1. CSCE 740 Software Engineering
Ruby and the tools
Topics
Ruby
Rails
January 15, 2014

2. Ruby
Rails and Beyond

3. The Rspec Book 2010 Latest versions ruby ruby-gems rspec rspec-rails
cucumber
cucumber-rails
database_cleaner
webrat
selenium
rails

4. Programming Ruby 1.9 Dave Thomas
Read Chapters 1-3 Ruby3
Programming Ruby 1.9 Dave Thomas

5. Java  Ruby - Three Pillars of Ruby
Everything is an object.
in Java an integer needs to be boxed to act like an object.
Every operation is a method call on some object and returns a value.
in Java operator overloading is different from method overriding
All programming is metaprogramming.
classes can be added or changed at any time even run time
SaaS book – Fox and Patterson

6. Programming Ruby 1.9 Dave Thomas
Getting Started
ruby –v
ruby prog.rb // puts “hello world\n”
irb // interactive ruby
ri ClassName //documentation of ClassName
Programming Ruby 1.9 Dave Thomas

7. Ruby is Really Object Oriented
Really Object Oriented – everything is an object
For Java you might use
pos = Math.abs(num)
In Ruby
num = -123
pos = num.abs
Variables inside literal strings #{ … } notation
puts “the absolute value of #{num} is #{pos}\n”
Prog Ruby 1.9 Dave Thomas

8. Ruby - Variable Name Conventions
Variable Name Punctuation
name - local variable
$name, $NAME, - globals (never use anyway!)
@name – instance variables
– class variables
Name – class names and constants
Prog Ruby 1.9 Dave Thomas

9. Programming Ruby 1.9 Dave Thomas
Puts_examples
song = 1
sam = ""
def sam.play(a)
"duh dum, da dum de dum ..."
end
puts "gin joint".length
puts "Rick".index("c")
puts 42.even?
puts sam.play(song)
print “string with no newline”
Programming Ruby 1.9 Dave Thomas

10. Symbols
:rhubarb - is an immutable string whose value is value is itself, well without the colon :rhubarb.to_s yields “rhubarb” “rhubarb”.to_sym yields :rhubarb not a string – string operations cannot be performed on it

11. Programming Ruby 1.9 Dave Thomas
Method definition
def say_goodnight(name)
result = "Good night, " + name
return result
end
# Time for bed...
puts say_goodnight("John-Boy")
puts say_goodnight("Mary-Ellen")
Programming Ruby 1.9 Dave Thomas

12. CSE Linux Labs 1D39 – Combination on secure site
CSE home page – login with CEC credentials
Computer resources/Computer labs
List of Linux workstations
IP addresses – machine names
Ifconfig // interface config IPv4 addr and Hardware=ethernet addr
“man keyword” online unix documentation

13. Figure 3.1 Basic Ruby Elements
SaaS book – Fox and Patterson

14. List of Ruby 3 Examples Getting Started – “hello, Ruby Programmer”
Intro –
Hello1 – def say_goodnight
Puts examples
Cmd_line – command line args passed into ruby program
“arrays” – non-homogeneous
hash_with_symbol_keys_19.rb –
Weekdays – control structures – if-elseif-else example
Tutclasses-

15. google(ruby 1.9 tutorial)
Ruby Programming Language - ruby-lang.org/
(again)
(again)
“Buy the book” page
Regular Expressions (download pdf)
Namespaces, Source Files, and Distribution (download pdf)
Ruby Library Reference
Built-in Classes and Modules (download pdf of the entry for class Array)
Standard Library

16. Arrays and Hashes a = [ 1, 'cat', 3.14 ] # array with three elements
# access the first element
a[0] 1
# set the third element
a[2] = nil
# dump out the array a
[1, "cat", nil]

17. Control Structures IF if count > 10 // body puts "Try again"
elsif tries == 3   
puts "You lose"
else   
puts "Enter a number"
end

18. Control Structures While
while weight < 100 and numPallets <= 30   
pallet = nextPallet()   
weight += pallet.weight   
numPallets += 1
end

