refactor: 💥 quantity_point_like_traits now use numerical value instead of the quantity

Resolves #531

src/core/include/mp-units/framework/customization_points.h

@@ -174,9 +174,9 @@ struct quantity_like_traits;
  * @brief Provides support for external quantity point-like types
  *
  * The type trait should provide nested @c reference and @c origin objects,
- * a type alias @c rep, and static member functions @c to_quantity(T) that returns
- * the quantity being the offset of the point from the origin and
- * @c from_quantity(quantity<reference, rep>) that returns @c T form this quantity.
+ * a type alias @c rep, and static member functions @c to_numerical_value(T) that
+ * returns the raw value of the the quantity being the offset of the point from the
+ * origin and @c from_numerical_value(rep) that returns @c T formed this raw value.
  * Both return types should be encapsulated in either @c convert_explicitly or
  * @c convert_implicitly to specify if the conversion is allowed to happen implicitly.
  *

src/core/include/mp-units/framework/quantity_point.h

@@ -201,13 +201,14 @@ public:
               quantity<quantity_point_like_traits<QP>::reference, typename quantity_point_like_traits<QP>::rep>,
               quantity_type>
   constexpr explicit(
-    is_specialization_of<decltype(quantity_point_like_traits<QP>::to_quantity(std::declval<QP>())),
+    is_specialization_of<decltype(quantity_point_like_traits<QP>::to_numerical_value(std::declval<QP>())),
                          convert_explicitly> ||
     !std::convertible_to<
       quantity<quantity_point_like_traits<QP>::reference, typename quantity_point_like_traits<QP>::rep>, quantity_type>)
     // NOLINTNEXTLINE(google-explicit-constructor, hicpp-explicit-conversions)
     quantity_point(const QP& qp) :
-      quantity_from_origin_is_an_implementation_detail_(quantity_point_like_traits<QP>::to_quantity(qp).value)
+      quantity_from_origin_is_an_implementation_detail_(quantity_point_like_traits<QP>::to_numerical_value(qp).value,
+                                                        get_unit(quantity_point_like_traits<QP>::reference))
   {
   }
 
@@ -297,16 +298,20 @@ public:
                                                         typename quantity_point_like_traits<QP>::rep>>
   [[nodiscard]] explicit(
     is_specialization_of<
-      decltype(quantity_point_like_traits<QP>::from_quantity(quantity_from_origin_is_an_implementation_detail_)),
+      decltype(quantity_point_like_traits<QP>::from_numerical_value(
+        quantity_from_origin_is_an_implementation_detail_.numerical_value_is_an_implementation_detail_)),
       convert_explicitly> ||
     !std::convertible_to<quantity_type, quantity<quantity_point_like_traits<QP>::reference,
                                                  typename quantity_point_like_traits<QP>::rep>>) constexpr
   // NOLINTNEXTLINE(google-explicit-constructor, hicpp-explicit-conversions)
   operator QP_() const& noexcept(
-    noexcept(quantity_point_like_traits<QP>::from_quantity(quantity_from_origin_is_an_implementation_detail_)) &&
+    noexcept(quantity_point_like_traits<QP>::from_numerical_value(
+      quantity_from_origin_is_an_implementation_detail_.numerical_value_is_an_implementation_detail_)) &&
     std::is_nothrow_copy_constructible_v<rep>)
   {
-    return quantity_point_like_traits<QP>::from_quantity(quantity_from_origin_is_an_implementation_detail_).value;
+    return quantity_point_like_traits<QP>::from_numerical_value(
+             quantity_from_origin_is_an_implementation_detail_.numerical_value_is_an_implementation_detail_)
+      .value;
   }
 
