feat: 💥 initial implementation of implicit point origins

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

@@ -1,38 +0,0 @@
-// The MIT License (MIT)
-//
-// Copyright (c) 2018 Mateusz Pusz
-//
-// Permission is hereby granted, free of charge, to any person obtaining a copy
-// of this software and associated documentation files (the "Software"), to deal
-// in the Software without restriction, including without limitation the rights
-// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
-// copies of the Software, and to permit persons to whom the Software is
-// furnished to do so, subject to the following conditions:
-//
-// The above copyright notice and this permission notice shall be included in all
-// copies or substantial portions of the Software.
-//
-// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
-// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
-// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
-// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
-// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
-// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
-// SOFTWARE.
-
-#pragma once
-
-#include <mp-units/quantity_point.h>
-#include <mp-units/systems/si/units.h>
-
-namespace mp_units::si {
-
-// clang-format off
-inline constexpr struct absolute_zero : absolute_point_origin<absolute_zero, isq::thermodynamic_temperature> {} absolute_zero;
-inline constexpr struct zeroth_kelvin : decltype(absolute_zero) {} zeroth_kelvin;
-
-inline constexpr struct ice_point : relative_point_origin<absolute_zero + 273.15 * kelvin> {} ice_point;
-inline constexpr struct zeroth_degree_Celsius : decltype(ice_point) {} zeroth_degree_Celsius;
-// clang-format on
-
-}  // namespace mp_units::si

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

@@ -23,7 +23,6 @@
 #pragma once
 
 #include <mp-units/systems/si/constants.h>
-#include <mp-units/systems/si/point_origins.h>
 #include <mp-units/systems/si/prefixes.h>
 #include <mp-units/systems/si/unit_symbols.h>
 #include <mp-units/systems/si/units.h>

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

@@ -22,6 +22,7 @@
 
 #pragma once
 
+#include <mp-units/quantity_point.h>
 #include <mp-units/systems/isq/atomic_and_nuclear_physics.h>
 #include <mp-units/systems/isq/base_quantities.h>
 #include <mp-units/systems/isq/space_and_time.h>
@@ -39,7 +40,11 @@ inline constexpr struct metre : named_unit<"m", kind_of<isq::length>> {} metre;
 inline constexpr struct gram : named_unit<"g", kind_of<isq::mass>> {} gram;
 inline constexpr struct kilogram : decltype(kilo<gram>) {} kilogram;
 inline constexpr struct ampere : named_unit<"A", kind_of<isq::electric_current>> {} ampere;
-inline constexpr struct kelvin : named_unit<"K", kind_of<isq::thermodynamic_temperature>> {} kelvin;
+
+inline constexpr struct absolute_zero : absolute_point_origin<absolute_zero, isq::thermodynamic_temperature> {} absolute_zero;
+inline constexpr struct zeroth_kelvin : decltype(absolute_zero) {} zeroth_kelvin;
+inline constexpr struct kelvin : named_unit<"K", kind_of<isq::thermodynamic_temperature>, zeroth_kelvin> {} kelvin;
+
 inline constexpr struct mole : named_unit<"mol", kind_of<isq::amount_of_substance>> {} mole;
 inline constexpr struct candela : named_unit<"cd", kind_of<isq::luminous_intensity>> {} candela;
 
@@ -68,7 +73,11 @@ inline constexpr struct siemens : named_unit<"S", one / ohm> {} siemens;
 inline constexpr struct weber : named_unit<"Wb", volt * second> {} weber;
 inline constexpr struct tesla : named_unit<"T", weber / square(metre)> {} tesla;
 inline constexpr struct henry : named_unit<"H", weber / ampere> {} henry;
-inline constexpr struct degree_Celsius : named_unit<basic_symbol_text{"°C", "`C"}, kelvin> {} degree_Celsius;
+
+inline constexpr struct ice_point : relative_point_origin<quantity_point{273.15 * kelvin}> {} ice_point;
+inline constexpr struct zeroth_degree_Celsius : decltype(ice_point) {} zeroth_degree_Celsius;
+inline constexpr struct degree_Celsius : named_unit<basic_symbol_text{"°C", "`C"}, kelvin, zeroth_degree_Celsius> {} degree_Celsius;
+
 inline constexpr struct lumen : named_unit<"lm", candela * steradian> {} lumen;
 inline constexpr struct lux : named_unit<"lx", lumen / square(metre)> {} lux;
 inline constexpr struct becquerel : named_unit<"Bq", one / second, kind_of<isq::activity>> {} becquerel;

src/systems/usc/include/mp-units/systems/usc/usc.h

@@ -110,9 +110,9 @@ inline constexpr struct troy_pound : named_unit<"lb t", mag<12> * troy_once> {}
 inline constexpr struct inch_of_mercury : named_unit<"inHg", mag<ratio(3'386'389, 1'000)> * si::pascal> {} inch_of_mercury;
 
 // https://en.wikipedia.org/wiki/United_States_customary_units#Temperature
-inline constexpr struct degree_Fahrenheit : named_unit<basic_symbol_text{"°F", "`F"}, mag<ratio{5, 9}> * si::degree_Celsius> {} degree_Fahrenheit;
+inline constexpr struct zeroth_degree_Fahrenheit : relative_point_origin<si::zeroth_degree_Celsius - 32 * (mag<ratio{5, 9}> * si::degree_Celsius)> {} zeroth_degree_Fahrenheit;
+inline constexpr struct degree_Fahrenheit : named_unit<basic_symbol_text{"°F", "`F"}, mag<ratio{5, 9}> * si::degree_Celsius, zeroth_degree_Fahrenheit> {} degree_Fahrenheit;
 
-inline constexpr struct zeroth_degree_Fahrenheit : relative_point_origin<si::zeroth_degree_Celsius - 32 * degree_Fahrenheit> {} zeroth_degree_Fahrenheit;
 // clang-format on
 
 namespace unit_symbols {