diff --git a/include/nana/c++defines.hpp b/include/nana/c++defines.hpp
index 1613f9b8..850113b8 100644
--- a/include/nana/c++defines.hpp
+++ b/include/nana/c++defines.hpp
@@ -36,9 +36,9 @@
  *	- STD_TO_STRING_NOT_SUPPORTED (MinGW with GCC < 4.8)
  *	- STD_FILESYSTEM_NOT_SUPPORTED (GCC < 5.3) ....
  *	- CXX_NO_INLINE_NAMESPACE (Visual C++ < 2015)
- *	- _enable_std_make_unique (__cpluscplus < 201402)
- *	- _enable_std_put_time (GCC < 5)
- *  - _enable_std_clamp (Visual C++ < 2017)
+ *	- _nana_std_make_unique (__cpluscplus < 201402)
+ *	- _nana_std_put_time (GCC < 5)
+ *  - _nana_std_clamp (Visual C++ < 2017)
   */
 
 #ifndef NANA_CXX_DEFINES_INCLUDED
@@ -145,7 +145,7 @@
 
 
 #	if ((__GNUC__ < 5)   )
-#		define _enable_std_put_time
+#		define _nana_std_put_time
 #	endif
 
 #   if ((__GNUC__ > 5) || ((__GNUC__ == 5) && (__GNUC_MINOR__ >= 3 ) ) )
@@ -189,20 +189,28 @@
 
 //Detects the feature std::make_unique
 //std::make_unique has been provided by Visual C++ 2013 and later
-#undef _enable_std_make_unique
+#undef _nana_std_make_unique
 #if (defined(__clang__) && (__cplusplus < 201305L || (__cplusplus == 201305L && (__clang_major__ * 100 + __clang_minor__ < 304 )))) \
 	|| ((!defined(__clang__)) && defined(__GNUC__) && __cplusplus < 201300L)
-#	define _enable_std_make_unique
+#	define _nana_std_make_unique
 #endif
 
 
 //Detects the feature std::clamp
 //Visual C++ 2017 with /std:c++latest provides the std::clamp
-#undef _enable_std_clamp
+#undef _nana_std_clamp
 #if (defined(_MSC_VER) && ((!defined(_MSVC_LANG)) || _MSVC_LANG < 201403L))	\
 	|| (defined(__clang__) && (__cplusplus < 201406L))						\
 	|| (defined(__GNUC__) && (!defined(__clang__)) && (__cplusplus < 201703))
-#	define _enable_std_clamp
+#	define _nana_std_clamp
+#endif
+
+
+#undef _nana_std_optional
+#if ((defined(_MSC_VER) && (_MSC_VER >= 1912) && defined(_MSVC_LANG) && _MSVC_LANG>= 201703)) ||	\
+	(defined(__clang__) && (__clang_major__ * 100 + __clang_minor__ >= 400)) ||						\
+	(!defined(__clang__) && defined(__GNUC__) && (__GNUC__ * 100 + __GNUC_MINOR__) >= 701)
+#	define _nana_std_optional
 #endif
 
 
diff --git a/include/nana/filesystem/filesystem_ext.hpp b/include/nana/filesystem/filesystem_ext.hpp
index 40eb1f60..ca579e8e 100644
--- a/include/nana/filesystem/filesystem_ext.hpp
+++ b/include/nana/filesystem/filesystem_ext.hpp
@@ -35,14 +35,14 @@ namespace filesystem_ext
 
 std::experimental::filesystem::path path_user();    ///< extention ?
 
-/// workaround Boost not having path.generic_u8string() - a good point for http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2016/p0251r0.pdf
-inline std::string generic_u8string(const std::experimental::filesystem::path& p) 
-{ 
-  #if NANA_USING_BOOST_FILESYSTEM
-	 return nana::to_utf8(p.generic_wstring());
-  #else
-	 return p.generic_u8string();
-  #endif
+													/// workaround Boost not having path.generic_u8string() - a good point for http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2016/p0251r0.pdf
+inline std::string generic_u8string(const std::experimental::filesystem::path& p)
+{
+#if NANA_USING_BOOST_FILESYSTEM
+	return nana::to_utf8(p.generic_wstring());
+#else
+	return p.generic_u8string();
+#endif
 }
 
 inline bool is_directory(const std::experimental::filesystem::directory_entry& dir) noexcept
diff --git a/include/nana/gui/detail/general_events.hpp b/include/nana/gui/detail/general_events.hpp
index 72b4cbf3..0a4881b4 100644
--- a/include/nana/gui/detail/general_events.hpp
+++ b/include/nana/gui/detail/general_events.hpp
@@ -133,11 +133,25 @@ namespace nana
 		/// Creates an event handler at the beginning of event chain
 		template<typename Function>
 		event_handle connect_front(Function && fn)
-		{	
+		{
+#ifdef __cpp_if_constexpr
+			if constexpr(std::is_invocable_v<Function, arg_reference>)
+			{
+				return _m_emplace(new docker{ this, fn, false }, true);
+			}
+			else if constexpr(std::is_invocable_v<Function>)
+			{
+				return _m_emplace(new docker{ this, [fn](arg_reference) {
+					fn();
+				}, false }, true);
+			}
+#else
 			using prototype = typename std::remove_reference<Function>::type;
 			return _m_emplace(new docker(this, factory<prototype, std::is_bind_expression<prototype>::value>::build(std::forward<Function>(fn)), false), true);
+#endif
 		}
 
+#ifndef __cpp_if_constexpr
 		/// It will not get called if stop_propagation() was called.
 		event_handle connect(void (*fn)(arg_reference))
 		{
@@ -145,13 +159,27 @@ namespace nana
 				fn(arg);
 			});
 		}
+#endif
 
