README

Equalable

The equalable library provides a single interface that defines a method that implementing classes can use to provide custom equality determination. This is useful for value objects and entities alike, since the former might want to allow equality checks against scalar types, and the latter need to exclude all encapsulated values from the equality determination which are not part of their identity defining values.

• Installation
• Usage
• Testing

Installation

Open a terminal, enter your project directory and execute the following command to add this package to your dependencies:

composer require fleshgrinder/equalable

This command requires you to have Composer installed globally, as explained in the installation chapter of the Composer documentation.

Usage

Simply implement the interface and the required equals method. The actual implementation of the method’s body depends on the use-case. Value objects for instance might want to allow equality checks against scalar types, e.g.:

final class UserId implements Equalable {
	private $uid;

	// ...

	public function equals($other): bool {
		if ($other instanceof $this) {
			$other = $other->uid;
		}

		return \is_int($other) && $this->uid === $other;
	}
}

Entities on the other hand want to exclude all encapsulated values which are not part of their identity defining values from the determination, e.g.:

final class User implements Equalable {
	private $uid;
	private $name;
	private $email;

	// ...

	public function equals($other): bool {
		return $other instanceof $this && $this->uid->equals($other->uid);
	}
}

Testing

There are not tests since this library provides a single interface, which obviously has no implementation.