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Ruby for C# Developers

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This is an old presentation from a 2006 St Louis .NET Code Camp on Ruby for C# / .NET Developers by Cory Foy

This is an old presentation from a 2006 St Louis .NET Code Camp on Ruby for C# / .NET Developers by Cory Foy

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  • 1. Ruby for C# Developers St. Louis Code Camp May 6th, 2006 Cory Foy http://www.cornetdesign.comSt. Louis Code Camp Ruby for C# Developers Cory Foy May 6th, 2006 http://www.cornetdesign.com
  • 2. Overview • What is Ruby? • Ruby Basics • Advanced Ruby • Ruby and .NET integration • Wrap-upSt. Louis Code Camp Ruby for C# Developers Cory Foy May 6th, 2006 http://www.cornetdesign.com
  • 3. What is Ruby? • First released in 1995 by Yukihiro Matsumoto (Matz) • Object-Oriented – number = 1.abs #instead of Math.abs(1) • Dynamically Typed – result = 1+3St. Louis Code Camp Ruby for C# Developers Cory Foy May 6th, 2006 http://www.cornetdesign.com
  • 4. What is Ruby? class Person attr_accessor :name, :age # attributes we can set and retrieve def initialize(name, age) # constructor method @name = name # store name and age for later retrieval @age = age.to_i # (store age as integer) end def inspect # This method retrieves saved values "#@name (#@age)" # in a readable format end end p1 = Person.new(elmo, 4) # elmo is the name, 4 is the age puts p1.inspect # prints “elmo (4)” • http://www.rubygarden.org/faq/entry/show/3St. Louis Code Camp Ruby for C# Developers Cory Foy May 6th, 2006 http://www.cornetdesign.com
  • 5. Will It Change Your Life? • Yes! • Ok, Maybe • It’s fun to program with • And what is programming if it isn’t fun?St. Louis Code Camp Ruby for C# Developers Cory Foy May 6th, 2006 http://www.cornetdesign.com
  • 6. Ruby Basics • Variables, Classes and Methods • Properties / Attributes • Exceptions • Access Control • Importing Files and Libraries • Duck TypingSt. Louis Code Camp Ruby for C# Developers Cory Foy May 6th, 2006 http://www.cornetdesign.com
  • 7. Ruby Basics - Variables • Local (lowercase, underscores) – fred_j = Person.new(“Fred”) • Instance (@ sign with lowercase) – @name = name • Class (@@ with lowercase) – @@error_email = “testing@test.com” • Constant (Starts with uppercase) – MY_PI = 3.14 – class Move • Global ($ with name) – $MEANING_OF_LIFE = 42St. Louis Code Camp Ruby for C# Developers Cory Foy May 6th, 2006 http://www.cornetdesign.com
  • 8. Ruby Basics - Classes class Move attr_accessor :up, :right def initialize(up, right) @up = up @right = right end end • Class definitions are started with class,are named with a CamelCase name, and ended with endSt. Louis Code Camp Ruby for C# Developers Cory Foy May 6th, 2006 http://www.cornetdesign.com
  • 9. Ruby Basics - Classes class Move attr_accessor :up, :right def initialize(up, right) @up = up @right = right end end • Attributes and fields normally go at the beginning of the class definitionSt. Louis Code Camp Ruby for C# Developers Cory Foy May 6th, 2006 http://www.cornetdesign.com
  • 10. Ruby Basics - Classes class Move attr_accessor :up, :right def initialize(up, right) @up = up @right = right end end • initialize is the same concept as a constructor from .NET or Java, and is called when someone invokes your object using Move.new to set up the object’s stateSt. Louis Code Camp Ruby for C# Developers Cory Foy May 6th, 2006 http://www.cornetdesign.com
  • 11. Ruby Basics - Methods class Move def up @up end def right return @right end end • Methods return the last expression evaluated. You can also explicitly return from methodsSt. Louis Code Camp Ruby for C# Developers Cory Foy May 6th, 2006 http://www.cornetdesign.com