 		/// It will not get called if stop_propagation() was called, because it is set at the end of the chain..
 		template<typename Function>
 		event_handle connect(Function && fn)
 		{
+#ifdef __cpp_if_constexpr
+			if constexpr(std::is_invocable_v<Function, arg_reference>)
+			{
+				return _m_emplace(new docker{ this, fn, false }, false);
+			}
+			else if constexpr(std::is_invocable_v<Function>)
+			{
+				return _m_emplace(new docker{ this, [fn](arg_reference){
+					fn();
+				}, false }, false);
+			}
+#else
 			using prototype = typename std::remove_reference<Function>::type;
 			return _m_emplace(new docker(this, factory<prototype, std::is_bind_expression<prototype>::value>::build(std::forward<Function>(fn)), false), false);
+#endif
 		}
 
 		/// It will not get called if stop_propagation() was called.
@@ -164,10 +192,22 @@ namespace nana
 		/// It will get called because it is unignorable.
         template<typename Function>
 		event_handle connect_unignorable(Function && fn, bool in_front = false)
-		{			
+		{
+#ifdef __cpp_if_constexpr
+			if constexpr(std::is_invocable_v<Function, arg_reference>)
+			{
+				return _m_emplace(new docker{ this, fn, true }, in_front);
+			}
+			else if constexpr(std::is_invocable_v<Function>)
+			{
+				return _m_emplace(new docker{ this, [fn](arg_reference) {
+					fn();
+				}, true }, in_front);
+			}
+#else
 			using prototype = typename std::remove_reference<Function>::type;
-
 			return _m_emplace(new docker(this, factory<prototype, std::is_bind_expression<prototype>::value>::build(std::forward<Function>(fn)), true), in_front);
+#endif
 		}
 
 		void emit(arg_reference& arg, window window_handle)
@@ -210,6 +250,8 @@ namespace nana
 			}
 		}
 	private:
+
+#ifndef __cpp_if_constexpr
 		template<typename Fn, bool IsBind>
 		struct factory
 		{
@@ -385,6 +427,7 @@ namespace nana
 				};
 			}
 		};
+#endif
 	};
  
 	struct arg_mouse
diff --git a/include/nana/gui/detail/widget_content_measurer_interface.hpp b/include/nana/gui/detail/widget_content_measurer_interface.hpp
index 4f175493..ca0f5a55 100644
--- a/include/nana/gui/detail/widget_content_measurer_interface.hpp
+++ b/include/nana/gui/detail/widget_content_measurer_interface.hpp
@@ -35,7 +35,7 @@ namespace nana
 			 * @param limit_width True if limits the width, false if limits the height.
 			 * @return the size of content.
 			 */
-			virtual optional<size> measure(graph_reference graph, unsigned limit_pixels, bool limit_width) const = 0;
+			virtual ::std::optional<size> measure(graph_reference graph, unsigned limit_pixels, bool limit_width) const = 0;
 
 			/// Returns the extension to the size of widget from content extent
 			/**
diff --git a/include/nana/gui/msgbox.hpp b/include/nana/gui/msgbox.hpp
index 67840f1a..02b4fe35 100644
--- a/include/nana/gui/msgbox.hpp
+++ b/include/nana/gui/msgbox.hpp
@@ -240,7 +240,11 @@ namespace nana
 		bool show(Args&& ... args)
 		{
 			std::vector<abstract_content*> contents;
+#ifdef __cpp_fold_expressions
+			(contents.emplace_back(&args), ...);
+#else
 			_m_fetch_args(contents, std::forward<Args>(args)...);
+#endif
 			if (contents.empty())
 				return false;
 
@@ -270,6 +274,7 @@ namespace nana
 		void min_width_entry_field( unsigned pixels );
 
 	private:
+#ifndef __cpp_fold_expressions
 		void _m_fetch_args(std::vector<abstract_content*>&);
 
 		template<typename ...Args>
@@ -278,6 +283,7 @@ namespace nana
 			contents.push_back(&content);
 			_m_fetch_args(contents, std::forward<Args>(args)...);
 		}
+#endif
 
 		bool _m_open(std::vector<abstract_content*>&, bool modal);
 	private:
diff --git a/include/nana/gui/programming_interface.hpp b/include/nana/gui/programming_interface.hpp
index 7d7e0538..134b0082 100644
--- a/include/nana/gui/programming_interface.hpp
+++ b/include/nana/gui/programming_interface.hpp
@@ -89,7 +89,7 @@ namespace API
 		void set_measurer(window, ::nana::dev::widget_content_measurer_interface*);
 
 		void attach_drawer(widget&, drawer_trigger&);
-		::nana::detail::native_string_type window_caption(window) throw();
+		::nana::detail::native_string_type window_caption(window) noexcept;
 		void window_caption(window, ::nana::detail::native_string_type);
 
 		window create_window(window, bool nested, const rectangle&, const appearance&, widget* attached);
@@ -255,6 +255,19 @@ namespace API
 		if (nullptr == general_evt)
 			throw std::invalid_argument("API::events(): bad parameter window handle, no events object or invalid window handle.");
 
+#ifdef __cpp_if_constexpr
+		if constexpr(std::is_same_v<event_type, ::nana::general_events>)
+		{
+			return *general_evt;
+		}
+		else
+		{
+			auto * widget_evt = dynamic_cast<event_type*>(general_evt);
+			if (nullptr == widget_evt)
+				throw std::invalid_argument("API::events(): bad template parameter Widget, the widget type and window handle do not match.");
+			return *widget_evt;
+		}
+#else
 		if (std::is_same<::nana::general_events, event_type>::value)
 			return *static_cast<event_type*>(general_evt);
 
