CSCE 740 Software Engineering
Ruby and the tools
Topics


January 15, 2014
Ruby
Rails
Ruby
 http://www.ruby-doc.org/
 http://ruby.about.com/od/tutorialsontheweb/tp/10waysfr
ee.htm
 https://www.ruby-lang.org/en/documentation/quickstart/
Rails and Beyond
 http://ruby.railstutorial.org/ruby-on-rails-tutorial-book
–2–
CSCE 740 Spring 2014
The Rspec Book 2010
Latest versions
• ruby
• ruby-gems
• rspec
• rspec-rails
• cucumber
• cucumber-rails
• database_cleaner
• webrat
• selenium
• rails
–3–
CSCE 740 Spring 2014
Read Chapters 1-3 Ruby3
• http://www.ruby-doc.org/
–4–
Programming Ruby 1.9 Dave Thomas
CSCE 740 Spring 2014
Java  Ruby - Three Pillars of Ruby
1. Everything is an object.

in Java an integer needs to be boxed to act like an object.
2. Every operation is a method call on some object and
returns a value.

in Java operator overloading is different from method
overriding
3. All programming is metaprogramming.

–5–
classes can be added or changed at any time even run time
SaaS book – Fox and Patterson
CSCE 740 Spring 2014
Getting Started
 ruby –v
 ruby prog.rb
// puts “hello world\n”
 irb
// interactive ruby
 http://pragprog.com/titles/ruby3/source_code
 ri ClassName
–6–
//documentation of ClassName
Programming Ruby 1.9 Dave Thomas
CSCE 740 Spring 2014
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

