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jrfnl
2014-12-08 03:26:54 +01:00
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pages/Design-Patterns.md
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---
layout: page
title: Design Patterns
title: Design Patterns
---
# Design Patterns
@@ -134,10 +134,16 @@ var_dump($anotherObj === SingletonChild::getInstance()); // bool(true)
The code above implements the singleton pattern using a [*static* variable](http://php.net/language.variables.scope#language.variables.scope.static) and the static creation method `getInstance()`.
Note the following:
* The constructor [`__construct`](http://php.net/language.oop5.decon#object.construct) is declared as protected to prevent creating a new instance outside of the class via the `new` operator.
* The magic method [`__clone`](http://php.net/language.oop5.cloning#object.clone) is declared as private to prevent cloning of an instance of the class via the [`clone`](http://php.net/language.oop5.cloning) operator.
* The magic method [`__wakeup`](http://php.net/language.oop5.magic#object.wakeup) is declared as private to prevent unserializing of an instance of the class via the global function [`unserialize()`](http://php.net/function.unserialize).
* A new instance is created via [late static binding](http://php.net/language.oop5.late-static-bindings) in the static creation method `getInstance()` with the keyword `static`. This allows the subclassing of the class `Singleton` in the example.
* The constructor [`__construct`](http://php.net/language.oop5.decon#object.construct) is declared as protected to
prevent creating a new instance outside of the class via the `new` operator.
* The magic method [`__clone`](http://php.net/language.oop5.cloning#object.clone) is declared as private to prevent
cloning of an instance of the class via the [`clone`](http://php.net/language.oop5.cloning) operator.
* The magic method [`__wakeup`](http://php.net/language.oop5.magic#object.wakeup) is declared as private to prevent
unserializing of an instance of the class via the global function [`unserialize()`](http://php.net/function.unserialize)
.
* A new instance is created via [late static binding](http://php.net/language.oop5.late-static-bindings) in the static
creation method `getInstance()` with the keyword `static`. This allows the subclassing of the class `Singleton` in the
example.
The singleton pattern is useful when we need to make sure we only have a single instance of a class for the entire
request lifecycle in a web application. This typically occurs when we have global objects (such as a Configuration