diff --git a/rjp++/CMakeLists.txt b/rjp++/CMakeLists.txt
index e3335f4..7701ec9 100644
--- a/rjp++/CMakeLists.txt
+++ b/rjp++/CMakeLists.txt
@@ -14,7 +14,7 @@ option(BUILD_TESTS "Build test programs" OFF)
 option(ENABLE_PROFILING "Enable asan" OFF)
 mark_as_advanced(ENABLE_PROFILING)
 
-set(SOURCE_LIST "src/allocator.cpp" "src/array.cpp" "src/integral.cpp" "src/object.cpp" "src/rjp.cpp" "src/string.cpp" "src/string_val.cpp" "src/value.cpp" "src/vget_proxy.cpp" "src/container.cpp")
+set(SOURCE_LIST "src/allocator.cpp" "src/array.cpp" "src/integral.cpp" "src/object.cpp" "src/rjp.cpp" "src/string.cpp" "src/string_val.cpp" "src/value.cpp" "src/vget_proxy.cpp" "src/container.cpp" "src/member.cpp")
 if(ENABLE_SHARED)
 	set(RJP++_LIBFLAGS "-lrjp++ -lrexy")
 	add_library(rjp++ SHARED ${SOURCE_LIST})
diff --git a/rjp++/include/array.hpp b/rjp++/include/array.hpp
index 6b60598..23dec44 100644
--- a/rjp++/include/array.hpp
+++ b/rjp++/include/array.hpp
@@ -103,6 +103,8 @@ namespace rjp{
 		iterator end(void);
 		const_iterator begin(void)const;
 		const_iterator end(void)const;
+		const_iterator cbegin(void)const;
+		const_iterator cend(void)const;
 
 		size_type size(void)const;
 
diff --git a/rjp++/include/object.hpp b/rjp++/include/object.hpp
index 84517ef..6c71846 100644
--- a/rjp++/include/object.hpp
+++ b/rjp++/include/object.hpp
@@ -134,7 +134,11 @@ namespace rjp{
 
 		iterator begin(void);
 		const_iterator begin(void)const;
-		iterator end(void)const;
+		iterator end(void);
+		const_iterator end(void)const;
+
+		const_iterator cbegin(void)const;
+		const_iterator cend(void)const;
 
 		size_type size(void)const;
 
diff --git a/rjp++/include/parse.hpp b/rjp++/include/parse.hpp
index 481fca7..ed2987c 100644
--- a/rjp++/include/parse.hpp
+++ b/rjp++/include/parse.hpp
@@ -48,8 +48,11 @@ namespace rjp{
 		string errstr(void)const;
 	};
 
+	[[nodiscard]]
 	string to_json(const value& val, int format = RJP_FORMAT_PRETTY);
+	[[nodiscard]]
 	parse_res parse_json(const rexy::string_base<char>& str, RJP_parse_flag = RJP_PARSE_NO_EXT);
+	[[nodiscard]]
 	parse_res parse_json(const char* str, RJP_parse_flag = RJP_PARSE_NO_EXT);
 	namespace detail{
 		template<int... Indexes>
@@ -91,6 +94,7 @@ namespace rjp{
 		int irjp_parse_callback(char* dest, int size, void* userdata);
 	}
 	template<class Func, class... Args>
+	[[nodiscard]]
 	parse_res parse_json(RJP_parse_flag f, Func&& func, Args&&... args){
 		RJP_parse_callback cb;
 		detail::invoker_impl<Func,Args...> inv(std::forward<Func>(func), std::forward<Args>(args)...);
diff --git a/rjp++/include/rjp_util.hpp b/rjp++/include/rjp_util.hpp
index 047d330..7f99b3b 100644
--- a/rjp++/include/rjp_util.hpp
+++ b/rjp++/include/rjp_util.hpp
@@ -23,60 +23,19 @@
 #include "integral.hpp"
 
 namespace rjp{
-	namespace detail{
-		template<class To, class From, bool = std::is_same<std::remove_reference_t<To>,std::remove_reference_t<From>>::value>
-		struct convert_helper;
-		template<class To, class From>
-		struct convert_helper<To,From,false>{
-			static To perform(From&& t){
-				return To(std::move(t));
-			}
-		};
-		template<class To, class From>
-		struct convert_helper<To,From&,false>{
-			static To perform(const From& t){
-				return To(const_cast<RJP_value*>(t.raw()), false);
-			}
-		};
-		template<class To, class From>
-		struct convert_helper<To,From,true>{
-			static decltype(auto) perform(From&& t){
-				return std::forward<From>(t);
-			}
-		};
+	template<class To, class From>
+	auto convert_to(From&& from){
+		return To(std::forward<From>(from));
 	}
 
