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RUBY ON RAILSIntroduction to Ruby

What is Ruby?

Ruby is: from Japan

Yukihiro “Matz” Matsumoto

Ruby is: a scripting language

“Ruby is simple in appearance, but is very complex inside, just like our human body.” – Matz

Ruby is: Object Oriented

“I wanted a scripting language that was more powerful than Perl, and more object-oriented

than Python.” – Matz

5.times { print "We *love* Ruby -- it's outrageous!" }

Ruby is: Flexible

class Numeric  def plus(x)    self.+(x)  endendy = 5.plus 6# y is now equal to 11

Ruby has:Blocks

search_engines =   %w[Google Yahoo MSN].map do |engine|    "http://www." + engine.downcase + ".com"  end# search_engines = [‘http://www.google.com’, http://www.yahoo.com’, ‘http://www.msn.com’]

Ruby is:Single Inheritance

class MyArray  include Enumerableend

Ruby is:Pretty Easy to

Read

var could be a local variable.@var is an instance variable.

$var is a global variable.

What is Rails?

Rails is:A Web Application Framework

written in Ruby

What’s the advantage?

Functionality common to many web applications abstracted into a stable, tested

code base.

Rails leverages the RubyGem code packaging system to make installing and versioning

libraries of code exceedingly easy.

So why is Rails unique?

Convention Over Configuration approach to get you started quickly.

DRY principles and built-in testing to help ensure your code is lasting.

How easy is it, really?

Let’s do an example.

How is it Structured?

Model View ControllerModel=State, View=Response to User, Controller=Logic

How does that show up in Rails?

Model — ActiveRecordController—ActionController

View—ActionView

MVC in Webapps

ModelOO abstraction for RDB

Classes—TablesObjects—Rows

Queries & Operations—Class Methodsclass Client < ActiveRecord::Base has_one :address has_one :mailing_address has_many :ordersend

ViewTemplates for HTML documents

ERB—Embedded Ruby

ControllerInterface between user, model and view.

This is where you line everything up.

Let’s go back to the example

Assignment“Seems really pricey for a relatively simple

software like this. Someone write an opensource alternative? it looks like

something that can be thrown together in a weekend.”

— ktharavaad writing about Stack Overflow @ news.ycombinator.com

Rewrite Stack Overflow

Requirements: Questions, Responses, Users, VotingGo further if you feel ambitious.

Tools RequiredText editor,Terminal,

script/server,http://api.rubyonrails.org/,

http://www.ruby-doc.org/core/,http://guides.rubyonrails.org/,

script/console