The document discusses design patterns in Ruby, highlighting their purpose and usage. It categorizes patterns into creational, structural, and behavioral, providing examples such as Builder, Factory, Singleton, Adapter, Decorator, Proxy, Command, Strategy, and Observer. The talk emphasizes the dynamic nature of Ruby and the benefits of using these patterns for efficient coding practices.

1. Design Patterns in Ruby
By Anup Biswal

2. Agenda
● Goal of the talk
● Design Patterns WHAT, WHY
● Dynamic nature of Ruby
● Various patterns with examples and use
cases

3. WHAT
General reusable solution to a commonly
occurring problem

4. WHY
mcioffeae ?????

5. Ruby is dynamic
What do you mean?

6. Quiz
Some of the patterns we always use?

7. HOW
● Creational
● Structural
● Behavioural

8. Creational
● Builder
● Factory
● Singleton

9. Builder
The purpose of the Builder Pattern is to create an abstract blueprint describing
the steps of creating an object, and then allow many different implementations
to actually carry out that process as long as they provide the necessary steps

10. Factory
The Factory Method Pattern is used for putting a layer of abstraction on top of
object creation so that directly working with its constructor is no longer
necessary. This process can lead to more expressive ways of building new
objects, and can also allow for the creation of new objects without explicitly
referencing their class.

11. Singleton
The Singleton pattern is used in situations where a single instance of a class is
all you need. Singleton objects are meant provide an effective way of organizing
global state and behavior, such as configuration data, logging support, or other
similar needs

12. Structural
● Adapter
● Decorator
● Proxy

13. Decorator
While there is a more clear distinction between a Decorator and a Proxy in
static languages, in Ruby the two concepts almost merge, except that a
Decorator is used almost exclusively for the purpose of adding / extending
behavior of a target object, and a Proxy is a more general concept

14. Adapter
An Adapter is used when you want to provide a unified interface to a number of
different objects that implement similar functionality

15. Proxy
A Proxy is any object that acts as a drop-in replacement object that does a bit of
work and then delegates to some other underlying object

16. Behavioural
● Command
● Strategy
● Observer

17. Command
The command pattern is a behavior design pattern used to store the
information necessary to call methods at a future time.

18. Strategy
The basic idea is to delegate tasks to encapsulated algorithms which are
interchangable at runtime.

19. Observer
The observer pattern is for event driven programming.
An object, called the subject, maintains a list of its dependents, called
observers, and notifies them automatically of any state changes, usually by
calling one of their methods.