 	template<class To, class From>
-	To convert(From&& from){
-		return detail::convert_helper<To,From>::perform(std::forward<From>(from));
-	}
-
-	namespace detail{
-		template<class To, class From>
-		struct get_ref{
-			using type = std::remove_reference_t<To>;
-		};
-		template<class To, class From>
-		struct get_ref<To, From&>{
-			using type = std::remove_reference_t<To>&;
-		};
-		template<class To, class From>
-		struct get_ref<To, From&&>{
-			using type = std::remove_reference_t<To>&&;
-		};
-		template<class To, class From>
-		struct get_ref<To&&, From&>{
-			using type = To&&;
-		};
-		template<class To, class From>
-		struct get_ref<To&&, From&&>{
-			using type = To&&;
-		};
+	auto steal_as(From&& from){
+		return To(std::move(from));
 	}
 
 	template<class To, class From>
-	decltype(auto) cast(From&& from){
-		return static_cast<typename detail::get_ref<To,From&&>::type>(std::forward<From>(from));
+	auto borrow_as(From&& from){
+		return To(const_cast<RJP_value*>(from.raw()), false);
 	}
 
 	namespace detail{
diff --git a/rjp++/src/array.cpp b/rjp++/src/array.cpp
index dff1c29..bac37a3 100644
--- a/rjp++/src/array.cpp
+++ b/rjp++/src/array.cpp
@@ -76,10 +76,19 @@ namespace rjp{
 	array::iterator array::begin(void){
 		return iterator(m_value);
 	}
+	array::iterator array::end(void){
+		return iterator();
+	}
 	array::const_iterator array::begin(void)const{
 		return const_iterator(m_value);
 	}
-	array::iterator array::end(void){
+	array::const_iterator array::end(void)const{
+		return iterator();
+	}
+	array::const_iterator array::cbegin(void)const{
+		return const_iterator(m_value);
+	}
+	array::const_iterator array::cend(void)const{
 		return iterator();
 	}
 	array::size_type array::size(void)const{
diff --git a/rjp++/src/member.cpp b/rjp++/src/member.cpp
new file mode 100644
index 0000000..d551589
--- /dev/null
+++ b/rjp++/src/member.cpp
@@ -0,0 +1,27 @@
+/**
+	rjp++
+	Copyright (C) 2022 rexy712
+
+	This program is free software: you can redistribute it and/or modify
+	it under the terms of the GNU General Public License as published by
+	the Free Software Foundation, either version 3 of the License, or
+	(at your option) any later version.
+
+	This program 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 General Public License for more details.
+
+	You should have received a copy of the GNU General Public License
+	along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#include "member.hpp"
+
+namespace rjp{
+
+	const RJP_string* member_base::member_key(RJP_value* v){
+		return rjp_member_key(v);
+	}
+
+}
diff --git a/rjp++/src/object.cpp b/rjp++/src/object.cpp
index a6e256a..d3485a0 100644
--- a/rjp++/src/object.cpp
+++ b/rjp++/src/object.cpp
@@ -119,9 +119,18 @@ namespace rjp{
 	object::const_iterator object::begin(void)const{
 		return const_iterator(m_value);
 	}
-	object::iterator object::end(void)const{
+	object::iterator object::end(void){
 		return iterator();
 	}
+	object::const_iterator object::end(void)const{
+		return const_iterator();
+	}
+	object::const_iterator object::cbegin(void)const{
+		return const_iterator(m_value);
+	}
+	object::const_iterator object::cend(void)const{
+		return const_iterator();
+	}
 	object::size_type object::size(void)const{
 		return rjp_num_members(m_value);
 	}
diff --git a/rjp++/src/vget_proxy.cpp b/rjp++/src/vget_proxy.cpp
index 72b66fb..daef431 100644
--- a/rjp++/src/vget_proxy.cpp
+++ b/rjp++/src/vget_proxy.cpp
@@ -27,16 +27,16 @@ namespace rjp::detail{
 	vget_proxy::vget_proxy(const rjp::value* v):
 		m_value(v){}
 	vget_proxy::operator int(void)const{
-		return rjp::cast<const rjp::integer>(*m_value).get();
+		return rjp::borrow_as<rjp::integer>(*m_value).get();
 	}
 	vget_proxy::operator bool(void)const{
-		return rjp::cast<const rjp::boolean>(*m_value).get();
+		return rjp::borrow_as<rjp::boolean>(*m_value).get();
 	}
 	vget_proxy::operator rexy::static_string<char>(void)const{
-		return rjp::cast<const rjp::string_val>(*m_value).get();
+		return rjp::borrow_as<rjp::string_val>(*m_value).get();
 	}
 	vget_proxy::operator double(void)const{
-		return rjp::cast<const rjp::dfloat>(*m_value).get();
+		return rjp::borrow_as<rjp::dfloat>(*m_value).get();
 	}
 