–7–
puts “the absolute value of #{num} is #{pos}\n”
Prog Ruby 1.9 Dave Thomas
CSCE 740 Spring 2014
Ruby - Variable Name Conventions
 Variable Name Punctuation
 name - local variable
 $name, $NAME, - globals (never use anyway!)
 @name – instance variables
 @@name – class variables
 Name – class names and constants
–8–
Prog Ruby 1.9 Dave Thomas
CSCE 740 Spring 2014
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”
–9–
Programming Ruby 1.9 Dave Thomas
CSCE 740 Spring 2014
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
– 10 –
CSCE 740 Spring 2014
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")
– 11 –
Programming Ruby 1.9 Dave Thomas
CSCE 740 Spring 2014
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
– 12 –
CSCE 740 Spring 2014
Figure 3.1 Basic Ruby Elements
– 13 –
SaaS book – Fox and Patterson
CSCE 740 Spring 2014
List of Ruby 3 Examples
1. Getting Started – “hello, Ruby Programmer”
2. Intro –
a.
b.
c.
d.
e.
f.
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
3. Tutclasses-
– 14 –
CSCE 740 Spring 2014
google(ruby 1.9 tutorial)
• Ruby Programming Language - ruby-lang.org/
• http://www.ruby-doc.org/ (again)
• http://pragprog.com/titles/ruby3/source_code (again)
• http://pragprog.com/book/ruby3/programming-ruby1-9 “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
• http://www.ruby-doc.org/stdlib-1.9.3/
– 15 –
CSCE 740 Spring 2014
Arrays and Hashes
a = [ 1, 'cat', 3.14 ] # array with three elements
# access the first element
a[0]
»
1
»
[1, "cat", nil]
# set the third element
a[2] = nil
# dump out the array
a
– 16 –
http://ruby-doc.org/docs/ProgrammingRuby/
CSCE 740 Spring 2014
Control Structures IF
if count > 10
puts "Try again"
elsif tries == 3
puts "You lose"
else
puts "Enter a number"
end
– 17 –
// body
http://ruby-doc.org/docs/ProgrammingRuby/
CSCE 740 Spring 2014
Control Structures While
while weight < 100 and numPallets <= 30
pallet = nextPallet()
weight += pallet.weight
numPallets += 1
end
– 18 –
http://ruby-doc.org/docs/ProgrammingRuby/
CSCE 740 Spring 2014
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
– 19 –
http://ruby-doc.org/docs/ProgrammingRuby/
CSCE 740 Spring 2014
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) = {“”}
– 20 –
CSCE 740 Spring 2014
Regular Expressions Examples
• ?
– 21 –
CSCE 740 Spring 2014
Ruby Regular Expressions Examples
– 22 –
CSCE 740 Spring 2014
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'
– 23 –
http://ruby-doc.org/docs/ProgrammingRuby/
CSCE 740 Spring 2014
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, " -- "
– 24 –
http://ruby-doc.org/docs/ProgrammingRuby/
CSCE 740 Spring 2014
Blocks
5.times { print "*" }
3.upto(6) {|i| print i }
('a'..'e').each {|char| print char }
*****3456abcde
– 25 –
http://ruby-doc.org/docs/ProgrammingRuby/
CSCE 740 Spring 2014
Ruby I/O
• Already seen
•
•
•
puts
print
P
• On reading
•
•
– 26 –
Gets
Iterate over lines of file
CSCE 740 Spring 2014
while gets
if /Ruby/
print
end
end
# assigns line to $_
# matches against $_
# prints $_
ARGF.each { |line| print line if line =~ /Ruby/ }
– 27 –
http://ruby-doc.org/docs/ProgrammingRuby/
CSCE 740 Spring 2014
Classes, Objects etc.
class Song
def initialize(name, artist, duration)
@name
= name
@artist = artist
@duration = duration
end
end
s0 =Song.new
– 28 –
http://ruby-doc.org/docs/ProgrammingRuby/
CSCE 740 Spring 2014
aSong = Song.new("Bicylops", "Fleck", 260)
aSong.inspect
aSong.to_s
– 29 –
http://ruby-doc.org/docs/ProgrammingRuby/
CSCE 740 Spring 2014
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
– 30 –
http://ruby-doc.org/docs/ProgrammingRuby/
CSCE 740 Spring 2014
Accessing instance variables
class Song
def name
@name
end
def artist
@artist
end
def duration
@duration
end
end
– 31 –
http://ruby-doc.org/docs/ProgrammingRuby/
CSCE 740 Spring 2014
Class Song
attr_reader :name, :artist, :duration
…
end
– 32 –
http://ruby-doc.org/docs/ProgrammingRuby/
CSCE 740 Spring 2014
class JavaSong {
// Java code
private Duration myDuration;
public void setDuration(Duration newDuration) {
myDuration = newDuration;
}
}
class Song
attr_writer :duration
end
– 33 –
http://ruby-doc.org/docs/ProgrammingRuby/
CSCE 740 Spring 2014
class Song
@@plays = 0
