Unit

PHP Units & Dimensions Library

A lightweight, type-safe PHP library for working with quantities, units, and dimensional analysis. Inspired by scientific computing needs, this library lets you define units, register them globally, perform arithmetic with dimension checking, and convert across compatible units.

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Features

• Immutable objects
• Dimensionally-aware arithmetic (add, subtract, multiply, divide)
• Automatic conversion between compatible units (e.g., cm to m)
• Support for compound units (e.g., m/s, kg⋅m²/s²)
• Enum-powered unit naming (Name enum)
• Custom unit registry

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Installation

composer require khaledalam/unit

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Basic Usage

<?php
// test.php

// __construct(string $name, Name|string $symbol, float $factor, Dimension $dimension)

require __DIR__ . '/vendor/autoload.php';

use KhaledAlam\Unit\Unit;
use KhaledAlam\Unit\Name;
use KhaledAlam\Unit\Dimension;
use KhaledAlam\Unit\Quantity;
use KhaledAlam\Unit\UnitRegistry;

// Register base units
UnitRegistry::register(new Unit(Name::M->value, Name::M, 1.0, new Dimension(['L' => 1])));

UnitRegistry::register(new Unit(Name::CM->value, Name::CM, 0.01, new Dimension(['L' => 1])));

// Create quantities
$length1 = Quantity::from(2.0, 'm');
$length2 = Quantity::from(100.0, 'cm');

// Add quantities (auto conversion)
$sum = $length1->add($length2); // Result: 3.0 m

echo $sum; // "3 m"

?>

output:

% php main.php
3 m

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Arithmetic Support

$velocity = Quantity::from(10, 'm')->divide(Quantity::from(2, 's'));  // 5 m/s
$area = Quantity::from(2, 'm')->multiply(Quantity::from(3, 'm'));     // 6 m²

All operations return new Quantity objects with proper dimensions and units.

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Unit Registration

Define and register your own units:

UnitRegistry::register(new Unit('inch', Name::INCH, 0.0254, new Dimension(['L' => 1])));

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Exception Handling

Operations on incompatible dimensions will throw an exception:

$mass = Quantity::from(5, 'kg');
$time = Quantity::from(3, 's');

$mass->add($time); // InvalidArgumentException

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Running Tests

This project uses PHP-internal's built-in run-tests.php format.

php run-tests.php tests/ --show-diff

Or

./vendor/bin/phpunit \
    --configuration phpunit.xml.dist \
    --testsuite=unit

Each test follows .phpt format and validates expected behavior.

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Project Structure

src/
  └── Unit/
       ├── Quantity.php
       ├── Unit.php
       ├── Dimension.php
       ├── UnitRegistry.php
       └── Name.php (enum)

tests/
  ├── add/
  ├── convert/
  ├── divide/
  └── ...

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About

Built by Khaled Alam to bring better scientific and data modeling features to PHP developers.