The document discusses the adapter pattern in Ruby, which allows objects to bridge interfaces by modifying classes and objects at runtime. It provides examples of using an adapter to encrypt data and modify text objects to different formats. The key points covered are when to use an adapter versus modifying a class directly, with adapters preserving encapsulation but adding complexity, while modifying classes may simplify code at the cost of changing internal workings.

1. Object Oriented Imposters
The Adapter Pattern

2. Adapters in Ruby
An adapter is an object that bridges the
interface you have and the interface you need
Ruby lets us modify objects and classes
on the fly at runtime.

3. Encrypter Example

4. Implement the Encrypter Class

5. StringIOAdapter

6. Using our Adapter

7. Renderer Example

8. TextObject

9. BritishTextObject

10. BritishTextObjectAdapter

11. Modify a Class on the Fly

12. Modify a Single Instance

13. Modify a Single Instance

14. When to Adapt or Modify
When modifications are simple and clear
You understand the class you’re modifying
and the way in which it is used.
The interface mismatch is really complex.
You have no idea how the class works.

15. When to Adapt or Modify
“Adapters preserve encapsulation at the cost of
some complexity. Modifying a class may buy
you some simplification, but at the cost
tinkering with the plumbing”

16. Wrap Up
Adapters are part of the “Object Oriented
Impostor” patterns.
Not just about code, intent is critical.