Singleton

Author: maxsite

README.md

@@ -6,6 +6,7 @@ See details on http://maxsite.org/page/php-patterns
 * "Fluent interface" (Structural)
 * "Factory method" / "Virtual Constructor" (Creational)
 * "Abstract factory" (Creational)
+* "Singleton" (Creational)
 
 
 (c) MaxSite.org, 2019, http://maxsite.org/

Singleton/index.php

@@ -0,0 +1,137 @@
+<?php
+
+/**
+ * Design pattern "Singleton" (Creational)
+ * This is demo code
+ * See for details: http://maxsite.org/page/php-patterns
+ */
+
+/**
+ * Base
+ */
+trait SingletonTrait
+{
+private static $instance;
+
+public static function getInstance()
+{
+if (empty(self::$instance)) self::$instance = new static();
+
+return self::$instance;
+}
+
+private function __construct()
+{
+}
+private function __clone()
+{
+}
+private function __wakeup()
+{
+}
+}
+
+/**
+ * Class for sample
+ */
+class Foo
+{
+/**
+ * Add SingletonTrait to this class
+ */
+use SingletonTrait;
+
+/**
+ * Class's own methods...
+ */
+private $var = [];
+
+public function addVal($v)
+{
+$this->var[] = $v;
+}
+
+public function getVal()
+{
+return $this->var;
+}
+}
+
+
+/**
+ * demo
+ */
+
+echo '<pre>'; // for print in browser
+
+# $foo = new Foo(); // Error: Call to private Foo::__construct()
+
+/**
+ * get instance in $foo1
+ */
+$foo1 = Foo::getInstance();
+
+/**
+ * add values
+ */
+$foo1->addVal('first');
+$foo1->addVal('second');
+
+/**
+ * control
+ */
+print_r($foo1->getVal()); 
+/*
+ Array
+ (
+ [0] => first
+ [1] => second
+ )
+ */
+
+/**
+ * new variable $foo2
+ */
+$foo2 = Foo::getInstance();
+print_r($foo2->getVal());
+/*
+ Array
+ (
+ [0] => first
+ [1] => second
+ )
+ */
+
+/**
+ * add value to $foo
+ */
+$foo1->addVal('new value');
+
+/**
+ * control $foo1
+ */
+print_r($foo1->getVal());
+/*
+ Array
+ (
+ [0] => first
+ [1] => second
+[2] => new value
+ )
+ */
+
+/**
+ * control $foo2
+ */
+print_r($foo2->getVal());
+/*
+ Array
+ (
+ [0] => first
+ [1] => second
+[2] => new value
+ )
+ */
+
+
+# end of file