forked from mpusz/mp-units
124 lines
5.6 KiB
Markdown
124 lines
5.6 KiB
Markdown
[](./LICENSE.md)
|
|
[](https://en.cppreference.com/w/cpp/compiler_support#cpp20)
|
|
|
|
[](https://github.com/mpusz/mp-units/actions?query=workflow%3A%22Conan%20CI%22+branch%3Amaster)
|
|
[](https://github.com/mpusz/mp-units/actions?query=workflow%3A%22CMake+Test+Package+CI%22+branch%3Amaster)
|
|
[](https://github.com/mpusz/mp-units/actions?query=workflow%3A%22Check%20CI%22+branch%3Amaster)
|
|
[](https://github.com/mpusz/mp-units/actions?query=workflow%3ADocumentation+branch%3Amaster)
|
|
|
|
[](https://conan.io/center/mp-units)
|
|
[](https://mpusz.jfrog.io/ui/packages/conan:%2F%2Fmp-units/2.1.0)
|
|
|
|
|
|
# `mp-units` - A Physical Quantities and Units library for C++
|
|
|
|
**The mp-units library might be the subject of ISO standardization for C++29.
|
|
More on this can be found in ISO C++ paper [P1935](https://wg21.link/p1935).
|
|
We are actively looking for parties interested in field trialing the library.**
|
|
|
|
[](https://gitpod.io/#https://github.com/mpusz/mp-units)
|
|
|
|
|
|
## Video Introduction
|
|
|
|
A brief introduction to the library's interfaces and the rationale for changes in the version 2.0
|
|
of **mp-units** were provided in detail by [Mateusz Pusz](https://github.com/mpusz) in the
|
|
["The Power of C++ Templates With mp-units: Lessons Learned & a New Library Design" talk at the C++ on Sea 2023 conference](https://www.youtube.com/watch?v=eUdz0WvOMm0).
|
|
|
|
|
|
## Documentation
|
|
|
|
An extensive project documentation can be found on [mp-units GitHub Pages](https://mpusz.github.io/mp-units).
|
|
It includes installation instructions and a detailed user's guide.
|
|
|
|
|
|
## Terms and Definitions
|
|
|
|
This project uses the official metrology vocabulary defined by the ISO and BIPM.
|
|
Please familiarize yourself with those terms to better understand the documentation
|
|
and improve domain-related communication and discussions. You can find essential
|
|
project-related definitions in [our documentation's "Glossary" chapter](https://mpusz.github.io/mp-units/latest/appendix/glossary).
|
|
Even more terms are provided in the official vocabulary of the [ISO](https://www.iso.org/obp/ui#iso:std:iso-iec:guide:99:ed-1:v2:en)
|
|
and [BIPM](https://jcgm.bipm.org/vim/en).
|
|
|
|
|
|
## TL;DR
|
|
|
|
`mp-units` is a compile-time enabled Modern C++ library that provides compile-time dimensional
|
|
analysis and unit/quantity manipulation.
|
|
|
|
Here is a small example of possible operations:
|
|
|
|
```cpp
|
|
#include <mp-units/systems/si/si.h>
|
|
|
|
using namespace mp_units;
|
|
using namespace mp_units::si::unit_symbols;
|
|
|
|
// simple numeric operations
|
|
static_assert(10 * km / 2 == 5 * km);
|
|
|
|
// unit conversions
|
|
static_assert(1 * h == 3600 * s);
|
|
static_assert(1 * km + 1 * m == 1001 * m);
|
|
|
|
// derived quantities
|
|
static_assert(1 * km / (1 * s) == 1000 * m / s);
|
|
static_assert(2 * km / h * (2 * h) == 4 * km);
|
|
static_assert(2 * km / (2 * km / h) == 1 * h);
|
|
|
|
static_assert(2 * m * (3 * m) == 6 * m2);
|
|
|
|
static_assert(10 * km / (5 * km) == 2 * one);
|
|
|
|
static_assert(1000 / (1 * s) == 1 * kHz);
|
|
```
|
|
|
|
_Try it on the [Compiler Explorer](https://godbolt.org/z/81Ev7qhTd)._
|
|
|
|
This library heavily uses C++20 features (concepts, classes as NTTPs, ...). Thanks to
|
|
them the user gets a powerful but still easy to use interfaces and all unit conversions
|
|
and dimensional analysis can be performed without sacrificing on runtime performance or
|
|
accuracy. Please see the below example for a quick preview of basic library features:
|
|
|
|
```cpp
|
|
#include <mp-units/format.h>
|
|
#include <mp-units/ostream.h>
|
|
#include <mp-units/systems/international/international.h>
|
|
#include <mp-units/systems/isq/isq.h>
|
|
#include <mp-units/systems/si/si.h>
|
|
#include <iostream>
|
|
|
|
using namespace mp_units;
|
|
|
|
constexpr QuantityOf<isq::speed> auto avg_speed(QuantityOf<isq::length> auto d,
|
|
QuantityOf<isq::time> auto t)
|
|
{
|
|
return d / t;
|
|
}
|
|
|
|
int main()
|
|
{
|
|
using namespace mp_units::si::unit_symbols;
|
|
using namespace mp_units::international::unit_symbols;
|
|
|
|
constexpr quantity v1 = 110 * km / h;
|
|
constexpr quantity v2 = 70 * mph;
|
|
constexpr quantity v3 = avg_speed(220. * isq::distance[km], 2 * h);
|
|
constexpr quantity v4 = avg_speed(isq::distance(140. * mi), 2 * h);
|
|
constexpr quantity v5 = v3.in(m / s);
|
|
constexpr quantity v6 = value_cast<m / s>(v4);
|
|
constexpr quantity v7 = value_cast<int>(v6);
|
|
|
|
std::cout << v1 << '\n'; // 110 km/h
|
|
std::cout << v2 << '\n'; // 70 mi/h
|
|
std::cout << std::format("{}", v3) << '\n'; // 110 km/h
|
|
std::cout << std::format("{:*^14}", v4) << '\n'; // ***70 mi/h****
|
|
std::cout << std::format("{:%Q in %q}", v5) << '\n'; // 30.5556 in m/s
|
|
std::cout << std::format("{0:%Q} in {0:%q}", v6) << '\n'; // 31.2928 in m/s
|
|
std::cout << std::format("{:%Q}", v7) << '\n'; // 31
|
|
}
|
|
```
|
|
|
|
_Try it on the [Compiler Explorer](https://godbolt.org/z/Tsesa1Pvq)._
|