php-basics/docs/files/src/Traits/Singleton.php.txt

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<?php
/**
* PHP Basics
*
* Copyright (C) 2024 Sebastian Meyer <sebastian.meyer@opencultureconsulting.com>
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
declare(strict_types=1);
namespace OCC\Basics\Traits;
use LogicException;
/**
* Allows just a single instance of the class using this trait.
*
* @author Sebastian Meyer <sebastian.meyer@opencultureconsulting.com>
* @package Basics\Traits
*/
trait Singleton
{
/**
* Holds the singleton instance.
*
* @var array<string, static>
*
* @internal
*/
private static array $singleton = [];
/**
* Get a singleton instance of this class.
*
* @param mixed ...$args Constructor parameters
*
* @return static The singleton instance
*
* @api
*/
final public static function getInstance(mixed ...$args): static
{
if (!isset(static::$singleton[static::class])) {
static::$singleton[static::class] = new static(...$args);
}
return static::$singleton[static::class];
}
/**
* This is a singleton class, thus the constructor is private.
*
* Usage: Get an instance of this class by calling static::getInstance()
*
* @return void
*/
abstract private function __construct();
/**
* This is a singleton class, thus cloning is prohibited.
*
* @return void
*
* @throws LogicException
*
* @internal
*/
final public function __clone(): void
{
throw new LogicException('Cloning a singleton is prohibited.');
}
}