  • 12. Ruby Basics - Methods class Move def initialize(up, right) @up = up @right = right end end • Methods can take in specified parameters, and also parameter lists (using special notation)St. Louis Code Camp Ruby for C# Developers Cory Foy May 6th, 2006 http://www.cornetdesign.com
  • 13. Ruby Basics - Methods class Move def self.create return Move.new end def Move.logger return @@logger end end • Class (“Static”) methods start with either self. or Class.St. Louis Code Camp Ruby for C# Developers Cory Foy May 6th, 2006 http://www.cornetdesign.com
  • 14. Ruby Basics - Properties • Like .NET, Ruby supports the concept of Properties (called Attributes) class Move class Move def up def up=(val) @up @up = val end end end end move = Move.new move.up = 15 puts move.up #15St. Louis Code Camp Ruby for C# Developers Cory Foy May 6th, 2006 http://www.cornetdesign.com
  • 15. Ruby Basics - Properties • Unlike .NET, Ruby provides convenience methods for doing this class Move attr_accessor :up #Same thing as last slide end move = Move.new move.up = 15 puts move.up #15St. Louis Code Camp Ruby for C# Developers Cory Foy May 6th, 2006 http://www.cornetdesign.com
  • 16. Ruby Basics - Properties • You can specify read or write only attributes as well class Move attr_reader :up #Can’t write attr_writer :down #Can’t read end move = Move.new move.up = 15 #error d = move.down #errorSt. Louis Code Camp Ruby for C# Developers Cory Foy May 6th, 2006 http://www.cornetdesign.com
  • 17. Ruby Basics - Exceptions • Ruby has an Exception hierarchy • Exceptions can be caught, raised and handled • You can also easily retry a block of code when you encounter an exceptionSt. Louis Code Camp Ruby for C# Developers Cory Foy May 6th, 2006 http://www.cornetdesign.com
  • 18. Ruby Basics - Exceptions process_file = File.open(“testfile.csv”) begin #put exceptional code in begin/end block #...process file rescue IOError => io_error puts “IOException occurred. Retrying.” retry #starts block over from begin rescue => other_error puts “Bad stuff happened: “ + other_error else #happens if no exceptions occur puts “No errors in processing. Yippee!” ensure # similar to finally in .NET/Java process_file.close unless process_file.nil? endSt. Louis Code Camp Ruby for C# Developers Cory Foy May 6th, 2006 http://www.cornetdesign.com
  • 19. Ruby Basics – Access Control • Ruby supports Public, Protected and Private methods • Private methods can only be accessed from the instance of the object, not from any other object, even those of the same class as the instanceSt. Louis Code Camp Ruby for C# Developers Cory Foy May 6th, 2006 http://www.cornetdesign.com
  • 20. Ruby Basics – Access Control • Access is controlled by using keywords class Move private def calculate_move end #Any subsequent methods will be private until.. public def show_move end #Any subsequent methods will now be public endSt. Louis Code Camp Ruby for C# Developers Cory Foy May 6th, 2006 http://www.cornetdesign.com
  • 21. Ruby Basics – Access Control • Methods can also be passed as args class Move def calculate_move end def show_move end public :show_move protected :calculate_move endSt. Louis Code Camp Ruby for C# Developers Cory Foy May 6th, 2006 http://www.cornetdesign.com
  • 22. Ruby Basics - Imports • To use a class from another file in your class, you must tell your source file where to find the class you want to use require ‘calculator’ class Move def calculate_move return @up * Calculator::MIN_MOVE end endSt. Louis Code Camp Ruby for C# Developers Cory Foy May 6th, 2006 http://www.cornetdesign.com
