Decorator - Design Pattern
Simplest explanation I’ve heard of the decorator pattern is it’s “used to extend the functionality of a single object without affecting any other instances of the same class.” The decorator pattern is used to achieving a separation of concerns and is essential tool in the Open/Closed principle.
Here is an example:
require 'delegate' class Person def speak 'hello' end def age 30 end end class LatinDecorator < SimpleDelegator # modifies existing functionality def speak "'hola' means '#{__getobj__.speak}'" end # adds new functionality def dance 'cha-cha-cha' end end person = Person.new wrapper = LatinDecorator.new(person) wrapper.speak # => "'hola' means 'hello'" wrapper.age # => 30 wrapper.dance # => 'cha-cha-cha'
Most of the information from this blog post came from this blog post. Writing it in my own blog post helps me reference and learn it a bit faster.
Use the decorator pattern when you wish to extend the behavior of a single instance. If you need to extend the behavior of more instances either add methods to the class or include a modules behavior.