@@ -262,6 +275,7 @@ namespace API
 		if (nullptr == widget_evt)
 			throw std::invalid_argument("API::events(): bad template parameter Widget, the widget type and window handle do not match.");
 		return *widget_evt;
+#endif
 	}
 
 	template<typename EventArg, typename std::enable_if<std::is_base_of< ::nana::event_arg, EventArg>::value>::type* = nullptr>
@@ -288,6 +302,19 @@ namespace API
 		if (nullptr == wdg_colors)
 			throw std::invalid_argument("API::scheme(): bad parameter window handle, no events object or invalid window handle.");
 
+#ifdef __cpp_if_constexpr
+		if constexpr(std::is_same<::nana::widget_geometrics, scheme_type>::value)
+		{
+			return *static_cast<scheme_type*>(wdg_colors);
+		}
+		else
+		{
+			auto * comp_wdg_colors = dynamic_cast<scheme_type*>(wdg_colors);
+			if (nullptr == comp_wdg_colors)
+				throw std::invalid_argument("API::scheme(): bad template parameter Widget, the widget type and window handle do not match.");
+			return *comp_wdg_colors;
+		}
+#else
 		if (std::is_same<::nana::widget_geometrics, scheme_type>::value)
 			return *static_cast<scheme_type*>(wdg_colors);
 
@@ -295,6 +322,7 @@ namespace API
 		if (nullptr == comp_wdg_colors)
 			throw std::invalid_argument("API::scheme(): bad template parameter Widget, the widget type and window handle do not match.");
 		return *comp_wdg_colors;
+#endif
 	}
 
 	point window_position(window);
@@ -312,7 +340,7 @@ namespace API
 	size window_outline_size(window);
 	void window_outline_size(window, const size&);
 
-	nana::optional<rectangle> window_rectangle(window);
+	::std::optional<rectangle> window_rectangle(window);
 	bool get_window_rectangle(window, rectangle&);
 	bool track_window_size(window, const size&, bool true_for_max);   ///< Sets the minimum or maximum tracking size of a window.
 	void window_enabled(window, bool);
@@ -434,7 +462,7 @@ namespace API
 	bool ignore_mouse_focus(window, bool ignore);	///< Enables/disables the mouse focus, it returns the previous state
 	bool ignore_mouse_focus(window);				///< Determines whether the mouse focus is enabled
 
-	void at_safe_place(window, std::function<void()>);
+	void at_safe_place(window, ::std::function<void()>);
 
 	/// Returns a widget content extent size
 	/**
@@ -445,7 +473,7 @@ namespace API
 	 * @return if optional has a value, the first size indicates the content extent, the second size indicates the size of
 	 * widget by the content extent. 
 	 */
-	optional<std::pair<::nana::size, ::nana::size>> content_extent(window wd, unsigned limited_px, bool limit_width);
+	::std::optional<std::pair<::nana::size, ::nana::size>> content_extent(window wd, unsigned limited_px, bool limit_width);
 
 	unsigned screen_dpi(bool x_requested);
 }//end namespace API
diff --git a/include/nana/gui/widgets/combox.hpp b/include/nana/gui/widgets/combox.hpp
index fc8e4522..551c65d3 100644
--- a/include/nana/gui/widgets/combox.hpp
+++ b/include/nana/gui/widgets/combox.hpp
@@ -223,7 +223,7 @@ namespace nana
 		const drawerbase::combox::drawer_impl& _m_impl() const;
 	private:
 		//Overrides widget's virtual functions
-		native_string_type _m_caption() const throw() override;
+		native_string_type _m_caption() const noexcept override;
 		void _m_caption(native_string_type&&) override;
 		nana::any * _m_anyobj(std::size_t pos, bool alloc_if_empty) const override;
 	};
diff --git a/include/nana/gui/widgets/detail/widget_iterator.hpp b/include/nana/gui/widgets/detail/widget_iterator.hpp
new file mode 100644
index 00000000..c78e5d4d
--- /dev/null
+++ b/include/nana/gui/widgets/detail/widget_iterator.hpp
@@ -0,0 +1,36 @@
+/*
+ *	A Widget Iterator Template
+ *	Copyright(C) 2017 Jinhao(cnjinhao@hotmail.com)
+ *
+ *	Distributed under the Boost Software License, Version 1.0.
+ *	(See accompanying file LICENSE_1_0.txt or copy at
+ *	http://www.boost.org/LICENSE_1_0.txt)
+ *
+ *	@file: nana/gui/widgets/detail/widget_iterator.hpp
+ *  @description: widget_iterator is the base class provided to simplify definitions of the required types for widget iterators.
+ *	It is provided because of deprecation of std::iterator in C++17
+ */
+#ifndef NANA_GUI_WIDGET_ITERATOR_INCLUDED
+#define NANA_GUI_WIDGET_ITERATOR_INCLUDED
+
+#include <cstddef>	//provides std::ptrdiff_t
+
+
+namespace nana {
+	namespace widgets {
+		namespace detail
+		{
+			template<typename Category, typename T>
+			class widget_iterator
+			{
+				using iterator_category = Category;
+				using value_type = T;
+				using difference_type = std::ptrdiff_t;
+				using pointer = T * ;
+				using reference = T & ;
+			};
+		}
+	}
+}
+
+#endif
diff --git a/include/nana/gui/widgets/group.hpp b/include/nana/gui/widgets/group.hpp
index 6ec70c0a..86ca663b 100644
--- a/include/nana/gui/widgets/group.hpp
+++ b/include/nana/gui/widgets/group.hpp
@@ -83,7 +83,7 @@ namespace nana{
 		void _m_add_child(const char* field, widget*);
 		void _m_init();
 		void _m_complete_creation() override;
-		native_string_type _m_caption() const throw() override;
+		native_string_type _m_caption() const noexcept override;
 		void _m_caption(native_string_type&&) override;
 	private:
 		std::unique_ptr<implement> impl_;
diff --git a/include/nana/gui/widgets/label.hpp b/include/nana/gui/widgets/label.hpp
index ee26383b..09d990e4 100644
--- a/include/nana/gui/widgets/label.hpp
+++ b/include/nana/gui/widgets/label.hpp
@@ -62,12 +62,12 @@ namespace nana
 		label(window parent, const char* text, bool visible = true) :label(parent, std::string(text),visible) {};
 		label(window, const rectangle& = {}, bool visible = true);
 		label& transparent(bool);		///< Switchs the label widget to the transparent background mode.
-		bool transparent() const throw();
+		bool transparent() const noexcept;
 		label& format(bool);		///< Switches the format mode of the widget.
 		label& add_format_listener(std::function<void(command, const std::string&)>);
 
