unit library

Provides compile-time dimension checking and scaling.

Similar to boost::units, but:

1. streamlined: assumes modern (c++20) support
2. supports fractional dimensions (rational powers)

Documentation

• xo-unit documentation [under construction]: documentation
• unit test coverage here: coverage

Example

#include "xo/unit/quantity.hpp"
#include "xo/unit/quantity_iostream.hpp"

namespace q = xo::qty::qty;
namespace u = xo::qty::u;

constexpr auto t = q::minutes(2);
constexpr auto d = q::kilometers(2.5);

constexpr auto t2 = t*t;   // unit will be min^-2
constexpr auto a = d / t2; // unit will be km.min^-2

// convert to m.s^-2
constexpr quantity<u::meter / (u::second * u::second)> a2 = a;

//constexpr quantity<u::meter> a3 = a;  // dimension mismatch, will not compile

// get dimensionless scale value
double x = a2.scale();

Getting Started

See full install instructions for other installation strategies.

build + install upstream dependencies

• github/Rconybea/xo-cmake
• github/Rconybea/xo-flatstring
• github/Rconybea/xo-ratio

(Below assumes they're installed using some common value for PREFIX)

fetch xo-unit

$ cd ~/proj
$ git clone https://github.com/rconybea/xo-unit

build + install

$ cd xo-unit
$ PREFIX=/usr/local  # or wherever you prefer
$ cmake -DCMAKE_INSTALL_PREFIX=${PREFIX} -S . -B .build
$ cmake --build .build -j
$ cmake --install .build

build documentation

$ cd xo-unit
$ cmake -DCMAKE_INSTALL_PREFIX=${PREFIX}  --build .build -- sphinx

When this completes, can point local browser to xo-unit/.build/docs/sphinx/index.html.

build for unit test coverage

Note that unit tests involve additional dependencies:

• github/Rconybea/xo-indentlog
• github/Rconybea/xo-randomgen

$ cd xo-unit
$ mkdir .build-ccov
$ cmake -DCMAKE_BUILD_TYPE=coverage -DCMAKE_INSTALL_PREFIX=${PREFIX} -DENABLE_TESTING=1 -B .build-ccov

run coverage-enabled unit tests:

$ cmake --build .build-ccov -- test

generate html+text coverage report:

$ .build-ccov/gen-ccov

To see coverage, can point local browser to xo-unit/.build-ccov/ccov/html/index.html

LSP support

$ cd xo-unit
$ ln -s .build/compile_commands.json  # lsp will look for compile_commands.json in the root of the source tree