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xo-unit: promote to common repr in mixed-type operator* w/ quantity

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Avoid truncating when, for example, multiplying
quantity<Unit, int> * double.

Add targeted unit test for this
This commit is contained in:
Roland Conybeare 2024-05-07 10:38:38 -04:00
commit df6cfbb25c
2 changed files with 22 additions and 1 deletions
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4
include/xo/unit/quantity.hpp
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@ -106,7 +106,9 @@ namespace xo {
template <typename Dimensionless>
requires std::is_arithmetic_v<Dimensionless>
constexpr auto scale_by(Dimensionless x) const {
return quantity(x * this->scale_);
using r_repr_type = std::common_type_t<repr_type, Dimensionless>;
return quantity<s_unit, r_repr_type>(x * this->scale_);
}
// divide_by

19
utest/quantity.test.cpp
View file

@ -421,6 +421,25 @@ namespace xo {
} /*TEST_CASE(quantity.mult2)*/
TEST_CASE("quantity.mult3", "[quantity.mult]") {
constexpr auto ng = qty::nanogram;
constexpr auto l_qty = 7.55 * ng;
constexpr auto r_qty = ng * 7.55;
static_assert(l_qty.unit().n_bpu() == 1);
static_assert(l_qty.unit().bpu_v_[0].native_dim() == dim::mass);
static_assert(l_qty.unit().bpu_v_[0].power() == xo::ratio::ratio(1,1));
static_assert(l_qty.unit().bpu_v_[0].scalefactor() == xo::ratio::ratio(1,1000000000));
static_assert(l_qty.scale() == 7.55);
static_assert(r_qty.unit().n_bpu() == 1);
static_assert(r_qty.unit().bpu_v_[0].native_dim() == dim::mass);
static_assert(r_qty.unit().bpu_v_[0].power() == xo::ratio::ratio(1,1));
static_assert(r_qty.unit().bpu_v_[0].scalefactor() == xo::ratio::ratio(1,1000000000));
static_assert(r_qty.scale() == 7.55);
}
TEST_CASE("quantity.div2", "[quantity.div]") {
constexpr auto ms = qty::milliseconds(1.0);