 		/// as same as the HTML "for" attribute of a label
-		label& click_for(window associated_window) throw();
+		label& click_for(window associated_window) noexcept;
 
 		/// Returns the size of the text. If *allowed_width_in_pixel* is not zero, returns a 
 		/// "corrected" size that changes lines to fit the text into the specified width
diff --git a/include/nana/gui/widgets/listbox.hpp b/include/nana/gui/widgets/listbox.hpp
index 36a38f65..21f20856 100644
--- a/include/nana/gui/widgets/listbox.hpp
+++ b/include/nana/gui/widgets/listbox.hpp
@@ -23,6 +23,7 @@
 
 #include "widget.hpp"
 #include "detail/inline_widget.hpp"
+#include "detail/widget_iterator.hpp"
 #include <nana/pat/abstract_factory.hpp>
 #include <nana/concepts.hpp>
 #include <nana/key_type.hpp>
@@ -808,7 +809,8 @@ namespace nana
 			/// operate with absolute positions and contain only the position but montain pointers to parts of the real items 
 			/// item_proxy self, it references and iterators are not invalidated by sort()
 			class item_proxy
-				: public std::iterator<std::input_iterator_tag, item_proxy>
+				//: public std::iterator<std::input_iterator_tag, item_proxy>	//deprecated
+				: public ::nana::widgets::detail::widget_iterator<std::input_iterator_tag, item_proxy>
 			{
 			public:
 				item_proxy(essence*, const index_pair& = index_pair{npos, npos});
@@ -982,7 +984,8 @@ namespace nana
 			};
 
 			class cat_proxy
-				: public std::iterator < std::input_iterator_tag, cat_proxy >
+				//: public std::iterator<std::input_iterator_tag, cat_proxy>	//deprecated
+				: public ::nana::widgets::detail::widget_iterator<std::input_iterator_tag, cat_proxy>
 			{
 			public:
 				using inline_notifier_interface = drawerbase::listbox::inline_notifier_interface;
diff --git a/include/nana/gui/widgets/spinbox.hpp b/include/nana/gui/widgets/spinbox.hpp
index 542874f7..9595321f 100644
--- a/include/nana/gui/widgets/spinbox.hpp
+++ b/include/nana/gui/widgets/spinbox.hpp
@@ -116,7 +116,7 @@ namespace nana
 		void modifier(std::string prefix_utf8, std::string suffix_utf8);
 		void modifier(const std::wstring & prefix, const std::wstring& suffix);
 	private:
-		native_string_type _m_caption() const throw();
+		native_string_type _m_caption() const noexcept;
 		void _m_caption(native_string_type&&);
 	}; //end class spinbox
 }//end namespace nana
diff --git a/include/nana/gui/widgets/tabbar.hpp b/include/nana/gui/widgets/tabbar.hpp
index a24cce4a..17a57411 100644
--- a/include/nana/gui/widgets/tabbar.hpp
+++ b/include/nana/gui/widgets/tabbar.hpp
@@ -383,7 +383,7 @@ namespace nana
 					driver();
 					~driver();
 
-					model* get_model() const throw();
+					model* get_model() const noexcept;
 				private:
 					//Overrides drawer_trigger's method
 					void attached(widget_reference, graph_reference)	override;
diff --git a/include/nana/gui/widgets/textbox.hpp b/include/nana/gui/widgets/textbox.hpp
index 4a2663ae..c46aa1ca 100644
--- a/include/nana/gui/widgets/textbox.hpp
+++ b/include/nana/gui/widgets/textbox.hpp
@@ -276,7 +276,7 @@ namespace nana
 		std::size_t text_line_count() const noexcept;
 	protected:
 		//Overrides widget's virtual functions
-		native_string_type _m_caption() const throw() override;
+		native_string_type _m_caption() const noexcept override;
 		void _m_caption(native_string_type&&) override;
 		void _m_typeface(const paint::font&) override;
 		std::shared_ptr<scroll_operation_interface> _m_scroll_operation() override;
diff --git a/include/nana/gui/widgets/widget.hpp b/include/nana/gui/widgets/widget.hpp
index 10a3e352..d7be3acf 100644
--- a/include/nana/gui/widgets/widget.hpp
+++ b/include/nana/gui/widgets/widget.hpp
@@ -54,9 +54,9 @@ namespace nana
 
 		window parent() const;
 
