More if constexpr work

include/chaiscript/dispatchkit/bootstrap.hpp

@@ -112,29 +112,18 @@ namespace chaiscript
     /// uses ostream operator >> to perform the conversion
     template<typename Input>
     auto parse_string(const std::string &i)
-      -> typename std::enable_if<
-             !std::is_same<Input, wchar_t>::value
-             && !std::is_same<Input, char16_t>::value
-             && !std::is_same<Input, char32_t>::value,
-      Input>::type
     {
+      if constexpr (!std::is_same<Input, wchar_t>::value
+          && !std::is_same<Input, char16_t>::value
+          && !std::is_same<Input, char32_t>::value) {
         std::stringstream ss(i);
         Input t;
         ss >> t;
         return t;
-    }
+      } else {
-
-    template<typename Input>
-    auto parse_string(const std::string &) 
-      -> typename std::enable_if<
-             std::is_same<Input, wchar_t>::value
-             || std::is_same<Input, char16_t>::value
-             || std::is_same<Input, char32_t>::value,
-      Input>::type
-    {
         throw std::runtime_error("Parsing of wide characters is not yet supported");
       }
-
+    }
 
     /// Add all common functions for a POD type. All operators, and
     /// common conversions

include/chaiscript/dispatchkit/proxy_functions.hpp

@@ -777,29 +777,24 @@ namespace chaiscript
 
       private:
         template<typename Type>
-        auto do_call_impl(Class *o) const -> std::enable_if_t<std::is_pointer<Type>::value, Boxed_Value>
+        auto do_call_impl(Class *o) const
         {
+          if constexpr(std::is_pointer<Type>::value) {
             return detail::Handle_Return<Type>::handle(o->*m_attr);
-        }
+          } else {
-
-        template<typename Type>
-        auto do_call_impl(const Class *o) const -> std::enable_if_t<std::is_pointer<Type>::value, Boxed_Value>
-        {
-          return detail::Handle_Return<const Type>::handle(o->*m_attr);
-        }
-
-        template<typename Type>
-        auto do_call_impl(Class *o) const -> std::enable_if_t<!std::is_pointer<Type>::value, Boxed_Value>
-        {
             return detail::Handle_Return<typename std::add_lvalue_reference<Type>::type>::handle(o->*m_attr);
           }
-
-        template<typename Type>
-        auto do_call_impl(const Class *o) const -> std::enable_if_t<!std::is_pointer<Type>::value, Boxed_Value>
-        {
-          return detail::Handle_Return<typename std::add_lvalue_reference<typename std::add_const<Type>::type>::type>::handle(o->*m_attr);
         }
 
+        template<typename Type>
+        auto do_call_impl(const Class *o) const
+        {
+          if constexpr(std::is_pointer<Type>::value) {
+            return detail::Handle_Return<const Type>::handle(o->*m_attr);
+          } else {
+            return detail::Handle_Return<typename std::add_lvalue_reference<typename std::add_const<Type>::type>::type>::handle(o->*m_attr);
+          }
+        }
 
 
         static std::vector<Type_Info> param_types()

include/chaiscript/dispatchkit/type_conversions.hpp

@@ -562,24 +562,18 @@ namespace chaiscript
   /// \endcode
   /// 
   template<typename Base, typename Derived>
-  Type_Conversion base_class(typename std::enable_if<std::is_polymorphic<Base>::value && std::is_polymorphic<Derived>::value>::type* = nullptr)
+  Type_Conversion base_class()
   {
     //Can only be used with related polymorphic types
     //may be expanded some day to support conversions other than child -> parent
     static_assert(std::is_base_of<Base,Derived>::value, "Classes are not related by inheritance");
 
+    if constexpr(std::is_polymorphic<Base>::value && std::is_polymorphic<Derived>::value) {
       return chaiscript::make_shared<detail::Type_Conversion_Base, detail::Dynamic_Conversion_Impl<Base, Derived>>();
-  }
+    } else {
-
-  template<typename Base, typename Derived>
-  Type_Conversion base_class(typename std::enable_if<!std::is_polymorphic<Base>::value || !std::is_polymorphic<Derived>::value>::type* = nullptr)
-  {
-    //Can only be used with related polymorphic types
-    //may be expanded some day to support conversions other than child -> parent
-    static_assert(std::is_base_of<Base,Derived>::value, "Classes are not related by inheritance");
-
       return chaiscript::make_shared<detail::Type_Conversion_Base, detail::Static_Conversion_Impl<Base, Derived>>();
     }
+  }
 
 
   template<typename Callable>