Fix #580 by using a fixed-point implementation for unit conversions using integer representations #615
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@@ -70,15 +70,37 @@ class measurement { | |
| [[nodiscard]] friend constexpr measurement operator+(const measurement& lhs, const measurement& rhs) | ||
| { | ||
| using namespace std; | ||
| return measurement{std::in_place, lhs.value() + rhs.value(), hypot(lhs.uncertainty(), rhs.uncertainty())}; | ||
| } | ||
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| [[nodiscard]] friend constexpr measurement operator-(const measurement& lhs, const measurement& rhs) | ||
| { | ||
| using namespace std; | ||
| return measurement{std::in_place, lhs.value() - rhs.value(), hypot(lhs.uncertainty(), rhs.uncertainty())}; | ||
| } | ||
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| template<typename To, mp_units::Magnitude M> | ||
| [[nodiscard]] constexpr measurement<To> scale(std::type_identity<measurement<To>>, M scaling_factor) const | ||
| { | ||
| constexpr std::type_identity<To> to_value_type; | ||
| return measurement<To>{ | ||
| std::in_place, | ||
| mp_units::scale(to_value_type, scaling_factor, value()), | ||
| mp_units::scale(to_value_type, scaling_factor, value()), | ||
| }; | ||
| } | ||
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| template<mp_units::Magnitude M> | ||
| [[nodiscard]] constexpr auto scale(M scaling_factor) const | ||
| { | ||
| return measurement{ | ||
| std::in_place, | ||
| mp_units::scale(scaling_factor, value()), | ||
| mp_units::scale(scaling_factor, value()), | ||
| }; | ||
| } | ||
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| [[nodiscard]] friend constexpr measurement operator*(const measurement& lhs, const measurement& rhs) | ||
| { | ||
| const auto val = lhs.value() * rhs.value(); | ||
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@@ -127,15 +149,23 @@ class measurement { | |
| private: | ||
| value_type value_{}; | ||
| value_type uncertainty_{}; | ||
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| // NOLINTNEXTLINE(bugprone-easily-swappable-parameters) | ||
| constexpr measurement(std::in_place_t, value_type val, value_type err) : | ||
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There was a problem hiding this comment. This is not the right way of using This is not the case here. We initialize two members with one argument each. There was a problem hiding this comment. If you would like to have in-place like construction for type then probably something like piecewise_construct is needed. There was a problem hiding this comment. Yeah, I just wanted a tag to select the private constructor, indicating "I know what I'm doing - I guarantee that There was a problem hiding this comment. We can either remove it or use a new dedicated tag. Maybe something similar to: mp-units/example/include/validated_type.h Lines 43 to 44 in 727a898 |
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| value_(std::move(val)), uncertainty_(std::move(err)) | ||
| { | ||
| } | ||
| }; | ||
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| } // namespace | ||
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| template<typename T> | ||
| constexpr bool mp_units::is_scalar<measurement<T>> = true; | ||
| template<typename T> | ||
| constexpr bool mp_units::is_vector<measurement<T>> = true; | ||
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| static_assert(mp_units::RepresentationOf<measurement<int>, mp_units::quantity_character::scalar>); | ||
| static_assert(mp_units::RepresentationOf<measurement<double>, mp_units::quantity_character::scalar>); | ||
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| namespace { | ||
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This
type_identityusage here is quite novel. I understand the rationale, but maybe we can find a more traditional way of doing it? @JohelEGP, do you have any ideas here?There was a problem hiding this comment.
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The idea comes from
boost::hana::type. Would be great if the standard had its own dedicated "type tag".