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xo-unit: doc/example streamlining

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This commit is contained in:
Roland Conybeare 2024-05-04 12:00:31 -04:00
commit 1b8fabe923
2 changed files with 37 additions and 23 deletions
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55
docs/examples.rst
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@ -144,7 +144,7 @@ See ``xo-unit/example/ex3`` for code below
.. code-block:: cpp
:linenos:
:emphasize-lines: 11-12
:emphasize-lines: 12-13
int
main () {
@ -173,12 +173,12 @@ with output:
Remarks:
* Assignment to ``t`` converted to representation ``double``.
We could have used :code:`quantity<nu::second, int>` to preserve
right-hand-side representation.
- Assignment to ``t`` converted to representation ``double``.
We could have used :code:`quantity<nu::second, int>` to preserve
right-hand-side representation.
Scale conversion triggered by arithmetic
----------------------------------------
Scale conversion and arithmetic
-------------------------------
When representing a particular quantity,
xo-unit uses at most one scale for each :term:`basis dimension` associated with the unit for that quantity.
@ -210,37 +210,50 @@ with output:
t1: 1ms, t2: 1min, t1*t2: 60000ms^2
Dimensionless quantities collapse automatically
-----------------------------------------------
Dimensionless quantities unwrap implicitly
------------------------------------------
See ``xo-unit/examples/ex4`` for code below.
.. code-block:: cpp
:linenos:
:emphasize-lines: 14-15
:emphasize-lines: 23,26
#include "xo/unit/quantity.hpp"
#include "xo/unit/quantity_iostream.hpp"
#include <iostream>
int main() {
namespace u = xo::unit;
namespace qty = xo::units::qty;
using namespace std;
int
main () {
namespace q = xo::qty::qty;
auto t1 = qty::milliseconds(1);
auto t2 = qty::minutes(1);
auto r1 = t1 / t2.with_repr<double>();
auto r2 = t2 / t1.with_repr<double>();
auto t1 = q::milliseconds(1);
auto t2 = q::minutes(1);
static_assert<same_as<decltype(r1), double>);
static_assert<same_as<decltype(r2), double>);
auto r1 = t1 / with_repr<double>(t2);
cerr << "t1: " << t1 << ", t2: " << t2 << ", t1/t2: " << r1 << ", t2/t1: " << r2 << endl;
static_assert(r1.is_dimensionless());
static_assert(!t2.is_dimensionless());
static_assert(std::same_as<static_cast<double>(r1), double>);
// static_assert fails b/c static_cast only available for dimensionless quantity
//static_assert(std::same_as<decltype(static_cast<double>(t2)), double>);
// r1_value: assignment compiles, since r1 dimensionless
double r1_value = r1;
// r2_value: assignment won't compile, 'cannot convert' error
//double r2_value = t2;
std::cerr << "t1: " << t1 << ", t2: " << t2 << ", t1/t2: " << r1_value << std::endl;
}
with output:
.. code-block::
t1: 1ms, t2: 1min, t1/t2: 1.66667e-05, t2/t1: 60000
t1: 1ms, t2: 1min, t1/t2: 1.66667e-05
Fractional dimension

5
example/ex4/ex4.cpp
View file

@ -6,9 +6,7 @@
int
main () {
//namespace u = xo::qty::units;
namespace q = xo::qty::qty;
using xo::qty::with_repr;
auto t1 = q::milliseconds(1);
auto t2 = q::minutes(1);
@ -18,6 +16,9 @@ main () {
static_assert(r1.is_dimensionless());
static_assert(!t2.is_dimensionless());
static_assert(std::same_as<decltype(static_cast<double>(r1)), double>);
//static_assert(std::same_as<decltype(static_cast<double>(t2)), double>);
/* r1_value: assignment compiles, since r1 dimensionless */
double r1_value = r1;