-		::std::string caption() const throw();
-		::std::wstring caption_wstring() const throw();
-		native_string_type caption_native() const throw();
+		::std::string caption() const noexcept;
+		::std::wstring caption_wstring() const noexcept;
+		native_string_type caption_native() const noexcept;
 
 		widget& caption(std::string utf8);
 		widget& caption(std::wstring);
@@ -132,7 +132,7 @@ namespace nana
 		virtual void _m_complete_creation();
 
 		virtual general_events& _m_get_general_events() const = 0;
-		virtual native_string_type _m_caption() const throw();
+		virtual native_string_type _m_caption() const noexcept;
 		virtual void _m_caption(native_string_type&&);
 		virtual nana::cursor _m_cursor() const;
 		virtual void _m_cursor(nana::cursor);
diff --git a/include/nana/internationalization.hpp b/include/nana/internationalization.hpp
index 4b3e3918..cab02568 100644
--- a/include/nana/internationalization.hpp
+++ b/include/nana/internationalization.hpp
@@ -34,7 +34,12 @@ namespace nana
 		::std::string get(std::string msgid_utf8, Args&&... args) const
 		{
 			std::vector<std::string> arg_strs;
+
+#ifdef __cpp_fold_expressions
+			(_m_fetch_args(arg_strs, std::forward<Args>(args)),...);
+#else
 			_m_fetch_args(arg_strs, std::forward<Args>(args)...);
+#endif
 			
 			auto msgstr = _m_get(std::move(msgid_utf8));
 			_m_replace_args(msgstr, &arg_strs);
@@ -53,25 +58,28 @@ namespace nana
 		std::string _m_get(std::string&& msgid) const;
 		void _m_replace_args(::std::string& str, std::vector<::std::string> * arg_strs) const;
 
-		void _m_fetch_args(std::vector<std::string>&) const; //Termination of _m_fetch_args
+#ifndef __cpp_fold_expressions
+		static void _m_fetch_args(std::vector<std::string>&); //Termination of _m_fetch_args
+#endif
 
-		void _m_fetch_args(std::vector<std::string>& v, const char* arg) const;
-		void _m_fetch_args(std::vector<std::string>& v, const std::string& arg) const;
-		void _m_fetch_args(std::vector<std::string>& v, std::string& arg) const;
-		void _m_fetch_args(std::vector<std::string>& v, std::string&& arg) const;
-		void _m_fetch_args(std::vector<std::string>& v, const wchar_t* arg) const;
-		void _m_fetch_args(std::vector<std::string>& v, const std::wstring& arg) const;
-		void _m_fetch_args(std::vector<std::string>& v, std::wstring& arg) const;
-		void _m_fetch_args(std::vector<std::string>& v, std::wstring&& arg) const;
+		static void _m_fetch_args(std::vector<std::string>& v, const char* arg);
+		static void _m_fetch_args(std::vector<std::string>& v, const std::string& arg);
+		static void _m_fetch_args(std::vector<std::string>& v, std::string& arg);
+		static void _m_fetch_args(std::vector<std::string>& v, std::string&& arg);
+		static void _m_fetch_args(std::vector<std::string>& v, const wchar_t* arg);
+		static void _m_fetch_args(std::vector<std::string>& v, const std::wstring& arg);
+		static void _m_fetch_args(std::vector<std::string>& v, std::wstring& arg);
+		static void _m_fetch_args(std::vector<std::string>& v, std::wstring&& arg);
 
 		template<typename Arg>
-		void _m_fetch_args(std::vector<std::string>& v, Arg&& arg) const
+		static void _m_fetch_args(std::vector<std::string>& v, Arg&& arg)
 		{
 			std::stringstream ss;
 			ss << arg;
 			v.emplace_back(ss.str());
 		}
 
+#ifndef __cpp_fold_expressions
 		template<typename ...Args>
 		void _m_fetch_args(std::vector<std::string>& v, const char* arg, Args&&... args) const
 		{
@@ -136,6 +144,7 @@ namespace nana
 			v.emplace_back(ss.str());
 			_m_fetch_args(v, std::forward<Args>(args)...);
 		}
+#endif
 	};//end class internationalization
 
 	class i18n_eval
@@ -180,7 +189,11 @@ namespace nana
 		i18n_eval(std::string msgid_utf8, Args&&... args)
 			: msgid_(std::move(msgid_utf8))
 		{
+#ifdef __cpp_fold_expressions
+			(_m_fetch_args(std::forward<Args>(args)), ...);
+#else
 			_m_fetch_args(std::forward<Args>(args)...);
+#endif
 		}
 
 		i18n_eval(const i18n_eval&);
@@ -193,6 +206,7 @@ namespace nana
 
 		std::string operator()() const;
 	private:
+#ifndef __cpp_fold_expressions
 		void _m_fetch_args(){}	//Termination of _m_fetch_args
 
 		template<typename Arg, typename ...Args>
@@ -201,6 +215,7 @@ namespace nana
 			_m_add_args(std::forward<Arg>(arg));
 			_m_fetch_args(std::forward<Args>(args)...);
 		}
+#endif
 
 		template<typename Arg>
 		void _m_add_args(Arg&& arg)
diff --git a/include/nana/optional.hpp b/include/nana/optional.hpp
index 49b81d88..1bb8373b 100644
--- a/include/nana/optional.hpp
+++ b/include/nana/optional.hpp
@@ -15,8 +15,13 @@
 #ifndef NANA_STD_OPTIONAL_HEADER_INCLUDED
 #define NANA_STD_OPTIONAL_HEADER_INCLUDED
 
-#include <stdexcept>
 #include <nana/c++defines.hpp>
+
+#ifdef _nana_std_optional
+#include <optional>
+#else
+#include <stdexcept>
+
 namespace nana
 {
 	namespace detail
@@ -361,4 +366,10 @@ namespace nana
 	};
 }
 
