refactor: measurement example moved to a root examples directory

example/measurement.cpp

@@ -0,0 +1,156 @@
+// 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/isq/si/acceleration.h>
+#include <units/isq/si/length.h>
+#include <units/isq/si/speed.h>
+#include <units/isq/si/time.h>
+#include <units/quantity_io.h>
+#include <cmath>
+#include <exception>
+#include <iostream>
+
+namespace {
+
+template<class T>
+class measurement {
+public:
+  using value_type = T;
+
+  measurement() = default;
+
+  constexpr explicit measurement(const value_type& val, const value_type& err = {}) :
+      value_(val)
+  {
+    // it sucks that using declaration cannot be provided for a constructor initializer list
+    using namespace std;
+    uncertainty_ = abs(err);
+  }
+
+  constexpr const value_type& value() const { return value_; }
+  constexpr const value_type& uncertainty() const { return uncertainty_; }
+
+  constexpr value_type relative_uncertainty() const { return uncertainty() / value(); }
+  constexpr value_type lower_bound() const { return value() - uncertainty(); }
+  constexpr value_type upper_bound() const { return value() + uncertainty(); }
+
+  [[nodiscard]] constexpr measurement operator-() const { return measurement(-value(), uncertainty()); }
+
+  [[nodiscard]] friend constexpr measurement operator+(const measurement& lhs, const measurement& rhs)
+  {
+    using namespace std;
+    return measurement(lhs.value() + rhs.value(), hypot(lhs.uncertainty(), rhs.uncertainty()));
+  }
+
+  [[nodiscard]] friend constexpr measurement operator-(const measurement& lhs, const measurement& rhs)
+  {
+    using namespace std;
+    return measurement(lhs.value() - rhs.value(), hypot(lhs.uncertainty(), rhs.uncertainty()));
+  }
+
+  [[nodiscard]] friend constexpr measurement operator*(const measurement& lhs, const measurement& rhs)
+  {
+    const auto val = lhs.value() * rhs.value();
+    using namespace std;
+    return measurement(val, val * hypot(lhs.relative_uncertainty(), rhs.relative_uncertainty()));
+  }
+
+  [[nodiscard]] friend constexpr measurement operator*(const measurement& lhs, const value_type& value)
+  {
+    const auto val = lhs.value() * value;
+    return measurement(val, val * lhs.relative_uncertainty());
+  }
+
+  [[nodiscard]] friend constexpr measurement operator*(const value_type& value, const measurement& rhs)
+  {
+    const auto val = rhs.value() * value;
+    return measurement(val, val * rhs.relative_uncertainty());
+  }
+
+  [[nodiscard]] friend constexpr measurement operator/(const measurement& lhs, const measurement& rhs)
+  {
+    const auto val = lhs.value() / rhs.value();
+    using namespace std;
+    return measurement(val, val * hypot(lhs.relative_uncertainty(), rhs.relative_uncertainty()));
+  }
+
+  [[nodiscard]] friend constexpr measurement operator/(const measurement& lhs, const value_type& value)
+  {
+    const auto val = lhs.value() / value;
+    return measurement(val, val * lhs.relative_uncertainty());
+  }
+
+  [[nodiscard]] friend constexpr measurement operator/(const value_type& value, const measurement& rhs)
+  {
+    const auto val = value / rhs.value();
+    return measurement(val, val * rhs.relative_uncertainty());
+  }
+
+  [[nodiscard]] constexpr auto operator<=>(const measurement&) const = default;
+
+  friend std::ostream& operator<<(std::ostream& os, const measurement& v)
+  {
+    return os << v.value() << " ± " << v.uncertainty();
+  }
+
+private:
+  value_type value_{};
+  value_type uncertainty_{};
+};
+
+}  // namespace
+
+
+namespace {
+
+static_assert(units::Representation<measurement<double>>);
+
+void example()
+{
+  using namespace units::isq;
+
+  const auto a = si::acceleration<si::metre_per_second_sq, measurement<double>>(measurement(9.8, 0.1));
+  const auto t = si::time<si::second, measurement<double>>(measurement(1.2, 0.1));
+
+  const Speed auto v1 = a * t;
+#if UNITS_DOWNCAST_MODE == 0
+  std::cout << a << " * " << t << " = " << v1 << " = " << quantity_cast<si::dim_speed, si::kilometre_per_hour>(v1) << '\n';
+#else
+  std::cout << a << " * " << t << " = " << v1 << " = " << quantity_cast<si::kilometre_per_hour>(v1) << '\n';
+#endif
+
+  si::length<si::metre, measurement<double>> length(measurement(123., 1.));
+  std::cout << "10 * " << length << " = " << 10 * length << '\n';
+}
+
+}  // 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";
+  }
+}