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

– 2 – CSCE 740 Spring 2014 Ruby   ee.htm ee.htm ee.htm  Rails and Beyond 

– 3 – CSCE 740 Spring 2014 The Rspec Book 2010 Latest versions rubyruby ruby-gemsruby-gems rspecrspec rspec-railsrspec-rails cucumbercucumber cucumber-railscucumber-rails database_cleanerdatabase_cleaner webratwebrat seleniumselenium railsrails

– 4 – CSCE 740 Spring 2014 Read Chapters 1-3 Ruby3 Programming Ruby 1.9 Dave Thomas

– 5 – 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.  classes can be added or changed at any time even run time SaaS book – Fox and Patterson

– 6 – CSCE 740 Spring 2014 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 – 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  puts “the absolute value of #{num} is #{pos}\n” Prog Ruby 1.9 Dave Thomas

– 8 – CSCE 740 Spring 2014 Ruby - Variable Name Conventions  Variable Name Punctuation  name - local variable  $name, $NAME, - globals (never use anyway!) – instance variables  – class variables  Name – class names and constants Prog Ruby 1.9 Dave Thomas

– 9 – CSCE 740 Spring 2014 Puts_examples song = 1 sam = "" def sam.play(a) "duh dum, da dum de dum..." "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 – 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

– 11 – CSCE 740 Spring 2014 Method definition def say_goodnight(name) result = "Good night, " + name result = "Good night, " + name return result return resultend # Time for bed... puts say_goodnight("John-Boy") puts say_goodnight("Mary-Ellen") Programming Ruby 1.9 Dave Thomas

– 12 – CSCE 740 Spring 2014 CSE Linux Labs 1D39 – Combination on secure site1D39 – Combination on secure site CSE home page – login with CEC credentials Computer resources/Computer labs List of Linux workstationsList of Linux workstations IP addresses – machine names Ifconfig // interface config IPv4 addr and Hardware=ethernet addrIfconfig // interface config IPv4 addr and Hardware=ethernet addr “man keyword” online unix documentation“man keyword” online unix documentation

– 13 – CSCE 740 Spring 2014 Figure 3.1 Basic Ruby Elements SaaS book – Fox and Patterson

– 14 – CSCE 740 Spring 2014 List of Ruby 3 Examples 1.Getting Started – “hello, Ruby Programmer” 2.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 3.Tutclasses-

– 15 – CSCE 740 Spring 2014 google(ruby 1.9 tutorial) Ruby Programming Language - ruby-lang.org/Ruby Programming Language - ruby-lang.org/Ruby Programming LanguageRuby Programming Language (again) (again) (again) (again) “Buy the book” pagehttp://pragprog.com/book/ruby3/programming-ruby- 1-9 “Buy the book” pagehttp://pragprog.com/book/ruby3/programming-ruby- 1-9http://pragprog.com/book/ruby3/programming-ruby- 1-9 Regular Expressions (download pdf)pdf Namespaces, Source Files, and Distribution (download pdf)pdf Ruby Library Reference Built-in Classes and Modules (download pdf of the entry for class Array)pdf Standard Library

– 16 – CSCE 740 Spring 2014 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 – CSCE 740 Spring 2014 Control Structures IF if count > 10 // body puts "Try again" elsif tries == 3 elsif tries == 3 puts "You lose" else else puts "Enter a number"end

– 18 – CSCE 740 Spring 2014 Control Structures While while weight < 100 and numPallets <= 30 while weight < 100 and numPallets <= 30 pallet = nextPallet() pallet = nextPallet() weight += pallet.weight weight += pallet.weight numPallets += 1end

– 19 – CSCE 740 Spring 2014 More control puts "Danger, Will Robinson" if radiation > 3000 while square < 1000 while square < 1000 square = square*squareend More concisely, but readability?? square = square*square while square <

– 20 – 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 | salternation denotes L(r) U L(s) rsconcatenation 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”}strings are regexpr that match themselves,L(“ab”) = {“ab”} the empty string ε is a regular expr L(ε) = {“”}the empty string ε is a regular expr L(ε) = {“”}

– 21 – CSCE 740 Spring 2014 Regular Expressions Examples ?

