rubytarball.tar.gz

Do you want to be an interpreted language geek? Are you tired of getting entangled in the dense syntaxes? Does it irritate you to compile your code to machine language first? Are you looking for an easy-to-use scripting language? Well, Ruby is the best pick for you then!

Ruby is a smart, easy-to-use, functional, Object-Oriented programming language, which comes as a wondrous mix of Perl's scripting power, Pythonic capabilities and much more! As Matsumoto, creator of Ruby, implies: "I hope to see Ruby help every programmer in the world to be productive, and to enjoy programming, and to be happy. That is the primary purpose of Ruby language."

This introductory course will be providing you with hands-on practice with the support of a bunch of interactive illustrations, exercises and the integral topics of variables, built-in classes, objects, conditionals, blocks and much more!

Cool, right? Ready to dive into one of the most influential and demanding third generation programming language? Let's tune in!

Ruby: An Amateur's Pitch

Let's start by creating a class `Calculator`, and adding some methods to it,
step by step.

In Ruby, you define a class like this:


That's all. It's not a very useful class since it's completely empty, but
it's a class.

>💡
> 
>A class is defined using the keyword <code>class</code>, a name, and the
keyword <code>end</code>.

$$$$
# Use Capital Letters to Define Classes
Also, you see that the class has the name `Calculator`, which starts with an
uppercase letter. In Ruby, this is required, and you'd get an error if you
tried to define a class `calculator`.

# `CamelCase` and `snake_case`
Also, for class names that consist of several words the Ruby community has the
convention to separate these words by uppercase letters, as in
`RubyStudyGroup`. This is called **CamelCase**, because of the humps. Whereas for
variable and method names we use underscores and keep everything lowercase:
`local_variable` and `method_name`. This is called **snake_case**.


>💡
> 
>Class names must start with an uppercase letter, and should use CamelCase.
Variable and methods names should use snake_case.


Ok, back to our class `Calculator`.

# Defining our `Calculator` Class
Since we've defined a full, valid class, we can now already use it to create a
new, concrete calculator instance, an object from it.

You can think about the instance as the concrete calculator object that you can
hold in your hands, and use to do actual calculations. The class, on the other
hand, is more like the idea or concept of a calculator, like the idea of it that
you have when you order a calculator online.

Ok, here's how to do create a new, concrete instance from our class:

```ruby
Calculator.new
```

# `new`
That's right. `new` is a method, and it is defined on the class itself (which,
as you might remember, is also an object, so it can have methods). This method
creates a new instance of the class, and returns it.

>💡
> 
>The method <code>new</code> is defined on every class, and returns a new
instance of the class.

Cool. Let's have a look at that object:

This lesson will teach you how to define your own classes in Ruby!

Defining Classes