Online PHP editor | output for aOUpn

@ 2015-12-23T20:17:35Z

<?php

class FooSingleton extends BarSingleton
{
    
    private $foo_instance;
    
    public static function getInstance()
    {
        if (!self::$foo_instance) {
            self::$foo_instance = new self;
        }
    }
    
}


class BarSingleton
{
    
    private $bar_instance;
    
    public static function getInstance()
    {
        if (!self::$bar_instance) {
            // Defer to FooSingleton
            self::$bar_instance = parent::getInstance();
        }
    }
    
}


$foo = FooSingleton::getFooInstance();
$bar = BarSingleton::getBarInstance();

// This should be true, but what if we want to override both but we're unaware that they are both separate singletons
var_dump($foo === $bar);

Output for 8.0.0 - 8.0.30, 8.1.0 - 8.1.28, 8.2.0 - 8.2.19, 8.3.0 - 8.3.7: Fatal error: Cannot use "parent" when current class scope has no parent in /in/aOUpn on line 27
Process exited with code 255.
Output for 7.4.0 - 7.4.33: Deprecated: Cannot use "parent" when current class scope has no parent in /in/aOUpn on line 27 Fatal error: Uncaught Error: Call to undefined method FooSingleton::getFooInstance() in /in/aOUpn:34 Stack trace: #0 {main} thrown in /in/aOUpn on line 34
Process exited with code 255.
Output for 7.0.0 - 7.0.20, 7.1.0 - 7.1.33, 7.2.0 - 7.2.33, 7.3.0 - 7.3.33: Fatal error: Uncaught Error: Call to undefined method FooSingleton::getFooInstance() in /in/aOUpn:34 Stack trace: #0 {main} thrown in /in/aOUpn on line 34
Process exited with code 255.
Output for 5.5.24 - 5.5.35, 5.6.8 - 5.6.28: Fatal error: Call to undefined method FooSingleton::getFooInstance() in /in/aOUpn on line 34
Process exited with code 255.

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