Ruby Interview Question

ruby_interview_question

## Begin!

Senior programmers won't have a problem with these, while junior programmers will usually give only half-answers.

#### What is a class?

A text-book answer: classes are a blue-print for constructing computer models for real or virtual objects... boring.

In reality: classes hold **data**, have **methods** that interact with that data, and are used to **instantiate objects**.

Like this.

```ruby
class WhatAreClasses
  def initialize
    @data = "I'm instance data of this object. Hello."
  end

  def method
    puts @data.gsub("instance", "altered")
  end
end

object = WhatAreClasses.new
object.method
 #=> I'm altered data of this object. Hello.
```

#### What is an object?

An instance of a class.  

To some, it's also the root class in ruby (Object).

Classes themselves descend from the Object root class. (Kudos to Ezra)

#### What is a module?  Can you tell me the difference between classes and modules?

Modules serve as a mechanism for **namespaces**.

```ruby
module ANamespace
  class AClass
    def initialize
      puts "Another object, coming right up!"
    end
  end
end

ANamespace::AClass.new
 #=> Another object, coming right up!
```