Editing Facade pattern (section)

== Usage ==
A Facade is used when an easier or simpler interface to an underlying object is desired.<ref>{{cite book | last1 = Freeman | first1 = Eric | last2 = Freeman | first2 = Elisabeth | last3 = Sierra | first3 = Kathy | last4 = Bates | first4 = Bert | editor1-last = Hendrickson | editor1-first = Mike | editor2-last = Loukides | editor2-first = Mike | year = 2004 | title = Head First Design Patterns | volume = 1 | pages = 243, 252, 258, 260 | publisher = O'Reilly | format = paperback | isbn = 978-0-596-00712-6 | access-date = 2012-07-02 | url = https://www.goodreads.com/book/show/58128.Head_First_Design_Patterns
}}</ref> Alternatively, an [[Adapter pattern|adapter]] can be used when the wrapper must respect a particular interface and must support [[Polymorphism (computer science)|polymorphic]] behavior. A [[Decorator pattern|decorator]] makes it possible to add or alter behavior of an interface at run-time.
{| class="wikitable"
! Pattern !! Intent
|-
| [[Adapter_pattern|Adapter]] || Converts one interface to another so that it matches what the client is expecting
|-
| [[Decorator_pattern|Decorator]] || Dynamically adds responsibility to the interface by wrapping the original code
|-
| Facade || Provides a simplified interface
|}

The facade pattern is typically used when
* a simple interface is required to access a complex system,
* a system is very complex or difficult to understand,
* an entry point is needed to each level of layered software, or
* the abstractions and implementations of a subsystem are tightly coupled.