 }
diff --git a/rjp++/tests/output.cpp b/rjp++/tests/output.cpp
index 35cbe9c..d9c5d34 100644
--- a/rjp++/tests/output.cpp
+++ b/rjp++/tests/output.cpp
@@ -35,14 +35,14 @@ rjp::value case_6(void){
 rjp::value case_8(void){
 	rjp::object obj;
 	obj.add<rjp::integer>("key"_ss, 7);
-	return rjp::cast<rjp::value&&>(obj);
+	return rjp::steal_as<rjp::value>(obj);
 }
 //handle object with subobject
 rjp::value case_9(void){
 	rjp::object obj;
 	rjp::object sub = obj.add<rjp::object>("key"_ss);
 	sub.add<rjp::boolean>("subkey"_ss, false);
-	return rjp::cast<rjp::value&&>(obj);
+	return rjp::steal_as<rjp::value>(obj);
 }
 //handle object with multiple members
 rjp::value case_10(void){
@@ -50,7 +50,7 @@ rjp::value case_10(void){
 	rjp::object sub = obj.add<rjp::object>("key"_ss);
 	sub.add<rjp::boolean>("subkey"_ss, false);
 	sub.add<rjp::boolean>("subkey2"_ss, true);
-	return rjp::cast<rjp::value&&>(obj);
+	return rjp::steal_as<rjp::value>(obj);
 }
 //handle object member ordering
 rjp::value case_11(void){
@@ -58,7 +58,7 @@ rjp::value case_11(void){
 	rjp::object sub = obj.add<rjp::object>("key"_ss);
 	sub.add<rjp::boolean>("subkey2"_ss, true);
 	sub.add<rjp::boolean>("subkey"_ss, false);
-	return rjp::cast<rjp::value&&>(obj);
+	return rjp::steal_as<rjp::value>(obj);
 }
 //handle orderedobject member ordering
 /*RJP_value* case_12(void){
@@ -82,13 +82,13 @@ RJP_value* case_13(void){
 rjp::value case_14(void){
 	rjp::array arr;
 	arr.add<rjp::integer>(5);
-	return rjp::cast<rjp::value&&>(arr);
+	return rjp::steal_as<rjp::value>(arr);
 }
 //handle array with subarray
 rjp::value case_15(void){
 	rjp::array arr;
 	arr.add<rjp::array>().add<rjp::boolean>(false);
-	return rjp::cast<rjp::value&&>(arr);
+	return rjp::steal_as<rjp::value>(arr);
 }
 //handle array with multiple elements
 rjp::value case_16(void){
@@ -96,7 +96,7 @@ rjp::value case_16(void){
 	rjp::array sub = arr.add<rjp::array>();
 	sub.add<rjp::boolean>(false);
 	sub.add<rjp::boolean>(true);
-	return rjp::cast<rjp::value&&>(arr);
+	return rjp::steal_as<rjp::value>(arr);
 }
 //handle array with multiple elements and subarray
 rjp::value case_17(void){
@@ -105,7 +105,7 @@ rjp::value case_17(void){
 	rjp::array sub = arr.add<rjp::array>();
 	sub.add<rjp::boolean>(false);
 	sub.add<rjp::boolean>(true);
-	return rjp::cast<rjp::value&&>(arr);
+	return rjp::steal_as<rjp::value>(arr);
 }
 //handle array with subobject with subarray
 rjp::value case_18(void){
@@ -114,7 +114,7 @@ rjp::value case_18(void){
 	rjp::object subobj = arr.add<rjp::object>();
 	rjp::array subarr = subobj.add<rjp::array>("key"_ss);
 	subarr.add<rjp::boolean>(false);
-	return rjp::cast<rjp::value&&>(arr);
+	return rjp::steal_as<rjp::value>(arr);
 }
 //handle object with many members
 rjp::value case_19(void){
@@ -126,7 +126,7 @@ rjp::value case_19(void){
 		subobj.add<rjp::boolean>(rexy::static_string<char>(c), i % 2 == 0);
 		c[3] += 1;
 	}
-	return rjp::cast<rjp::value&&>(arr);
+	return rjp::steal_as<rjp::value>(arr);
 }
 //handle orderedobject with many members as array element
 /*RJP_value* case_20(void){
@@ -151,7 +151,7 @@ rjp::value case_21(void){
 	rjp::array arr = obj.add<rjp::array>("arr"_ss);
 	for(int i = 0;i < 10;++i)
 		arr.add<rjp::integer>(i);
-	return rjp::cast<rjp::value&&>(obj);
+	return rjp::steal_as<rjp::value>(obj);
 }
 /*
 //handle unorderedobject conversion
@@ -204,12 +204,12 @@ rjp::value case_27(void){
 rjp::value case_28(void){
 	rjp::object obj;
 	obj.add("key"_ss, "string"_ss);
-	return rjp::cast<rjp::value&&>(obj);
+	return rjp::steal_as<rjp::value>(obj);
 }
 rjp::value case_29(void){
 	rjp::object obj;
 	obj.add("key"_ss, ""_ss);
-	return rjp::cast<rjp::value&&>(obj);
+	return rjp::steal_as<rjp::value>(obj);
 }
 
 static test_pair tests[] = {