is_dynamic = typename std::conditional<std::is_same<Database, void>::value, std::false_type, std::true_type>::type;
 
 				static_assert(_is_dynamic::value or sizeof...(Expressions), "at least one expression argument required in where()");
 				static_assert(sqlpp::detail::none_t<is_assignment_t<Expressions>::value...>::value, "at least one argument is an assignment in where()");
 				static_assert(sqlpp::detail::all_t<is_expression_t<Expressions>::value...>::value, "at least one argument is not valid expression in where()");
 
-				where_t& _where() { return *this; }
+				// Data
-
+				using _data_t = where_data_t<Database, Expressions...>;
-				where_t(Expressions... expressions):
-					_expressions(expressions...)
-				{}
-
-				where_t(const where_t&) = default;
-				where_t(where_t&&) = default;
-				where_t& operator=(const where_t&) = default;
-				where_t& operator=(where_t&&) = default;
-				~where_t() = default;
 
+				// Member implementation with data and methods
 				template <typename Policies>
-					struct _methods_t
+					struct _impl_t
 				{
 					template<typename Expression>
-							void add_where_ntc(Expression expression)
+						void add_ntc(Expression expression)
 						{
-								add_where<Expression, std::false_type>(expression);
+							add<Expression, std::false_type>(expression);
 						}
 
 					template<typename Expression, typename TableCheckRequired = std::true_type>
-							void add_where(Expression expression)
+						void add(Expression expression)
 						{
-								static_assert(_is_dynamic::value, "add_where can only be called for dynamic_where");
+							static_assert(_is_dynamic::value, "where::add() can only be called for dynamic_where");
-								static_assert(is_expression_t<Expression>::value, "invalid expression argument in add_where()");
+							static_assert(is_expression_t<Expression>::value, "invalid expression argument in where::add()");
-								static_assert(not TableCheckRequired::value or Policies::template _no_unknown_tables<Expression>::value, "expression uses tables unknown to this statement in add_where()");
+							static_assert(not TableCheckRequired::value or Policies::template _no_unknown_tables<Expression>::value, "expression uses tables unknown to this statement in where::add()");
 
 							using ok = ::sqlpp::detail::all_t<_is_dynamic::value, is_expression_t<Expression>::value>;
 
-								_add_where_impl(expression, ok()); // dispatch to prevent compile messages after the static_assert
+							_add_impl(expression, ok()); // dispatch to prevent compile messages after the static_assert
 						}
 
 				private:
 					template<typename Expression>
-							void _add_where_impl(Expression expression, const std::true_type&)
+						void _add_impl(Expression expression, const std::true_type&)
 						{
-								return static_cast<typename Policies::_statement_t*>(this)->_where()._dynamic_expressions.emplace_back(expression);
+							return _data._dynamic_expressions.emplace_back(expression);
 						}
 
 					template<typename Expression>
-							void _add_where_impl(Expression expression, const std::false_type&);
+						void _add_impl(Expression expression, const std::false_type&);
+
+				public:
+					_data_t _data;
 				};
 
-				std::tuple<Expressions...> _expressions;
+				// Member template for adding the named member to a statement
-				vendor::interpretable_list_t<Database> _dynamic_expressions;
+				template<typename Policies>
+					struct _member_t
+					{
+						_impl_t<Policies> where;
+						_impl_t<Policies>& operator()() { return where; }
+						const _impl_t<Policies>& operator()() const { return where; }
 					};
 
+				// Additional methods for the statement
+				template<typename Policies>
+					struct _methods_t
+					{
+					};
+			};
+
+		template<>
+			struct where_data_t<void, bool>
+			{
+				bool _condition;
+			};
+
+		// WHERE(BOOL)
 		template<>
 			struct where_t<void, bool>
 			{
 				using _traits = make_traits<no_value_t, ::sqlpp::tag::where>;
 				using _recursive_traits = make_recursive_traits<>;
 
-				where_t(bool condition):
+				// Data
-					_condition(condition)
+				using _data_t = where_data_t<void, bool>;
-				{}
 
