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UnitOfMeasurement

UnitOfMeasurement represents a single unit within a quantity type. Each instance holds a name, a conversion factor relative to the native unit, and a list of aliases.

Construction​

public function __construct(string $name, float $conversionFactor)

The name passed to the constructor is also registered as the first alias. The conversion factor expresses how many native units one of this unit equals.

use Renfordt\UnitLib\UnitOfMeasurement;

$foot = new UnitOfMeasurement('ft', 0.3048); // 1 ft = 0.3048 m

The native unit of a quantity always has a conversion factor of 1.0, because it is the unit all others are measured against.

Aliases​

A unit can carry several names. Aliases let users supply common spellings and abbreviations:

$meter = new UnitOfMeasurement('m', 1);
$meter->addAlias('meter');
$meter->addAlias('metre');
$meter->addAlias('meters');

isAlias() checks whether a given string matches the unit's name or any of its aliases:

$meter->isAlias('metre'); // true
$meter->isAlias('ft');     // false

Property access​

conversionFactor and aliases are exposed through PHP 8.4 property hooks as read-only virtual properties. Access them as properties, not method calls:

$foot->conversionFactor; // 0.3048
$foot->aliases;          // ['ft', ...]
$foot->name;             // "ft"

Where units are defined​

Units are registered inside each quantity's initialise() method using addUnit(). The first unit added becomes the native unit. See Adding new quantities for how to define units for a new quantity type.