19. More control puts "Danger, Will Robinson" if radiation > 3000
while square < 1000    
square = square*square
end
More concisely, but readability??
square = square*square  while square < 1000

20. Regular Expressions
Regular expressions are expressions that specify collections of strings (formally languages)
Main operators: Assume r and s are regular expressions then so are:
r | s alternation denotes L(r) U L(s)
rs concatenation which denotes L(r) L(s)
r* Kleene closure zero or more occurrences of strings from L(r) concatenated
Base regular expressions
strings are regexpr that match themselves,L(“ab”) = {“ab”}
the empty string ε is a regular expr L(ε) = {“”}

21. Regular Expressions Examples?

22. Ruby Regular Expressions Examples

23. Ruby Regular Expressions
if line =~ /Perl|Python/   
puts "Scripting language mentioned: #{line}”
end
line.sub(/Perl/, 'Ruby')    # replace first 'Perl' with 'Ruby' line.gsub(/Python/, 'Ruby') # replace every 'Python' with 'Ruby'  

24. Blocks a = %w( ant bee cat dog elk ) # create an array
a.each { |animal| puts animal }  # iterate over the contents
Yield – will be discussed next time
[ 'cat', 'dog', 'horse' ].each do |animal|   
print animal, " -- "

25. Blocks 5.times { print "*" } 3.upto(6) {|i| print i }
('a'..'e').each {|char| print char }
*****3456abcde

26. Ruby I/O Already seen On reading puts print P Gets
Iterate over lines of file

27. while gets # assigns line to $_ if /Ruby/ # matches against $_
print             # prints $_   
end
ARGF.each { |line|  print line  if line =~ /Ruby/ }

28. Classes, Objects etc. class Song
def initialize(name, artist, duration)     
@name     = name     
@artist   = artist     
@duration = duration   
end
s0 =Song.new

29. aSong = Song.new("Bicylops", "Fleck", 260) aSong.inspect aSong.to_s

30. Inheritance class KaraokeSong < Song
def initialize(name, artist, duration, lyrics)     
super(name, artist, duration)     
@lyrics = lyrics   
end
End
aSong = KaraokeSong.new("My Way", "Sinatra", 225, "And now, the...")
aSong.to_s

31. Accessing instance variables
class Song
  def name
  end
  def artist
  def duration
end

32. attr_reader :name, :artist, :duration … end
Class Song
attr_reader :name, :artist, :duration …
end

33. class JavaSong { // Java code private Duration myDuration;
public void setDuration(Duration newDuration) {
    myDuration = newDuration;    }
class Song   
attr_writer :duration
end

34. def initialize(name, artist, duration) @name = name @artist = artist
class Song      
def initialize(name, artist, duration)     
@name     = name     
@artist   = artist     
@duration = duration     
@plays    = 0   
end   
def play     
@plays += 1     
       
end

35. Class Methods class Example def instMeth # instance method … end
   def Example.classMeth      # class method   

36. Singletons class Logger private_class_method :new @@logger = nil
def Logger.create     
       
end
Logger.create.id

37. Access Control
“Public methods can be called by anyone---there is no access control. Methods are public by default (except for initialize, which is always private).
Protected methods can be invoked only by objects of the defining class and its subclasses. Access is kept within the family.
Private methods cannot be called with an explicit receiver. Because you cannot specify an object when using them, private methods can be called only in the defining class and by direct descendents within that same object.”

38. Specifying Access class MyClass def method1 # default is 'public' #...
#...       
end
  protected       # subsequent methods will be 'protected'
      def method2     # will be 'protected'         
  private             # subsequent methods will be 'private'
      def method3     # will be 'private'         
  public              # subsequent methods will be 'public'
      def method4     # and this will be 'public'         

39. September 11–Arrays Intro
a = [  , "pie", 99 ]
a.type
a[0]
a[1]
a[2]
a[3]

40. Ruby 1.9 Buy the book page
Regular Expressions (download pdf)
Namespaces, Source Files, and Distribution (download pdf)
Built-in Classes and Modules (download pdf of the entry for class Array)
Free Content …

