PHP Comparable Objects Trait & Custom Comparison Convenience Method

A PHP library to allow for comparison of two objects with a comparison operator.

This library allows you to compare two objects using a value within the objects rather than the entirety of the object (the default for PHP).

Installation

This library is available on Packagist using Composer. Run this command within your composer project directory:

$ composer require jimbo2150/php-comparable

Usage (private value with convenience trait)

The comparable trait (ComparableTrait) requires a protected method, getComparableValue(), which does not publically expose the value to be compared. The convenience methods then use reflection to access the other object's value:

use Jimbo2150\PhpComparable\Trait\ComparableTrait;

// This class will compare the Person object's $age property.
class Person
{
	use ComparableTrait;

	public function __construct(private string $name, private int $age)
	{
		assert($age > 0);
	}

	public function getComparableValue(): mixed
	{
		return $this->age;
	}
}

$john = new Person('John', 29);
$karen = new Person('Karen', 24);

$john->compareTo($karen); // False, compares by equals (==) by default
$karen->compareTo($john, Operator::from('<')); // True, comparing with less than

Usage (private value with custom comparison)

You can also implement your own custom compare method by creating your own comparison method that utilizes the customCompareTo(callable $callback, ComparableTrait $compareTo, Operator $operator) convenience method and provide a callback (callable or Closure) that, when called, is passed the current object's comparison value, the comparison value of the object your are comparing to, and the operator as parameter values:

use Jimbo2150\PhpComparable\Trait\ComparableTrait;

class Score
{
	use ComparableTrait;

	public const MIN_REQUIRED_SCORE = 1;

	public function __construct(private float $score)
	{
	}

	public function compareDiff(object $other): bool|int
	{
		$operator = Operator::GREATER_THAN_OR_EQUAL;
		$diffFunction = fn (
			mixed $leftValue,
			mixed $rightValue,
			Operator $operator,
		): bool|int => $operator->compare(
			$leftValue - $rightValue,
			self::MIN_REQUIRED_SCORE
		);

		return $this->customCompareTo(
			$diffFunction,
			$other,
			$operator
		);
	}

	public function getComparableValue(): mixed
	{
		return $this->score;
	}
}

$score1 = new Score(2.4);
$score2 = new Score(0.7);
$score3 = new Score(0.2);

$score1->compareDiff($score2); // True, score is >= 1
$score2->compareDiff($score3); // False, score is less than 1