– 22 – CSCE 740 Spring 2014 Ruby Regular Expressions Examples

– 23 – CSCE 740 Spring 2014 Ruby Regular Expressions if line =~ /Perl|Python/ 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' line.sub(/Perl/, 'Ruby') # replace first 'Perl' with 'Ruby' line.gsub(/Python/, 'Ruby') # replace every 'Python' with 'Ruby'

– 24 – CSCE 740 Spring 2014 Blocks a = %w( ant bee cat dog elk ) # create an arraya.each { |animal| puts animal } # iterate over the contents Yield – will be discussed next time [ 'cat', 'dog', 'horse' ].each do |animal| [ 'cat', 'dog', 'horse' ].each do |animal| print animal, " -- "

– 25 – CSCE 740 Spring 2014 Blocks 5.times { print "*" }3.upto(6) {|i| print i }('a'..'e').each {|char| print char }*****3456abcde

– 26 – CSCE 740 Spring 2014 Ruby I/O Already seenAlready seen puts print P On readingOn reading Gets Iterate over lines of file

– 27 – CSCE 740 Spring 2014 while gets # assigns line to $_ while gets # assigns line to $_ if /Ruby/ # matches against $_ if /Ruby/ # matches against $_ print # prints $_ print # prints $_ endendARGF.each { |line| print line if line =~ /Ruby/ }

– 28 – CSCE 740 Spring 2014 Classes, Objects etc. class Song class Song def initialize(name, artist, duration) def initialize(name, artist, = = = = = = duration endend s0 =Song.new

– 29 – CSCE 740 Spring 2014 aSong = Song.new("Bicylops", "Fleck", 260)aSong.inspectaSong.to_s

– 30 – CSCE 740 Spring 2014 Inheritance class KaraokeSong < Song class KaraokeSong < Song def initialize(name, artist, duration, lyrics) def initialize(name, artist, duration, lyrics) super(name, artist, duration) super(name, artist, = = lyrics endEnd aSong = KaraokeSong.new("My Way", "Sinatra", 225, " And now, the...") aSong.to_s

– 31 – CSCE 740 Spring 2014 Accessing instance variables class Song def end def end def end

– 32 – CSCE 740 Spring 2014 Class Song attr_reader :name, :artist, :duration …end

– 33 – CSCE 740 Spring 2014 class JavaSong { // Java code class JavaSong { // Java code private Duration myDuration; private Duration myDuration; public void setDuration(Duration newDuration) { myDuration = newDuration; myDuration = newDuration; }} class Song class Song attr_writer :durationend

– 34 – CSCE 740 Spring 2014 class Song class Song = 0 = 0 def initialize(name, artist, duration) def initialize(name, artist, = = = = = = = = 0 end end def play def += += 1 += 1 += 1 "song: plays. Total plays." "song: plays. Total plays." end

– 35 – CSCE 740 Spring 2014 Class Methods class Example def instMeth # instance method def instMeth # instance method …end def Example.classMeth # class method def Example.classMeth # class method …endend

– 36 – CSCE 740 Spring 2014 Singletons class Logger class Logger private_class_method :new private_class_method :new = nil = nil def Logger.create def Logger.create = new unless = new unless endend Logger.create.id» Logger.create.id»

– 37 – 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.”