   template<typename QP_, QuantityPointLike QP = std::remove_cvref_t<QP_>>
@@ -315,16 +320,19 @@ public:
                                                         typename quantity_point_like_traits<QP>::rep>>
   [[nodiscard]] explicit(
     is_specialization_of<
-      decltype(quantity_point_like_traits<QP>::from_quantity(quantity_from_origin_is_an_implementation_detail_)),
+      decltype(quantity_point_like_traits<QP>::from_numerical_value(
+        quantity_from_origin_is_an_implementation_detail_.numerical_value_is_an_implementation_detail_)),
       convert_explicitly> ||
     !std::convertible_to<quantity_type, quantity<quantity_point_like_traits<QP>::reference,
                                                  typename quantity_point_like_traits<QP>::rep>>) constexpr
   // NOLINTNEXTLINE(google-explicit-constructor, hicpp-explicit-conversions)
   operator QP_() && noexcept(
-    noexcept(quantity_point_like_traits<QP>::from_quantity(quantity_from_origin_is_an_implementation_detail_)) &&
+    noexcept(quantity_point_like_traits<QP>::from_numerical_value(
+      quantity_from_origin_is_an_implementation_detail_.numerical_value_is_an_implementation_detail_)) &&
     std::is_nothrow_move_constructible_v<rep>)
   {
-    return quantity_point_like_traits<QP>::from_quantity(std::move(quantity_from_origin_is_an_implementation_detail_))
+    return quantity_point_like_traits<QP>::from_numerical_value(
+             std::move(quantity_from_origin_is_an_implementation_detail_).numerical_value_is_an_implementation_detail_)
       .value;
   }
 
@@ -387,11 +395,10 @@ template<Quantity Q, PointOriginFor<Q::quantity_spec> PO>
 quantity_point(Q q, PO) -> quantity_point<Q::reference, PO{}, typename Q::rep>;
 
 template<QuantityPointLike QP>
-explicit(
-  is_specialization_of<decltype(quantity_point_like_traits<QP>::to_quantity(std::declval<QP>())), convert_explicitly>)
-  quantity_point(QP)
-    -> quantity_point<quantity_point_like_traits<QP>::reference, quantity_point_like_traits<QP>::point_origin,
-                      typename quantity_point_like_traits<QP>::rep>;
+explicit(is_specialization_of<decltype(quantity_point_like_traits<QP>::to_numerical_value(std::declval<QP>())),
+                              convert_explicitly>) quantity_point(QP)
+  -> quantity_point<quantity_point_like_traits<QP>::reference, quantity_point_like_traits<QP>::point_origin,
+                    typename quantity_point_like_traits<QP>::rep>;
 
 template<auto R1, auto PO1, typename Rep1, auto R2, typename Rep2>
 // TODO simplify when gcc catches up

src/core/include/mp-units/framework/quantity_point_concepts.h

@@ -159,14 +159,12 @@ concept QuantityPointLike = requires {
   typename quantity_point_like_traits<T>::rep;
   requires RepresentationOf<typename quantity_point_like_traits<T>::rep,
                             get_quantity_spec(quantity_point_like_traits<T>::reference).character>;
-} && requires(T qp, quantity<quantity_point_like_traits<T>::reference, typename quantity_point_like_traits<T>::rep> q) {
+} && requires(T qp, typename quantity_point_like_traits<T>::rep v) {
   {
-    quantity_point_like_traits<T>::to_quantity(qp)
-  } -> detail::ConversionSpecOf<
-    quantity<quantity_point_like_traits<T>::reference, typename quantity_point_like_traits<T>::rep>>;
-
+    quantity_point_like_traits<T>::to_numerical_value(qp)
+  } -> detail::ConversionSpecOf<typename quantity_point_like_traits<T>::rep>;
   {
-    quantity_point_like_traits<T>::from_quantity(q)
+    quantity_point_like_traits<T>::from_numerical_value(v)
   } -> detail::ConversionSpecOf<T>;
 };
 

src/systems/include/mp-units/systems/si/chrono.h

@@ -100,16 +100,16 @@ struct quantity_point_like_traits<std::chrono::time_point<C, std::chrono::durati
   static constexpr auto point_origin = chrono_point_origin<C>;
   using rep = Rep;
 
-  [[nodiscard]] static constexpr convert_implicitly<quantity<reference, rep>> to_quantity(const T& qp) noexcept(
+  [[nodiscard]] static constexpr convert_implicitly<rep> to_numerical_value(const T& tp) noexcept(
     std::is_nothrow_copy_constructible_v<rep>)
   {
-    return quantity{qp.time_since_epoch()};
+    return tp.time_since_epoch().count();
   }
 
-  [[nodiscard]] static constexpr convert_implicitly<T> from_quantity(const quantity<reference, rep>& q) noexcept(
+  [[nodiscard]] static constexpr convert_implicitly<T> from_numerical_value(const rep& v) noexcept(
     std::is_nothrow_copy_constructible_v<rep>)
   {
-    return T(q);
+    return T(std::chrono::duration<Rep, Period>(v));
   }
 };