Design cleanup

- unknown_unit added
- examples refactored
- base_type renamed to downcast_base_type
- scaled_unit renamed to named_scaled_unit
- detail::reference_unit renamed to scaled_unit
- quantity_test cleanup

example/avg_velocity.cpp

@@ -0,0 +1,147 @@
+// 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.
+
+#include <units/physical/si/velocity.h>
+#include <iostream>
+
+namespace {
+
+constexpr units::si::velocity<units::si::metre_per_second, int>
+fixed_int_si_avg_speed(units::si::length<units::si::metre, int> d,
+                       units::si::time<units::si::second, int> t)
+{
+  return d / t;
+}
+
+constexpr units::si::velocity<units::si::metre_per_second>
+fixed_double_si_avg_speed(units::si::length<units::si::metre> d,
+                          units::si::time<units::si::second> t)
+{
+  return d / t;
+}
+
+template<typename U1, typename R1, typename U2, typename R2>
+constexpr units::Velocity AUTO si_avg_speed(units::si::length<U1, R1> d,
+                                            units::si::time<U2, R2> t)
+{
+  return d / t;
+}
+
+constexpr units::Velocity AUTO avg_speed(units::Length AUTO d, units::Time AUTO t)
+{
+  return d / t;
+}
+
+template<units::Length D, units::Time T, units::Velocity V>
+void print_result(D distance, T duration, V velocity)
+{
+  const auto result_in_kmph = units::quantity_cast<units::si::kilometre_per_hour>(velocity);
+  std::cout << "Average speed of a car that makes " << distance << " in "
+            << duration << " is " << result_in_kmph << ".\n";
+}
+
+void example()
+{
+  using namespace units;
+  using namespace units::si::literals;
+
+  // SI (int)
+  {
+    constexpr Length AUTO distance = 220km;        // constructed from a UDL
+    constexpr si::time<si::hour, int> duration(2); // constructed from a value
+
+    std::cout << "SI units with 'int' as representation\n";
+
+    print_result(distance, duration, fixed_int_si_avg_speed(distance, duration));
+    print_result(distance, duration, fixed_double_si_avg_speed(distance, duration));
+
+    // the framework will not allow a division (and multiplication) of different dimensions
+    // with two integral representation (at least one of them have to ba floating-point one)
+    print_result(distance, duration, si_avg_speed(quantity_cast<double>(distance), duration));
+    print_result(distance, duration, avg_speed(quantity_cast<double>(distance), duration));
+  }
+
+  // SI (double)
+  {
+    constexpr Length AUTO distance = 220.km;  // constructed from a UDL
+    constexpr si::time<si::hour> duration(2); // constructed from a value
+
+    std::cout << "\nSI units with 'double' as representation\n";
+
+    // conversion from a floating-point to an integral type is a truncating one so an explicit cast is needed
+    print_result(distance, duration, fixed_int_si_avg_speed(quantity_cast<int>(distance), quantity_cast<int>(duration)));
+
+    print_result(distance, duration, fixed_double_si_avg_speed(distance, duration));
+    print_result(distance, duration, si_avg_speed(distance, duration));
+    print_result(distance, duration, avg_speed(distance, duration));
+  }
+
+  // Customary Units (int)
+  {
+    constexpr Length AUTO distance = 140mi;        // constructed from a UDL
+    constexpr si::time<si::hour, int> duration(2); // constructed from a value
+
+    std::cout << "\nUS Customary Units with 'int' as representation\n";
+
+    // it is not possible to make a lossless conversion of miles to meters on an integral type
+    // (explicit cast needed)
+    print_result(distance, duration, fixed_int_si_avg_speed(quantity_cast<si::metre>(distance), duration));
+    print_result(distance, duration, fixed_double_si_avg_speed(distance, duration));
+
+    // the framework will not allow a division (and multiplication) of different dimensions
+    // with two integral representation (at least one of them have to ba floating-point one)
+    print_result(distance, duration, si_avg_speed(quantity_cast<double>(distance), duration));
+    print_result(distance, duration, avg_speed(quantity_cast<double>(distance), duration));
+  }
+
+  // Customary Units (double)
+  {
+    constexpr Length AUTO distance = 140.mi;  // constructed from a UDL
+    constexpr si::time<si::hour> duration(2); // constructed from a value
+
+    std::cout << "\nUS Customary Units with 'double' as representation\n";
+
+    // conversion from a floating-point to an integral type is a truncating one so an explicit cast is needed
+    // also it is not possible to make a lossless conversion of miles to meters on an integral type
+    // (explicit cast needed)
+    print_result(distance, duration, fixed_int_si_avg_speed(quantity_cast<si::metre, int>(distance), quantity_cast<int>(duration)));
+
+    print_result(distance, duration, fixed_double_si_avg_speed(distance, duration));
+    print_result(distance, duration, si_avg_speed(distance, duration));
+    print_result(distance, duration, avg_speed(distance, duration));
+  }
+}
+
+} // namespace
+
+int main()
+{
+  try {
+    example();
+  }
+  catch (const std::exception& ex) {
+    std::cerr << "Unhandled std exception caught: " << ex.what() << '\n';
+  }
+  catch (...) {
+    std::cerr << "Unhandled unknown exception caught\n";
+  }
+}