– 38 – CSCE 740 Spring 2014 Specifying Access class MyClass def method1 # default is 'public' def method1 # default is 'public' #... #... end protected # subsequent methods will be 'protected' protected # subsequent methods will be 'protected' def method2 # will be 'protected' def method2 # will be 'protected' #... #... end private # subsequent methods will be 'private' private # subsequent methods will be 'private' def method3 # will be 'private' def method3 # will be 'private' #... #... end public # subsequent methods will be 'public' public # subsequent methods will be 'public' def method4 # and this will be 'public' def method4 # and this will be 'public' #... #... endend

– 39 – CSCE 740 Spring 2014 September 11–Arrays Intro a = [ , "pie", 99 ]a.typea[0]a[1]a[2]a[3]

– 40 – CSCE 740 Spring 2014 Ruby 1.9 Buy the book page Regular Expressions (download pdf)Regular Expressions (download pdf)pdf Namespaces, Source Files, and Distribution (download pdf)Namespaces, Source Files, and Distribution (download pdf)pdf Built-in Classes and Modules (download pdf of the entry for class Array)Built-in Classes and Modules (download pdf of the entry for class Array)pdf Free Content …Free Content …

– 41 – CSCE 740 Spring 2014 Rubular site - Regular Expressions Rubular: a Ruby regular expression editor and tester 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 \AStart of string \zEnd of string

– 42 – CSCE 740 Spring 2014.Any single character \sAny whitespace character \SAny non-whitespace character \dAny digit \DAny non-digit \w Any word character (letter, number, underscore) \WAny non-word character \bAny 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 – CSCE 740 Spring 2014 Fig 3.3 SaaS book - All objects All time SaaS book – Fox and Patterson

– 44 – CSCE 740 Spring 2014 book_in_stock class BookInStock attr_reader :isbn, :price attr_reader :isbn, :price def initialize(isbn, price) def initialize(isbn, = = = = Float(price) end endend Programming Ruby 1.9 & Pickaxe

– 45 – 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 Programming Ruby 1.9 & Pickaxe

– 46 – CSCE 740 Spring 2014 book_in_stock class BookInStock def initialize(isbn, price) def initialize(isbn, = = = = Float(price) end end def to_s def to_s "ISBN: price: "ISBN: price: end endend 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 – CSCE 740 Spring 2014 book_in_stock4 class BookInStock def initialize(isbn, price) def initialize(isbn, = = = = Float(price) end end def isbn end end end end #.. #..end book = BookInStock.new("isbn1", 12.34) puts "ISBN = #{book.isbn}" puts "Price = #{book.price}" Programming Ruby 1.9 & Pickaxe

– 48 – CSCE 740 Spring 2014 book_in_stock5 class BookInStock attr_reader :isbn, :price attr_reader :isbn, :price def initialize(isbn, price) def initialize(isbn, = = = = Float(price) end end def price=(new_price) def = = new_price end end #... #...end 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}" Programming Ruby 1.9 & Pickaxe

– 49 – CSCE 740 Spring 2014 book_in_stock6 class BookInStock attr_reader :isbn attr_reader :isbn attr_accessor :price attr_accessor :price def initialize(isbn, price) def initialize(isbn, = = = = Float(price) end end #... #...end 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}" Programming Ruby 1.9 & Pickaxe

– 50 – CSCE 740 Spring 2014 book_in_stock7 class BookInStock attr_reader :isbn attr_reader :isbn attr_accessor :price attr_accessor :price def initialize(isbn, price) def initialize(isbn, = = = = Float(price) end end def price_in_cents Integer(price* ) Integer(price* ) end end #... #...end book = BookInStock.new("isbn1", 33.80) puts "Price = #{book.price}" puts "Price in cents = #{book.price_in_cents}" Programming Ruby 1.9 & Pickaxe

– 51 – CSCE 740 Spring 2014 book_in_stock8 class BookInStock attr_reader :isbn attr_reader :isbn attr_accessor :price attr_accessor :price def initialize(isbn, price) def initialize(isbn, = = = = Float(price) end end def price_in_cents Integer(price* ) Integer(price* ) end end def price_in_cents=(cents) def = cents / = cents / end end #... #...end Programming Ruby 1.9 & Pickaxe

– 52 – 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