  • 23. Ruby Basics - Imports • There are two types of imports – require • Only loads the file once – load • Loads the file every time the method is executed • Both accept relative and absolute paths, and will search the current load path for the fileSt. Louis Code Camp Ruby for C# Developers Cory Foy May 6th, 2006 http://www.cornetdesign.com
  • 24. Ruby Basics – Duck Typing • What defines an object? • How can you tell a car is a car? – By model? – By name? • Or, by it’s behavior?St. Louis Code Camp Ruby for C# Developers Cory Foy May 6th, 2006 http://www.cornetdesign.com
  • 25. Ruby Basics – Duck Typing class CarWash def accept_customer(car) • How would we end validate this end in .NET or Java? • We’d use static typing! So only the valid object could be passed in • What if my object has the same behavior as a Car?St. Louis Code Camp Ruby for C# Developers Cory Foy May 6th, 2006 http://www.cornetdesign.com
  • 26. Ruby Basics – Duck Typing • What is this?St. Louis Code Camp Ruby for C# Developers Cory Foy May 6th, 2006 http://www.cornetdesign.com
  • 27. Ruby Basics – Duck Typing • How about this?St. Louis Code Camp Ruby for C# Developers Cory Foy May 6th, 2006 http://www.cornetdesign.com
  • 28. Ruby Basics – Duck Typing • What about this?St. Louis Code Camp Ruby for C# Developers Cory Foy May 6th, 2006 http://www.cornetdesign.com
  • 29. Ruby Basics – Duck Typing • We know objects based on the behaviors and attributes the object possesses • This means if the object passed in can act like the object we want, that should be good enough for us!St. Louis Code Camp Ruby for C# Developers Cory Foy May 6th, 2006 http://www.cornetdesign.com
  • 30. Ruby Basics – Duck Typing Class CarWash def accept_customer(car) if car.respond_to?(:drive_to) @car = car wash_car else reject_customer end end end • Or we could just let it fail as a runtime errorSt. Louis Code Camp Ruby for C# Developers Cory Foy May 6th, 2006 http://www.cornetdesign.com
  • 31. Ruby Basics – Unit Tests • In a static-typed language, how do we use the compiler? – Find misspellings – Find improper usage – Enforce contracts – Find missing semicolonsSt. Louis Code Camp Ruby for C# Developers Cory Foy May 6th, 2006 http://www.cornetdesign.com
  • 32. Ruby Basics – Unit Tests • What is a Unit Test? • “In computer programming, a unit test is a procedure used to validate that a particular module of source code is working properly.” (Wikipedia) • Sounds like our compiler is just a unit testing mechanism!St. Louis Code Camp Ruby for C# Developers Cory Foy May 6th, 2006 http://www.cornetdesign.com
  • 33. Ruby Basics – Unit Tests • Ruby comes built in with a Unit Testing framework – Test::Unit – Create individual tests – Create test suites – Invoke our tests and suites • Using this framework and Test-Driven Development, we can have a high confidence level in our codeSt. Louis Code Camp Ruby for C# Developers Cory Foy May 6th, 2006 http://www.cornetdesign.com
  • 34. Ruby Basics – Unit Tests • Let’s build a toaster! • Should be able to have toasting levels set • Should heat the bread based on the toasting levels • Different breads have different cooking times.St. Louis Code Camp Ruby for C# Developers Cory Foy May 6th, 2006 http://www.cornetdesign.com
  • 35. Ruby Basics – Unit Tests • Let’s start with a basic test class TestToaster < Test::Unit::TestCase def test_toast_bread toaster = Toaster.new bread = WonderBread.new toaster.heat_level = 5 toaster.toast(bread) assert_equal(“Nicely toasted”, bread.status) end endSt. Louis Code Camp Ruby for C# Developers Cory Foy May 6th, 2006 http://www.cornetdesign.com
