Explore OOP in Ruby to gain a deeper understanding of Ruby objects, Ruby methods, and Ruby classes, enabling you to solve multiple problem sets with an object-oriented approach.

Become a Ruby Developer

Module Overview
Ruby is a smart, functional, and object-oriented programming language that blends the best features of scripting power with user-friendly syntax. In this module, we’ll dive into OOP in Ruby with hands-on practice using interactive exercises and illustrations. We'll start by creating and managing Ruby objects. Next, we’ll explore Ruby methods and blocks, essential tools in Ruby programming. Finally, we'll delve into Ruby classes and how they are used to implement OOP principles.

Ruby OOP (Object-Oriented Programming)

# Asking an object for information

Remember that people have the ability to remember their name, and tell it, when asked.

We’ve already implemented the first part of this. Our `Person` instance now knows her name, `“Ada”`.

Let’s look at the second part. Remember also that methods are either questions or commands. We want to add a method that answers the question, What’s your name?

It’s as simple as this:

class Person
  def initialize(name)
    @name = name
  end

  def name
    @name
  end
end

Before we discuss what this does, let’s look at how we can use our new method. We can now call the method on the `person` object, like this:

person = Person.new("Ada")
puts person.name

This prints the name, `Ada`, and that’s what we want. We can create a new `person` object, passing a name to it. Once that person is created, we’re able to ask for its name, and we’ll get the name back.

# Explanation

Let’s look at how this works internally:

* In the first line, the object assigned to the `person` variable is an initialized new instance of the `Person` class. Initialized means that the `initialize` method has already been called and has already assigned the `"Ada"` string to the `@name` instance variable.

* Now, this `person` object has the `name` method, as defined in the class definition of `Person` above. In the second line, we call this method, `person.name`.

* When the `name` method is called, it does nothing else but evaluate the `@name` instance variable from the object scope. Because this has previously been set to `"Ada"`, it returns this string. Because this is the last line in the `name` method, the method also returns this string.

* For that reason, the `person.name` method call returns the `"Ada"` string, which is then passed to `puts`, which prints it out.

# What are attribute readers?

Methods that do nothing else but return a value assigned to an instance variable with the same name, called **attribute readers**, are very common.

By attribute, the Ruby community means an instance variable, so an attribute reader is a method that reads an instance variable.

> **Remember:** An attribute reader returns the value of an instance variable.

Another way of looking at this is that an attribute reader is a method that exposes an instance variable. That is, it makes it accessible for others. It allows us to ask for the value of an instance variable with the same name and does nothing but return its value. Once defined, others can ask this object for knowledge that otherwise would be private and inaccessible.

In our case, the `name` attribute reader exposes the `@name` instance variable so others can ask for it.

> **Remember:** An attribute reader exposes an instance variable.

It’s unclear why “attribute” was the chosen term. It would be much less confusing to use the term “instance variable reader” instead. Maybe the simple reason is that programmers don’t like to type more than necessary, and this saves eight characters. Who knows?

This lesson explains attribute readers and how they’re related to instance variables.

Objects

Blocks

Conditionals

Writing Classes

Mini project 1

Conclusion

Attribute Readers

Asking an object for information