41. Rubular site - Regular Expressions
Rubular: a Ruby regular expression editor and tester
[abc]
A single character of: a, b or c
[^abc]
Any single character except: a, b, or c
[a-z]
Any single character in the range a-z
[a-zA-Z]
Any single character in the range a-z or A-Z ^
Start of line $
End of line \A
Start of string \z
End of string

42. .
Any single character \s
Any whitespace character \S
Any non-whitespace character \d
Any digit \D
Any non-digit \w
Any word character (letter, number, underscore) \W
Any non-word character \b
Any word boundary
(...)
Capture everything enclosed
(a|b)
a or b a?
Zero or one of a a*
Zero or more of a a+
One or more of a
a{3}
Exactly 3 of a
a{3,}
3 or more of a
a{3,6}
Between 3 and 6 of a

43. Fig 3.3 SaaS book - All objects All time
SaaS book – Fox and Patterson

44. Programming Ruby 1.9 & 2.0 - Pickaxe
book_in_stock
class BookInStock attr_reader :isbn, :price def initialize(isbn, = = Float(price) end
Programming Ruby 1.9 & Pickaxe

45. Programming Ruby 1.9 & 2.0 - Pickaxe
book_in_stock
b1 = BookInStock.new("isbn1", 3) puts b1 b2 = BookInStock.new("isbn2", 3.14) puts b2 b3 = BookInStock.new("isbn3", "5.67") puts b3
Programming Ruby 1.9 & Pickaxe

46. Programming Ruby 1.9 & 2.0 - Pickaxe
book_in_stock
class BookInStock def initialize(isbn, = = Float(price) end def to_s "ISBN: price:
b1 = BookInStock.new("isbn1", 3) puts b1 b2 = BookInStock.new("isbn2", 3.14) puts b2 b3 = BookInStock.new("isbn3", "5.67") puts b3
Programming Ruby 1.9 & Pickaxe

47. Programming Ruby 1.9 & 2.0 - Pickaxe
book_in_stock4
def end # .. book = BookInStock.new("isbn1", 12.34) puts "ISBN = #{book.isbn}" puts "Price = #{book.price}"
class BookInStock def initialize(isbn, = = Float(price) end def
Programming Ruby 1.9 & Pickaxe

48. Programming Ruby 1.9 & 2.0 - Pickaxe
book_in_stock5
book = BookInStock.new("isbn1", 33.80) puts "ISBN = #{book.isbn}" puts "Price = #{book.price}" book.price = book.price * 0.75 # discount price puts "New price = #{book.price}"
class BookInStock attr_reader :isbn, :price def initialize(isbn, = = Float(price) end def = new_price # ...
Programming Ruby 1.9 & Pickaxe

49. Programming Ruby 1.9 & 2.0 - Pickaxe
book_in_stock6
book = BookInStock.new("isbn1", 33.80) puts "ISBN = #{book.isbn}" puts "Price = #{book.price}" book.price = book.price * 0.75 # discount price puts "New price = #{book.price}"
class BookInStock attr_reader :isbn attr_accessor :price def initialize(isbn, = = Float(price) end # ...
Programming Ruby 1.9 & Pickaxe

50. Programming Ruby 1.9 & 2.0 - Pickaxe
book_in_stock7
def price_in_cents Integer(price* ) end # ... book = BookInStock.new("isbn1", 33.80) puts "Price = #{book.price}" puts "Price in cents = #{book.price_in_cents}"
class BookInStock attr_reader :isbn attr_accessor :price def initialize(isbn, = = Float(price) end
Programming Ruby 1.9 & Pickaxe

51. Programming Ruby 1.9 & 2.0 - Pickaxe
book_in_stock8
def price_in_cents Integer(price* ) end def = cents / # ...
class BookInStock attr_reader :isbn attr_accessor :price def initialize(isbn, = = Float(price) end
Programming Ruby 1.9 & Pickaxe

52. book = BookInStock. new("isbn1", 33. 80) puts "Price = #{book
book = BookInStock.new("isbn1", 33.80) puts "Price = #{book.price}" puts "Price in cents = #{book.price_in_cents}" book.price_in_cents = 1234