+namespace std
+{
+	using nana::optional;
+}
+
+#endif	//_nana_std_optional
 #endif
diff --git a/include/nana/paint/graphics.hpp b/include/nana/paint/graphics.hpp
index ad0ef379..f3b33aa5 100644
--- a/include/nana/paint/graphics.hpp
+++ b/include/nana/paint/graphics.hpp
@@ -156,7 +156,7 @@ namespace nana
 
 			/// Saves images as a windows bitmap file
 			/// @param file_utf8 A UTF-8 string to a filename
-			void save_as_file(const char* file_utf8) const throw();
+			void save_as_file(const char* file_utf8) const noexcept;
 
 			::nana::color	palette(bool for_text) const;
 			graphics&		palette(bool for_text, const ::nana::color&);
diff --git a/include/nana/stdc++.hpp b/include/nana/stdc++.hpp
index c21d8a94..54d62f73 100644
--- a/include/nana/stdc++.hpp
+++ b/include/nana/stdc++.hpp
@@ -86,7 +86,7 @@ namespace std
 }
 #endif
 
-#ifdef _enable_std_make_unique
+#ifdef _nana_std_make_unique
 	// http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2013/n3656.htm
 
 #include <cstddef>
@@ -124,9 +124,9 @@ namespace std {
 	typename _Unique_if<T>::_Known_bound
 		make_unique(Args&&...) = delete;
 }
-#endif //_enable_std_make_unique
+#endif //_nana_std_make_unique
 
-#ifdef _enable_std_put_time
+#ifdef _nana_std_put_time
 #include <ctime>
 #include <string>
 namespace std
@@ -144,9 +144,9 @@ namespace std
 	//template<>
 	//std::wstring put_time<wchar_t, std::wstring>(const std::tm* tmb, const wchar_t* fmt);
 }
-#endif  // _enable_std_put_time
+#endif  // _nana_std_put_time
 
-#if defined(_enable_std_clamp)
+#if defined(_nana_std_clamp)
 namespace std
 {
 	//<algorithm> since C++17
diff --git a/include/nana/verbose_preprocessor.hpp b/include/nana/verbose_preprocessor.hpp
index b4804546..7f1d037c 100644
--- a/include/nana/verbose_preprocessor.hpp
+++ b/include/nana/verbose_preprocessor.hpp
@@ -80,7 +80,7 @@
 	#pragma message (  SHOW_VALUE(USE_github_com_meganz_mingw_std_threads)  )
 	#pragma message (  SHOW_VALUE(NANA_ENABLE_MINGW_STD_THREADS_WITH_MEGANZ)  )
 	#pragma message (  SHOW_VALUE(STD_THREAD_NOT_SUPPORTED)  )
-	#pragma message (  SHOW_VALUE(_enable_std_put_time)  )
+	#pragma message (  SHOW_VALUE(_nana_std_put_time)  )
 	#pragma message (  SHOW_VALUE(STD_MAKE_UNIQUE_NOT_SUPPORTED)  )
 
 	#pragma message (  SHOW_VALUE(STD_FILESYSTEM_NOT_SUPPORTED)  )
diff --git a/source/filesystem/filesystem.cpp b/source/filesystem/filesystem.cpp
index 5bac5a40..ee636f18 100644
--- a/source/filesystem/filesystem.cpp
+++ b/source/filesystem/filesystem.cpp
@@ -16,7 +16,7 @@
 #include <sstream>
 
 #include <nana/config.hpp>
-#ifdef _enable_std_put_time
+#ifdef _nana_std_put_time
 	#include <nana/stdc++.hpp>
 #else
 	#include <iomanip>
diff --git a/source/gui/msgbox.cpp b/source/gui/msgbox.cpp
index 75ce6a23..36a7c202 100644
--- a/source/gui/msgbox.cpp
+++ b/source/gui/msgbox.cpp
@@ -1294,8 +1294,10 @@ namespace nana
         min_width_entry_field_pixels_ = pixels;
 	}
 
+#ifndef _nana_cxx_folding_expression
 	void inputbox::_m_fetch_args(std::vector<abstract_content*>&)
 	{}
+#endif
 
 	bool inputbox::_m_open(std::vector<abstract_content*>& contents, bool modal)
 	{
diff --git a/source/gui/programming_interface.cpp b/source/gui/programming_interface.cpp
index da45698b..ed81cef7 100644
--- a/source/gui/programming_interface.cpp
+++ b/source/gui/programming_interface.cpp
@@ -260,7 +260,7 @@ namespace API
 			}
 		}
 
-		::nana::detail::native_string_type window_caption(window wd) throw()
+		::nana::detail::native_string_type window_caption(window wd) noexcept
 		{
 			auto const iwd = reinterpret_cast<basic_window*>(wd);
 			internal_scope_guard isg;
@@ -838,7 +838,7 @@ namespace API
 		}
 	}
 
-	nana::optional<rectangle> window_rectangle(window wd)
+	std::optional<rectangle> window_rectangle(window wd)
 	{
 		auto iwd = reinterpret_cast<basic_window*>(wd);
 		internal_scope_guard lock;
@@ -1476,7 +1476,7 @@ namespace API
 		restrict::wd_manager().set_safe_place(reinterpret_cast<basic_window*>(wd), std::move(fn));
 	}
 
-	optional<std::pair<size, size>> content_extent(window wd, unsigned limited_px, bool limit_width)
+	std::optional<std::pair<size, size>> content_extent(window wd, unsigned limited_px, bool limit_width)
 	{
 		auto iwd = reinterpret_cast<basic_window*>(wd);
 		internal_scope_guard lock;
diff --git a/source/gui/widgets/button.cpp b/source/gui/widgets/button.cpp
index fe6f19c7..b7d3214b 100644
--- a/source/gui/widgets/button.cpp
+++ b/source/gui/widgets/button.cpp
@@ -27,7 +27,7 @@ namespace nana{	namespace drawerbase
 				: trigger_{ t }
 			{}
 