  • 36. Ruby Basics – Unit Tests • And run it root@dilbert $ruby testtoaster.rb Loaded suite testtoaster Started E Finished in 0.0 seconds. 1) Error: test_toast_bread(TestToaster): NameError: uninitialized constant TestToaster::Toaster testtoaster.rb:4:in `test_toast_bread 1 tests, 0 assertions, 0 failures, 1 errorsSt. Louis Code Camp Ruby for C# Developers Cory Foy May 6th, 2006 http://www.cornetdesign.com
  • 37. Ruby Basics – Unit Tests • Next, let’s build our objects to allow our test to run class Toaster class WonderBread attr_accessor :heat_level attr_accessor :status end def toast(bread) end endSt. Louis Code Camp Ruby for C# Developers Cory Foy May 6th, 2006 http://www.cornetdesign.com
  • 38. Ruby Basics – Unit Tests • And run them root@dilbert $ruby testtoaster.rb Loaded suite testtoaster Started F Finished in 0.093 seconds. 1) Failure: test_toast_bread(TestToaster) [testtoaster.rb:10]: <"Nicely toasted"> expected but was <nil>. 1 tests, 1 assertions, 1 failures, 0 errorsSt. Louis Code Camp Ruby for C# Developers Cory Foy May 6th, 2006 http://www.cornetdesign.com
  • 39. Ruby Basics – Unit Tests • Finally, let’s make the test pass class Toaster def toast(bread) bread.status = “Nicely toasted” end end root@dilbert $ruby testtoaster.rb Loaded suite testtoaster Started . Finished in 0.0 seconds. 1 tests, 1 assertions, 0 failures, 0 errorsSt. Louis Code Camp Ruby for C# Developers Cory Foy May 6th, 2006 http://www.cornetdesign.com
  • 40. Ruby Basics – Unit Tests • We then keep writing tests to drive the behavior of the code we want to write • A side benefit is we get a suite of regression tests for our codeSt. Louis Code Camp Ruby for C# Developers Cory Foy May 6th, 2006 http://www.cornetdesign.com
  • 41. Ruby Basics – Unit Tests • How did the compiler help us again? – Find misspellings (Unit Tests) – Find improper usage (Unit Tests) – Enforce contracts (Duck Typing) – Find missing semicolons (No semicolons! ;))St. Louis Code Camp Ruby for C# Developers Cory Foy May 6th, 2006 http://www.cornetdesign.com
  • 42. Advanced Ruby - Modules • Blocks and Iterators • Modules • Mixins / Inheritance • Reflection • Other GoodiesSt. Louis Code Camp Ruby for C# Developers Cory Foy May 6th, 2006 http://www.cornetdesign.com
  • 43. Advanced Ruby - Blocks • A block is just a section of code between a set of delimters – { } or do..end { puts “Ho” } 3.times do puts “Ho “ end #prints “Ho Ho Ho”St. Louis Code Camp Ruby for C# Developers Cory Foy May 6th, 2006 http://www.cornetdesign.com
  • 44. Advanced Ruby - Blocks • Blocks can be associated with method invocations. The methods call the block using yield def format_print puts “Confidential. Do Not Disseminate.” yield puts “© SomeCorp, 2006” end format_print { puts “My name is Earl!” } -> Confidential. Do Not Disseminate. -> My name is Earl! -> © SomeCorp, 2006St. Louis Code Camp Ruby for C# Developers Cory Foy May 6th, 2006 http://www.cornetdesign.com
  • 45. Advanced Ruby - Blocks • Methods can act like the using statement from .NET using blocks def MyConnection.open(*args) conn = Connection.open(*args) if block_given? yield conn #passes conn to the block conn.close #closes conn when block finishes end return conn endSt. Louis Code Camp Ruby for C# Developers Cory Foy May 6th, 2006 http://www.cornetdesign.com
  • 46. Advanced Ruby - Iterators • Iterators in Ruby are simply methods that can invoke a block of code • Iterators typically pass one or more values to the block to be evaluatedSt. Louis Code Camp Ruby for C# Developers Cory Foy May 6th, 2006 http://www.cornetdesign.com
  • 47. Advanced Ruby - Iterators def fib_up_to(max) i1, i2 = 1, 1 while i1 <= max yield i1 i1, i2 = i2, i1+i2 # parallel assignment end end fib_up_to(100) {|f| print f + “ “} -> 1 1 2 3 5 8 13 21 34 55 89 • Pickaxe Book, page 50St. Louis Code Camp Ruby for C# Developers Cory Foy May 6th, 2006 http://www.cornetdesign.com
