ruby on rails 101.2. wtf? created by matz in 1993 inspired by smalltalk rubygems = cspan rake = ant...

Ruby on Rails 101.2

WTF?

• Created by Matz in 1993

• Inspired by Smalltalk

• Rubygems = CSPAN

• Rake = ant

• Rdoc = javadoc

http://rubyurl.com/D1LA

QuickTime™ and aTIFF (PackBits) decompressorare needed to see this picture.

How its like Java

• Object orientated

• Supports single inheritance

• Has exceptions

• Runs on multiple OS’s

• Runs on Java runtime (using jruby)

How it differs

• Loosely typed until assigned

• Supports closures / passing blocks

• Supports ‘modular’ design (mixins)

• Poor language level support for mulit-threaded execution

• No primitives (int, float etc)

When might you use it?

YARJC: Yet another Rails vs. Java Comparison

• Justin Gehtland recently tried re-implementing one of his web applications in Ruby on Rails instead of his normal Java Spring/Hibernate setup, according to a Slashdot post.


http://www.theserverside.com/news/thread.tss?thread_id=33120

YARJC: Yet another Rails vs. Java Comparison

• Justin Gehtland recently tried re-implementing one of his web applications in Ruby on Rails instead of his normal Java Spring/Hibernate setup, according to a Slashdot post.


http://www.theserverside.com/news/thread.tss?thread_id=33120

Convention over configuration

Setup

• http://www.rubyonrails.org/down• http://www.sqlite.org/

– The version that comes with Leopard isn't high enough. You'll need to get he source and make / sudo make install. Then run 'gem install sqlite3-ruby' (all on the mac). The binaries should do for windows.

• http://download.netbeans.org/netbeans/6.0/final/ http://subversion.tigris.org/project_packages.html

Resources

• http://groups.google.com/group/ruby_ireland/web/rails-resources

• http://railscasts.com/

• http://www.railsenvy.com/

• http://tinyurl.com/ytgp8d ;)

http://groups.google.com/group/ruby_ireland/web/rails-resources

http://groups.google.com/group/ruby_ireland/web/rails-resources

http://railscasts.com/

http://www.railsenvy.com/

http://tinyurl.com/ytgp8d

What we’ll cover

• :symbols

• Passing blocks

• Creating objects

• Closures

:symbols

“a”.intern = :a

Symbols are ‘weird string’s• Immutable (cannot be reassigned)• Used internally to represent language elements

• eg: 100 would have a symbol assocaited with it• Commonly used in hash maps as keys

Passing blocks (goal posts)

3.times do puts “Hello world”End

http://innig.net/software/ruby/closures-in-ruby.rb

myArray = Array.new [3, 4, 3, 9]myArray.each do |i|puts Iend

Sans goalpoasts

Avec goalpoasts

3.times { puts “Hello world”}


myArray = Array.new [3, 4, 3, 9]myArray.each { |i|puts i}

Sans goalpoasts

Avec goalpoasts

Hashes

myHash = { :name => “James”, :occupation => “Programmer” } myHash.each { |i, k| puts “#{i}:#{k}”}

Everything is an object

class James

initializeputs “initializing”@x = 3 # defines a member variable

end

# provides an accessordef x

@xend# set x from outisde of the def x= arg

@x = argend

endhttp://innig.net/software/ruby/closures-in-ruby.rb

class Personattr_accessor :second_nameinitialize

puts “initializing”@first_name = 3 # defines member

variable end

end


~ jkennedy$ irbirb(main):001:0> require 'test'=> trueirb(main):002:0> j = James.newinitialising=> #<James:0x1cc8e4 @x=3>irb(main):003:0> j.x=> 3irb(main):004:0> j.x= 5=> 5irb(main):005:0> j.x=> 5irb(main):006:0>

Exceptions

class RaisingExceptionionator

def initialize begin

file = open “some_file” rescue

file = STDINretry # error?

endend

end

Closures

# Example 1: def thrice yield yield yieldend

x = 5puts "value of x before: #{x}"thrice { x += 1 }puts "value of x after: #{x}"


# Example 2: local scopedef thrice_with_local_x x = 100 yield yield yield puts "value of x at end of thrice_with_local_x: #{x}"end

x = 5thrice_with_local_x { x += 1 }puts "value of outer x after: #{x}"


# Example 3: thrice do # note that {...} and do...end are equivalent y = 10 puts "Is y defined inside the block where it is first set?" puts "Yes." if defined? yendputs "Is y defined in the outer context after being set in the block?"puts "No!" unless defined? y


#Example 4: yield and scopedef six_times(&block) thrice(&block) thrice(&block)end

x = 4six_times { x += 10 }puts "value of x after: #{x}"


# Example 5# So do we have closures? Not quite! We can't hold on #to a &block and call it later at an arbitrary# time; it doesn't work. This, for example, will not #compile:## def save_block_for_later(&block)# saved = &block;# end## But we *can* pass it around if we use drop the &, and use block.call(...) instead of yield:

def save_for_later(&b) @saved = b # Note: no ampersand! This turns a block into a closure of sorts.end http://innig.net/software/ruby/closures-in-ruby.rb

# Example 5 : … continued

save_for_later { puts "Hello!" }puts "Deferred execution of a block:"@[email protected]


@saved_proc_new = Proc.new { puts "I'm declared with Proc.new." }@saved_proc = proc { puts "I'm declared with proc." }@saved_lambda = lambda { puts "I'm declared with lambda." }def some_method puts "I'm declared as a method."end@method_as_closure = method(:some_method)

puts "Here are four superficially identical forms of deferred execution:"@saved_proc_new.call@saved_proc.call@saved_lambda.call@method_as_closure.call


Modules

• Modules cannot be instantiated

• Define a set of ‘behaviours’ which an object can ‘inherit’

Module Politeness

def say_helloputs “Hello”

endend

class Ambassador

def initializerequire ‘Politeness’

end

end

kofi = Ambassador.newkofi.say_hello

Rails 2.0.2: rails myfirstproject: cd myfirstproject: rake rails:freeze:gems: script/generate - -help: script/destroy - -help

: script/migration - -help

: script/resource - -help

: script/scaffold - -help

Rails 2.0.2: rails myfirstproject: cd myfirstproject: rake rails:freeze:gems: script/generate - -help: script/destroy - -help

: script/migration - -help

: script/resource - -help

: script/scaffold - -help

Freezing railsImports the rails

Code into your app

QuickTime™ and aTIFF (LZW) decompressor

are needed to see this picture.

Sqllite

:script/generate model Person name:string phone:integer biography:text:rake db:create

:rake db:migrate:sqllite3 db/development.sqllite3sqllite>.tables

Anatomy of a project


Global configuration

Methods available in views

Active Record Classes *

Templates

Active Record Classes *

URL => controller configuration

CRUD

• Create => [ new, update]

• Read => [ list, show]

• Update => [edit, update]

• Delete => [destroy]

Create

rake rails:freeze:gems

def new@item = Item.new

end

def update@item = Item.new params[:item]if @item.save

flash[:notice] = ‘Item was created’else

render :action => “new”end

end

Read


def index@items = Item.find :all

end

def show@item = Item.find params[:id]

end

Update


def edit@item = Item.find params[:id]

end

def show@item = Item.find params[:id]

end

Delete


def edit@item = Item.find params[:id]@item.destory

end

Adding Authentication

./script/plugin install http://svn.techno-weenie.net/projects/plugins/restful_authentication/

./script/generate authenticated user sessions

ActiveRecordSession

only

Setting site template

• #{APP_ROOT}/app/views/layout/#{model_name}.erb

• <%= yield %> renders content

Get a template

• Google: ‘yui builder’

<%= stylesheet_link_tag 'application' %>

<%= javascript_include_tag :defaults %>

ruby on rails 101.2. wtf? created by matz in 1993 inspired by smalltalk rubygems = cspan rake = ant...

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