-			optional<size> measure(graph_reference graph, unsigned limit_pixels, bool /*limit_width*/) const override
+			std::optional<size> measure(graph_reference graph, unsigned limit_pixels, bool /*limit_width*/) const override
 			{
 				//Button doesn't provide a support of vfit and hfit
 				if (limit_pixels)
diff --git a/source/gui/widgets/combox.cpp b/source/gui/widgets/combox.cpp
index c9b6311d..dcaf5c43 100644
--- a/source/gui/widgets/combox.cpp
+++ b/source/gui/widgets/combox.cpp
@@ -90,7 +90,7 @@ namespace nana
 						: drw_{ drwimpl }
 					{}
 
-					optional<size> measure(graph_reference graph, unsigned limit_pixels, bool /*limit_width*/) const override
+					std::optional<size> measure(graph_reference graph, unsigned limit_pixels, bool /*limit_width*/) const override
 					{
 						//Combox doesn't provide a support of vfit and hfit
 						if (limit_pixels)
@@ -1037,7 +1037,7 @@ namespace nana
 				API::refresh_window(*this);
 		}
 
-		auto combox::_m_caption() const throw() -> native_string_type
+		auto combox::_m_caption() const noexcept -> native_string_type
 		{
 			internal_scope_guard lock;
 			auto editor = _m_impl().editor();
diff --git a/source/gui/widgets/group.cpp b/source/gui/widgets/group.cpp
index b3c2658d..23cc287c 100644
--- a/source/gui/widgets/group.cpp
+++ b/source/gui/widgets/group.cpp
@@ -271,7 +271,7 @@ namespace nana{
 		_m_init();
 	}
 
-	auto group::_m_caption() const throw() -> native_string_type
+	auto group::_m_caption() const noexcept -> native_string_type
 	{
 		return impl_->caption.caption_native();
 	}
diff --git a/source/gui/widgets/label.cpp b/source/gui/widgets/label.cpp
index 1d436f68..bf670c12 100644
--- a/source/gui/widgets/label.cpp
+++ b/source/gui/widgets/label.cpp
@@ -653,7 +653,7 @@ namespace nana
 						: impl_{ impl }
 					{}
 
-					optional<size> measure(graph_reference graph, unsigned limit_pixels, bool limit_width) const override
+					std::optional<size> measure(graph_reference graph, unsigned limit_pixels, bool limit_width) const override
 					{
 						//Label now doesn't support to measure content with a specified height.
 						if (graph && ((0 == limit_pixels) || limit_width))
@@ -825,7 +825,7 @@ namespace nana
 			return *this;
 		}
 
-		bool label::transparent() const throw()
+		bool label::transparent() const noexcept
 		{
 			return API::is_transparent_background(*this);
 		}
@@ -849,7 +849,7 @@ namespace nana
 			return *this;
 		}
 
-		label& label::click_for(window associated_window) throw()
+		label& label::click_for(window associated_window) noexcept
 		{
 			get_drawer_trigger().impl()->for_associated_wd = associated_window;
 			return *this;
diff --git a/source/gui/widgets/picture.cpp b/source/gui/widgets/picture.cpp
index 356072b9..cba8a75c 100644
--- a/source/gui/widgets/picture.cpp
+++ b/source/gui/widgets/picture.cpp
@@ -74,7 +74,7 @@ namespace nana
 					: impl_{impl}
 				{}
 
-				optional<size> measure(graph_reference /*graph*/, unsigned limit_pixels, bool /*limit_width*/) const override
+				std::optional<size> measure(graph_reference /*graph*/, unsigned limit_pixels, bool /*limit_width*/) const override
 				{
 					//Picture doesn't provide a support of vfit and hfit
 					if (!limit_pixels)
diff --git a/source/gui/widgets/spinbox.cpp b/source/gui/widgets/spinbox.cpp
index af1288eb..6ed1f3ed 100644
--- a/source/gui/widgets/spinbox.cpp
+++ b/source/gui/widgets/spinbox.cpp
@@ -82,10 +82,39 @@ namespace nana
 
 				bool check_value(const std::string& str) const override
 				{
+#ifdef __cpp_if_constexpr
+					auto i = str.c_str();
+					if ('+' == *i || '-' == *i)
+						++i;
+
+					if constexpr(std::is_same<T, int>::value)
+					{
+						for (; 0 != *i; ++i)
+						{
+							if (*i < '0' || '9' < *i)
+								return false;
+						}
+					}
+					else
+					{
+						bool dot = false;
+						for (; 0 != *i; ++i)
+						{
+							if (('.' == *i) && (!dot))
+							{
+								dot = true;
+								continue;
+							}
+
+							if (*i < '0' || '9' < *i)
+								return false;
+						}
+					}
+#else
 					if (str.empty())
 						return true;
 
-					auto size = str.size();
+					auto const size = str.size();
 					std::size_t pos = 0;
 					if (str[0] == '+' || str[0] == '-')
 						pos = 1;
@@ -115,6 +144,7 @@ namespace nana
 								return false;
 						}
 					}
+#endif
 					return true;
 				}
 
@@ -744,7 +774,7 @@ namespace nana
 		modifier(to_utf8(prefix), to_utf8(suffix));
 	}
 
-	auto spinbox::_m_caption() const throw() -> native_string_type
+	auto spinbox::_m_caption() const noexcept -> native_string_type
 	{
 		internal_scope_guard lock;
 		auto editor = get_drawer_trigger().impl()->editor();
diff --git a/source/gui/widgets/tabbar.cpp b/source/gui/widgets/tabbar.cpp
index ad614c09..2337f468 100644
--- a/source/gui/widgets/tabbar.cpp
+++ b/source/gui/widgets/tabbar.cpp
@@ -1533,7 +1533,7 @@ namespace nana
 						delete model_;
 					}
 