def initialize(name, artist, duration)
@name = name
@artist = artist
@duration = duration
@plays = 0
end
def play
@plays += 1
@@plays += 1
"song: #@plays plays. Total #@@plays plays."
end
– 34 –
http://ruby-doc.org/docs/ProgrammingRuby/
CSCE 740 Spring 2014
Class Methods
class Example
def instMeth
# instance method
…
end
def Example.classMeth
# class method
…
end
end
– 35 –
http://ruby-doc.org/docs/ProgrammingRuby/
CSCE 740 Spring 2014
Singletons
class Logger
private_class_method :new
@@logger = nil
def Logger.create
@@logger = new unless @@logger
@@logger
end
end
Logger.create.id
Logger.create.id
– 36 –
»
»
537766930
537766930
http://ruby-doc.org/docs/ProgrammingRuby/
CSCE 740 Spring 2014
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.”
– 37 –
http://ruby-doc.org/docs/ProgrammingRuby/
CSCE 740 Spring 2014
Specifying Access
class MyClass
def method1
# default is 'public'
#...
end
protected
# subsequent methods will be 'protected'
def method2
# will be 'protected'
#...
end
private
# subsequent methods will be 'private'
def method3
# will be 'private'
#...
end
public
# subsequent methods will be 'public'
def method4
# and this will be 'public'
#...
end
CSCE 740 Spring 2014
– 38 –
end
http://ruby-doc.org/docs/ProgrammingRuby/
September 11–Arrays Intro
a = [ 3.14159, "pie", 99 ]
a.type
a[0]
a[1]
a[2]
a[3]
– 39 –
http://ruby-doc.org/docs/ProgrammingRuby/
CSCE 740 Spring 2014
Ruby 1.9 Buy the book page
http://pragprog.com/book/ruby3/programming-ruby-1-9
• 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 …
– 40 –
http://ruby-doc.org/docs/ProgrammingRuby/
CSCE 740 Spring 2014
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
– 41 –
http://rubular.com/
CSCE 740 Spring 2014
.
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
– 42 –
http://rubular.com/
CSCE 740 Spring 2014
Fig 3.3 SaaS book - All objects All
time
– 43 –
SaaS book – Fox and Patterson
CSCE 740 Spring 2014
book_in_stock
class BookInStock
attr_reader :isbn, :price
def initialize(isbn, price)
@isbn = isbn
@price = Float(price)
end
end
– 44 –
Programming Ruby 1.9 & 2.0 - Pickaxe
CSCE 740 Spring 2014
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
– 45 –
Programming Ruby 1.9 & 2.0 - Pickaxe
CSCE 740 Spring 2014
book_in_stock
class BookInStock
def initialize(isbn, price)
@isbn = isbn
@price = Float(price)
end
def to_s
"ISBN: #{@isbn}, price:
#{@price}"
end
end
– 46 –
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 & 2.0 - Pickaxe
CSCE 740 Spring 2014
book_in_stock4
def price
@price
class BookInStock
def initialize(isbn, price)
@isbn = isbn
end
# ..
end
@price = Float(price)
end
def isbn
@isbn
end
book =
BookInStock.new("isbn1",
12.34)
puts "ISBN =
#{book.isbn}"
puts "Price =
#{book.price}"
– 47 –
Programming Ruby 1.9 & 2.0 - Pickaxe
CSCE 740 Spring 2014
book_in_stock5
class BookInStock
attr_reader :isbn, :price
def initialize(isbn, price)
@isbn = isbn
@price = Float(price)
end
def price=(new_price)
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}"
@price = new_price
end
# ...
– 48 –
end
Programming Ruby 1.9 & 2.0 - Pickaxe
CSCE 740 Spring 2014
book_in_stock6
class BookInStock
attr_reader :isbn
attr_accessor :price
def initialize(isbn, price)
@isbn = isbn
@price = Float(price)
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}"
end
# ...
end
– 49 –
Programming Ruby 1.9 & 2.0 - Pickaxe
CSCE 740 Spring 2014
book_in_stock7
def price_in_cents
Integer(price*100 + 0.5)
class BookInStock
end
# ...
attr_reader :isbn
attr_accessor :price
def initialize(isbn, price)
@isbn = isbn
@price = Float(price)
end
– 50 –
end
book =
BookInStock.new("isbn1",
33.80)
puts "Price
#{book.price}"
=
puts "Price in cents =
#{book.price_in_cents}"
Programming Ruby 1.9 & 2.0 - Pickaxe
CSCE 740 Spring 2014
book_in_stock8
def price_in_cents
Integer(price*100 + 0.5)
class BookInStock
attr_reader :isbn
attr_accessor :price
end
def
price_in_cents=(cents)
@price = cents / 100.0
def initialize(isbn, price)
@isbn = isbn
@price = Float(price)
end
# ...
end
end
– 51 –
Programming Ruby 1.9 & 2.0 - Pickaxe
CSCE 740 Spring 2014
book = BookInStock.new("isbn1", 33.80)
puts "Price
= #{book.price}"
puts "Price in cents = #{book.price_in_cents}"
book.price_in_cents = 1234
– 52 –
CSCE 740 Spring 2014