  • 48. Advanced Ruby - Modules • At their core, Modules are like namespaces in .NET or Java. module Kite def Kite.fly end end module Plane def Plane.fly end endSt. Louis Code Camp Ruby for C# Developers Cory Foy May 6th, 2006 http://www.cornetdesign.com
  • 49. Advanced Ruby - Mixins • Modules can’t have instances – they aren’t classes • But Modules can be included in classes, who inherit all of the instance method definitions from the module • This is called a mixin and is how Ruby does “Multiple Inheritance”St. Louis Code Camp Ruby for C# Developers Cory Foy May 6th, 2006 http://www.cornetdesign.com
  • 50. Advanced Ruby - Mixins module Print def print puts “Company Confidential” yield end end class Document include Print #... end doc = Document.new doc.print { “Fourth Quarter looks great!” } -> Company Confidential -> Fourth Quarter looks great!St. Louis Code Camp Ruby for C# Developers Cory Foy May 6th, 2006 http://www.cornetdesign.com
  • 51. Advanced Ruby - Reflection • How could we call the Length of a String at runtime in .NET? String myString = "test"; int len = (int)myString .GetType() .InvokeMember("Length", System.Reflection.BindingFlags.GetProperty, null, myString, null); Console.WriteLine("Length: " + len.ToString());St. Louis Code Camp Ruby for C# Developers Cory Foy May 6th, 2006 http://www.cornetdesign.com
  • 52. Advanced Ruby - Reflection • In Ruby, we can just send the command to the object myString = “Test” puts myString.send(:length) # 4St. Louis Code Camp Ruby for C# Developers Cory Foy May 6th, 2006 http://www.cornetdesign.com
  • 53. Advanced Ruby - Reflection • We can also do all kinds of fancy stuff #print out all of the objects in our system ObjectSpace.each_object(Class) {|c| puts c} #Get all the methods on an object “Some String”.methods #see if an object responds to a certain method obj.respond_to?(:length) #see if an object is a type obj.kind_of?(Numeric) obj.instance_of?(FixNum)St. Louis Code Camp Ruby for C# Developers Cory Foy May 6th, 2006 http://www.cornetdesign.com
  • 54. Ruby Basics – Other Goodies • RubyGems – Package Management for Ruby Libraries • Rake – A Pure Ruby build tool (can use XML as well for the build files) • RDoc – Automatically extracts documentation from your code and commentsSt. Louis Code Camp Ruby for C# Developers Cory Foy May 6th, 2006 http://www.cornetdesign.com
  • 55. Ruby and .NET • Why? – Provide Scripting ability in your apps – Quickly prototype – Class Introspection • What about JScript.NET? – Ruby is cross platform – JScript might be better choiceSt. Louis Code Camp Ruby for C# Developers Cory Foy May 6th, 2006 http://www.cornetdesign.com
  • 56. Ruby and .NET • Three projects in the works • Ruby to .NET Bridge – http://rubydotnet.sourceforge.net/ • MS Funded Ruby CLR project – http://www.plas.fit.qut.edu.au/rubynet/ • RubyCLR – http://rubyforge.org/projects/rubyclrSt. Louis Code Camp Ruby for C# Developers Cory Foy May 6th, 2006 http://www.cornetdesign.com
  • 57. Ruby and .NET • Bridge Example – Basic Arrays – Interacting with Objects – Creating Forms – Attaching to EventsSt. Louis Code Camp Ruby for C# Developers Cory Foy May 6th, 2006 http://www.cornetdesign.com
  • 58. Ruby Resources • Programming Ruby by Dave Thomas (the Pickaxe Book) • http://www.ruby-lang.org • http://www.rubyforge.org • http://www.rubycentral.org • http://www.ruby-doc.org • http://www.rubygarden.org • http://www.stlruby.orgSt. Louis Code Camp Ruby for C# Developers Cory Foy May 6th, 2006 http://www.cornetdesign.com