-					model* driver::get_model() const throw()
+					model* driver::get_model() const noexcept
 					{
 						return model_;
 					}
diff --git a/source/gui/widgets/textbox.cpp b/source/gui/widgets/textbox.cpp
index 2fbc9290..db57ae82 100644
--- a/source/gui/widgets/textbox.cpp
+++ b/source/gui/widgets/textbox.cpp
@@ -785,7 +785,7 @@ namespace drawerbase {
 		}
 
 		//Override _m_caption for caption()
-		auto textbox::_m_caption() const throw() -> native_string_type
+		auto textbox::_m_caption() const noexcept -> native_string_type
 		{
 			internal_scope_guard lock;
 			auto editor = get_drawer_trigger().editor();
diff --git a/source/gui/widgets/widget.cpp b/source/gui/widgets/widget.cpp
index 3e3ab2cd..baf31f76 100644
--- a/source/gui/widgets/widget.cpp
+++ b/source/gui/widgets/widget.cpp
@@ -54,12 +54,12 @@ namespace nana
 			widget& wdg_;
 		};
 
-		std::string widget::caption() const throw()
+		std::string widget::caption() const noexcept
 		{
 			return to_utf8(_m_caption());
 		}
 
-		std::wstring widget::caption_wstring() const throw()
+		std::wstring widget::caption_wstring() const noexcept
 		{
 #if defined(NANA_WINDOWS)
 			return _m_caption();
@@ -68,7 +68,7 @@ namespace nana
 #endif
 		}
 
-		auto widget::caption_native() const throw() -> native_string_type
+		auto widget::caption_native() const noexcept -> native_string_type
 		{
 			return _m_caption();
 		}
@@ -287,7 +287,7 @@ namespace nana
 		void widget::_m_complete_creation()
 		{}
 
-		auto widget::_m_caption() const throw() -> native_string_type
+		auto widget::_m_caption() const noexcept -> native_string_type
 		{
 			return API::dev::window_caption(handle());
 		}
diff --git a/source/internationalization.cpp b/source/internationalization.cpp
index 87c92437..4252d73c 100644
--- a/source/internationalization.cpp
+++ b/source/internationalization.cpp
@@ -414,45 +414,47 @@ namespace nana
 		}
 	}
 
-	void internationalization::_m_fetch_args(std::vector<std::string>&) const
+#ifndef _nana_cxx_folding_expression
+	void internationalization::_m_fetch_args(std::vector<std::string>&)
 	{}
+#endif
 	
-	void internationalization::_m_fetch_args(std::vector<std::string>& v, const char* arg) const
+	void internationalization::_m_fetch_args(std::vector<std::string>& v, const char* arg)
 	{
 		v.emplace_back(arg);
 	}
 
-	void internationalization::_m_fetch_args(std::vector<std::string>& v, const std::string& arg) const
+	void internationalization::_m_fetch_args(std::vector<std::string>& v, const std::string& arg)
 	{
 		v.emplace_back(arg);
 	}
 
-	void internationalization::_m_fetch_args(std::vector<std::string>& v, std::string& arg) const
+	void internationalization::_m_fetch_args(std::vector<std::string>& v, std::string& arg)
 	{
 		v.emplace_back(arg);
 	}
 
-	void internationalization::_m_fetch_args(std::vector<std::string>& v, std::string&& arg) const
+	void internationalization::_m_fetch_args(std::vector<std::string>& v, std::string&& arg)
 	{
 		v.emplace_back(std::move(arg));
 	}
 
-	void internationalization::_m_fetch_args(std::vector<std::string>& v, const wchar_t* arg) const
+	void internationalization::_m_fetch_args(std::vector<std::string>& v, const wchar_t* arg)
 	{
 		v.emplace_back(to_utf8(arg));
 	}
 
-	void internationalization::_m_fetch_args(std::vector<std::string>& v, const std::wstring& arg) const
+	void internationalization::_m_fetch_args(std::vector<std::string>& v, const std::wstring& arg)
 	{
 		v.emplace_back(to_utf8(arg));
 	}
 
-	void internationalization::_m_fetch_args(std::vector<std::string>& v, std::wstring& arg) const
+	void internationalization::_m_fetch_args(std::vector<std::string>& v, std::wstring& arg)
 	{
 		v.emplace_back(to_utf8(arg));
 	}
 
-	void internationalization::_m_fetch_args(std::vector<std::string>& v, std::wstring&& arg) const
+	void internationalization::_m_fetch_args(std::vector<std::string>& v, std::wstring&& arg)
 	{
 		v.emplace_back(to_utf8(arg));
 	}
diff --git a/source/paint/graphics.cpp b/source/paint/graphics.cpp
index c021485d..2d92b435 100644
--- a/source/paint/graphics.cpp
+++ b/source/paint/graphics.cpp
@@ -937,7 +937,7 @@ namespace paint
 			impl_->size.width = impl_->size.height = 0;
 		}
 
-		void graphics::save_as_file(const char* file_utf8) const throw()
+		void graphics::save_as_file(const char* file_utf8) const noexcept
 		{
 			if(impl_->handle)
 			{
diff --git a/source/stdc++.cpp b/source/stdc++.cpp
index 593ec334..2d2167ee 100644
--- a/source/stdc++.cpp
+++ b/source/stdc++.cpp
@@ -426,7 +426,7 @@ namespace std
 }
 #endif
 
-#ifdef _enable_std_put_time
+#ifdef _nana_std_put_time
 #include <cwchar>
 namespace std
 {