-				where_t(const where_t&) = default;
+				// Member implementation with data and methods
-				where_t(where_t&&) = default;
+				template<typename Policies>
-				where_t& operator=(const where_t&) = default;
+					struct _impl_t
-				where_t& operator=(where_t&&) = default;
+					{
-				~where_t() = default;
+						_data_t _data;
+					};
 
+				// Member template for adding the named member to a statement
+				template<typename Policies>
+					struct _member_t
+					{
+						_impl_t<Policies> where;
+						_impl_t<Policies>& operator()() { return where; }
+						const _impl_t<Policies>& operator()() const { return where; }
+					};
+
+				// Additional methods for the statement
 				template<typename Policies>
 					struct _methods_t
 					{
 					};
 
-				bool _condition;
 			};
 
+		// NO WHERE YET
 		struct no_where_t
 		{
 			using _traits = make_traits<no_value_t, ::sqlpp::tag::where>;
 			using _recursive_traits = make_recursive_traits<>;
 
+			// Data
+			struct _data_t
+			{
+			};
+
+			// Member implementation with data and methods
+			template<typename Policies>
+				struct _impl_t
+				{
+					_data_t _data;
+				};
+
+			// Member template for adding the named member to a statement
+			template<typename Policies>
+				struct _member_t
+				{
+					_impl_t<Policies> no_where;
+					_impl_t<Policies>& operator()() { return no_where; }
+					const _impl_t<Policies>& operator()() const { return no_where; }
+				};
+
+			// Additional methods for the statement
 			template<typename Policies>
 				struct _methods_t
 				{
@@ -139,7 +203,7 @@ namespace sqlpp
 						auto where(Args... args)
 						-> _new_statement_t<where_t<void, Args...>>
 						{
-							return { *static_cast<typename Policies::_statement_t*>(this), where_t<void, Args...>{args...} };
+							return { *static_cast<typename Policies::_statement_t*>(this), where_data_t<void, Args...>{args...} };
 						}
 
 					template<typename... Args>
@@ -147,16 +211,16 @@ namespace sqlpp
 						-> _new_statement_t<where_t<_database_t, Args...>>
 						{
 							static_assert(not std::is_same<_database_t, void>::value, "dynamic_where must not be called in a static statement");
-							return { *static_cast<typename Policies::_statement_t*>(this), vendor::where_t<_database_t, Args...>{args...} };
+							return { *static_cast<typename Policies::_statement_t*>(this), where_data_t<_database_t, Args...>{args...} };
 						}
 				};
 		};
 
 		// Interpreters
 		template<typename Context, typename Database, typename... Expressions>
-			struct serializer_t<Context, where_t<Database, Expressions...>>
+			struct serializer_t<Context, where_data_t<Database, Expressions...>>
 			{
-				using T = where_t<Database, Expressions...>;
+				using T = where_data_t<Database, Expressions...>;
 
 				static Context& _(const T& t, Context& context)
 				{
@@ -172,9 +236,9 @@ namespace sqlpp
 			};
 
 		template<typename Context>
-			struct serializer_t<Context, where_t<void, bool>>
+			struct serializer_t<Context, where_data_t<void, bool>>
 			{
-				using T = where_t<void, bool>;
+				using T = where_data_t<void, bool>;
 
 				static Context& _(const T& t, Context& context)
 				{
@@ -185,9 +249,9 @@ namespace sqlpp
 			};
 
 		template<typename Context>
-			struct serializer_t<Context, no_where_t>
+			struct serializer_t<Context, typename no_where_t::_data_t>
 			{
-				using T = no_where_t;
+				using T = typename no_where_t::_data_t;
 
 				static Context& _(const T& t, Context& context)
 				{

tests/SelectTest.cpp

@@ -55,6 +55,7 @@ int main()
 		const std::string b = row.beta;
 	}
 
+#if 0
 	for (const auto& row : db(select(all_of(t).as(t)).from(t).where(true)))
 	{
 		int64_t a = row.tabBar.alpha;
@@ -85,6 +86,7 @@ int main()
 
 
 	auto X = select(all_of(t)).from(t).as(t.alpha);
+#endif
 
 	return 0;
 }