Online PHP editor | rfc for 4TN3d

@ 2016-06-17T15:32:06Z

<?php

abstract class Singleton
{
    /**
     * @var Singleton[] The reference to *Singleton* instances of any child class.
     */
    private static $instances = array();
    
    /**
     * Returns the *Singleton* instance of this class.
     *
     * @return static The *Singleton* instance.
     */
    public static function getInstance()
    {
        if (!isset(self::$instances[static::class])) {
            self::$instances[static::class] = new static();
        }

        return self::$instances[static::class];
    }

    /**
     * Protected constructor to prevent creating a new instance of the
     * *Singleton* via the `new` operator from outside of this class.
     */
    protected function __construct()
    {
    }

    /**
     * Private clone method to prevent cloning of the instance of the
     * *Singleton* instance.
     *
     * @return void
     */
    private function __clone()
    {
    }

    /**
     * Private unserialize method to prevent unserializing of the *Singleton*
     * instance.
     *
     * @return void
     */
    private function __wakeup()
    {
    }
}

class SingletonChild extends Singleton
{
}

class AnotherChild extends Singleton
{
}

echo 'Expect: true, true, true, false' . PHP_EOL;

var_dump(SingletonChild::getInstance() === SingletonChild::getInstance());
var_dump(AnotherChild::getInstance() === AnotherChild::getInstance());

$a = AnotherChild::getInstance();
var_dump($a === AnotherChild::getInstance());
var_dump($a === SingletonChild::getInstance());

Output for git.master, git.master_jit, rfc.property-hooks: Warning: The magic method Singleton::__wakeup() must have public visibility in /in/4TN3d on line 48 Expect: true, true, true, false bool(true) bool(true) bool(true) bool(false)

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2022-12-01 RFC: Property hooks - included in PHP 8.4
2020-03-21 RFC: Is_Literal - declined
2020-12-04 Enumerations - included in PHP 8.1
2018-06-15 Typed Properties v2 - implemented in PHP 7.4
2016-08-12 Object typehint - included in PHP 7.2
2016-08-14 Arrow functions - withdrawn
2016-05-29 array_change_keys() - withdrawn
2016-04-19 Lexical scope support for anonymous classes - suspended
2016-04-17 Functional Interfaces - declined
2016-03-16 Typed Properties - superseded in favor of Typed Properties 2.0
2015-08-27 Callable Prototypes - declined
2015-05-01 Short Closures - declined / withdrawn in favor of Arrow Functions
2015-02-18 Scalar type hints v5 - included in PHP 7
2015-02-14 Union Types - declined
2013-09-22 Anonymous classes - included in PHP 7

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