Intro Ruby Classes Part I
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This document provides an overview of classes and objects in Ruby from Juan Leal, a Rubyist and Rails developer. It defines what classes and objects are, how they relate, and some basics of defining classes in Ruby. It discusses how everything in Ruby is an object, including classes, and how Class is both a class and object since it is an instance of itself. The document provides examples of defining classes, inheritance, and using the Class class to subclass.
Intro Ruby Classes Part I
- 1. Who am I ● Juan Leal – Rubyist and Rails Developer since 2007 – Worked at Equifax and Pragmatic Programmers – Currently employed at Hiplogiq
- 2. What We'll Cover ● A review of Classes and Objects ● Some basics of classes in Ruby ● ● Some background info regarding classes in Ruby. Using Ruby's class Class.
- 3. A review of Classes and Objects
- 4. What's a class? - let's review ● ● blueprint or pattern for how we want to construct something. template defining the methods and variables in a particular kind of object.
- 5. Classes vs Objects ● ● ● It's important distinguish between the two. Classes are instantiated into instances or objects. Objects and classes are not the same.
- 6. A real world analogy for example is that a blueprint of a house would a class and actual house would be an object. Class Object
- 7. Classes in Ruby, some basics
- 8. Defining a class Here we define a class and a method.
- 9. Inheritance Here the class Bar inherits from class Foo.
- 10. Define a Constructor In Ruby one defines a constructor through the method initialize. Here we've defined initialize and have it take an argument called 'name'. Then we set an instance variable to value of 'name'.
- 11. Ruby classes, some background information.
- 12. General points ● In Ruby everything is object. ● Objects are instances of a class. ● Simple right?
- 13. Lets Look at Some Code This is how we discover an object's class. This is how we discover a class' parent class.
- 14. Classes in Ruby In Ruby everything is an object. This includes classes. As such a class in Ruby is an instance of class Class. But wait, if everything is an object then that means Class is an object too. And sure enough it is. So if Class is an object, what is it an instance of? It's an instance of class Class. In other words, it's an instance of itself.
- 16. So... an instance of class Class Class is an object. Remember in Ruby everything is an object. Class is an instance of class Class. Remember all objects are instances of a class. So the thing is, there really is nothing overly significant about this. This relationships is just a result of the way the Ruby object model was designed. It won't be on the final but it's stuff that can be useful to know.
- 18. The class Class Let's take a look at what we can do with Class. We can define classes. We can do inheritance.
- 19. How I commonly use class Class Many times when people need to do a simple subclass they jam their code on a single line as shown in line :2. It's valid ruby code but a little unsightly. It resorts to using the semicolon which separates the commands. My personal preference is to subclass using class Class.
- 20. In Closing ● ● There's quite a bit about classes which we have not covered. This will be an ongoing series so keep an eye out for more to come. ● Thank you for attending. ● Twitter: @terminalbreaker
- 21. The End.