Ruby Introduction

From MashupCamp

Congratulations, you have now installed Ruby on Rails. To start, let's get a feel for Ruby.

1 "Hello World"
2 "Hey World" Method
3 "Yo World" Class
4 "Yo" Program
5 Ruby Complexities
6 Ruby Reference

"Hello World"

Writing a simple Hello World program is easy in Ruby. Start a command window (Start -> Run -> "cmd"), then type "irb" to bring up interactive Ruby. Now type:

 puts "Hello World"

You will see:

 irb(main):001:0> puts "Hello World"
 Hello World
 => nil
 irb(main):002:0>

Bingo! Hello World in just one line of code!

[edit]

"Hey World" Method

Okay, that was kind-of cheating since Ruby is very interactive. Let's see how much more difficult it is to write a method to say "Hey World":

 def hey_world
   puts "Hey World"
 end
 hey_world

You will see:

 irb(main):002:0> def hey_world
 irb(main):003:1>   puts "Hey World"
 irb(main):004:1> end
 => nil
 irb(main):005:0> hey_world
 Hey World
 => nil
 irb(main):006:0>

[edit]

"Yo World" Class

That still wasn't too hard, was it? Okay, but Ruby is an object language, and so far it doesn't seem like we have been using objects. So lets do a "Yo World" program with an object:

 class YoWorld
   def say
     puts "Yo World"
   end
 end
 yo_world = YoWorld.new
 yo_world.say

You will see:

 irb(main):015:0*   class YoWorld
 irb(main):016:1>     def say
 irb(main):017:2>       puts "Yo World"
 irb(main):018:2>     end
 irb(main):019:1>   end
 => nil
 irb(main):020:0>
 irb(main):021:0*   yo_world = YoWorld.new
 => #<YoWorld:0x28aa488>
 irb(main):022:0>   yo_world.say
 Yo World
 => nil
 irb(main):023:0>

Still not very hard at all!

[edit]

"Yo" Program

Okay, that is pretty easy, but it is still not a program, right? Isn't actually writing a program instead of using interactive Ruby much more difficult? Well, not really. Copy this to "yo.rb"

 class Yo
   def say
     puts "Yo"
   end
 end
 yo = Yo.new
 yo.say

Now exit irb (type "exit" and from the command prompt type:

 ruby yo.rb

You will see:

 C:\>copy con yo.rb
 class Yo
   def say
     puts "Yo"
   end
 end
 yo = Yo.new
 yo.say
 ^Z
       1 file(s) copied.
 C:\>ruby yo.rb
 Yo
 C:\>

Writing an object-oriented program can't get much easier than that!

[edit]

Ruby Complexities

Are you asking yourself, "Is that is hard as it gets?" Well, there are some more complex parts of Ruby that exposes some very powerful functionality, but Ruby just generally makes good sense.

Here are some aspects of Ruby that have confused people: