1. 6 - Ruby in the Rough 7 - Ruby on Rails 03/03/2006 Taylan Yemliha
Beyond Java
6 - Ruby in the Rough 7 - Ruby on Rails 03/03/ Taylan Yemliha

2. Ruby
Dynamic
Fully object-oriented
Interpreted
03/03/2006

3. OO Everything is an object (ints, strings, etc.) irb(main):002:0> 7
=> 7
irb(main):003:0> 7.class
Fixnum
irb(main):011:0> 7.5.round
=> 8
irb(main):012:0> nil.class
=> NilClass
03/03/2006

4. Typing Dynamically typed irb(main):013:0> n=1 => 1
irb(main):014:0> n.class
=> Fixnum
irb(main):015:0> n="bbs"
=> "bbs"
irb(main):016:0> n.class
=> String
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5. Typing Strongly typed irb(main):017:0> n+3
TypeError: cannot convert Fixnum into String
from (irb):17:in `+'
from (irb):17
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6. Conditionals irb(main):020:0> def silence?(b)
irb(main):021:1> puts "aaaa" if b
irb(main):022:1> end
=> nil
irb(main):023:0> silence? true
aaaa
irb(main):025:0> silence? false
irb(main):026:0> silence? 0
irb(main):028:0> silence? nil
03/03/2006

7. Looping irb(main):030:0> puts line while line = gets "aaa" one two
three ^Z
=> nil
03/03/2006

8. Ranges irb(main):031:0> range = 1..3 => 1..3
irb(main):032:0> range.class
=> Range
irb(main):033:0> ('a'..'z')==='h'
=> true
irb(main):034:0> ('a'..'z')==='H'
=> false
irb(main):035:0> (1..10) === 5
03/03/2006

9. Ranges irb(main):036:0> for c in 'g'.. 'j'
irb(main):037:1> print c + '-'
irb(main):038:1> end
g-h-i-j-=> "g".."j"
irb(main):039:0> for c in 'g'.. 'j'
irb(main):040:1> puts c
irb(main):041:1> end g h i j
=> "g".."j"
03/03/2006

10. Regular Expressions irb(main):042:0> regex = /better/
irb(main):043:0> regex.class
=> Regexp
irb(main):044:0> "Mine is bigger" =~ regex
=> nil
irb(main):045:0> "Mine is better" =~ regex
=> 8
03/03/2006

11. Containers - Hashes
irb(main):046:0> numbers={0=>"zero", 1=>"one", 2=>"two", 3=>"three"}
=> {0=>"zero", 1=>"one", 2=>"two", 3=>"three"}
irb(main):047:0> 4.times {|i| puts numbers[i]}
zero
one
two
three
=> 4
03/03/2006

12. Containers - Arrays irb(main):048:0> stack = [1,2,3]
=> [1, 2, 3]
irb(main):049:0> stack.push "cat"
=> [1, 2, 3, "cat"]
irb(main):050:0> stack.pop
=> "cat"
irb(main):051:0> stack
03/03/2006

13. Files A simple GREP ruby grep.rb filename regex
File.open(ARGV[0]) do |file|
rx = Regexp.new(ARGV[1])
while line=file.gets
puts line if line =~ rx
end
ruby grep.rb filename regex
03/03/2006

14. Applying Some Structure
Inside-out Refactoring
Group common code in libraries
Call them in your methods
Outside in refactoring
Your methods can
take code-blocks as parameters
call them
even pass parameters to them
03/03/2006

15. Outside-in Refactoring
def threeTimes
  yield
end
threeTimes { puts "Hello" }
produces:
Hello
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16. Classes calculator.rb class Calculator def initialize @total = 0 end
def add(x)
@total += x
def subtract(x)
@total -= x
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17. Classes irb(main):001:0> require calculator
NameError: undefined local variable or method `calculator' for main:Object
from (irb):1
irb(main):002:0> require 'Calculator'
=> true
irb(main):003:0> c = Calculator.new
=>
irb(main):004:0> c.add 100
=> 100
irb(main):005:0> c.subtract 40
=> 60
03/03/2006

18. Classes irb(main):006:0> class Calculator
irb(main):007:1> def reset
= 0
irb(main):009:2> end
irb(main):010:1> end
=> nil
irb(main):011:0> c.reset
=> 0
03/03/2006

19. Classes irb(main):012:0> class IrsCalculator < Calculator
irb(main):013:1> def add(x)
irb(main):014:2> x = x/2 if x>0
irb(main):015:2> super
irb(main):016:2> end
irb(main):017:1> end
=> nil
irb(main):018:0> c = IrsCalculator.new
=>
irb(main):019:0> c.add 100
=> 50
03/03/2006

20. Classes irb(main):020:0> Class.superclass => Module
irb(main):021:0> Module.superclass
=> Object
irb(main):022:0> Object.superclass
=> nil
03/03/2006

21. Mixins Interfaces with implementation
Can access the including class’s methods
Partly adds the benefit of multi-inheritance
Implemented using Modules
03/03/2006

22. Interceptors You can rename methods on-the-fly class Class
alias_method :orig_new, :new
def new(*args)
result = orig_new(*args)
print “Unattended laptop error! ”
#puts result
return result
end
03/03/2006

23. Interceptors irb(main):001:0> require "Class" => true
irb(main):002:0> a=[1,2,3]
#<RubyToken::TkIDENTIFIER:0x2941d40>
#<RubyToken::TkASSIGN:0x2941b48>
#<RubyToken::TkLBRACK:0x >
#<RubyToken::TkINTEGER:0x29416c8>
#<RubyToken::TkCOMMA:0x29414d0>
#<RubyToken::TkINTEGER:0x >
#<RubyToken::TkCOMMA:0x29410b0>
#<RubyToken::TkINTEGER:0x2940e70>
#<RubyToken::TkRBRACK:0x2940c60>
#<RubyToken::TkNL:0x >
=> [1, 2, 3]
03/03/2006

24. Ruby On Rails
What is it?
“Rails is a full-stack, open-source web framework in Ruby for writing real-world applications with joy and less code than most frameworks spend doing XML sit-ups” David H. Hansson
03/03/2006

25. Some Numbers
The author’s test case gives shows impressively superior numbers for Rails over Java/Spring/Hibernate solution in development time/code size as well as performance in most cases.
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26. Architecture
03/03/2006

27. Under the Hood
Active Record It’s a wrapper around a db table, with domain logic built into the wrapper. You can also do inheritance and manage relationships.
Action Pack Splits the request into a controller part and a view part.
03/03/2006

28. Showcases RubyBB by Russ Smith http://rubybb.readbim.com/
384 Lines of Code
StoryCards Web app to support XP style dev. by Jim Weirich
1,250 Lines of code 8 hours of development time
Basecamp: A commercial Rails web-app with over 10,000 users.
“Web-based project management”
Launched after 4,000 Lines of Code.
2 man-months of months of programming by a single developer
03/03/2006