Le mani su Ruby

Il primo appuntamento del Torino Coding Society. Si parte con una introduzione a Ruby, al linguaggio e alla sua filosofia

Transcript

1. L E M A N I S U RUBY @arkham 30 /09/2013
2. RUBY W H A T I S
3. RUBY W H A T I S A programming language, written by a Japanese guy in 1995.
4. THIS GUY
5. YUKIHIRO MATSUMOTO a.k.a. MATZ
6. Why? “For me, the purpose of life is, at least partly, to have joy. Programmers often feel joy when they can concentrate on the creative side of programming, so Ruby is designed to make programmers happy.”
7. MINSWAN Matz Is Nice So We Are Nice
8. How? Ruby takes its origins from Perl, Smalltalk and Lisp. Matz tried to make the language natural, not simple. “Ruby is simple in appearance, but is very complex inside, just like our human body.”
9. CODE GTFO OR
10. Hello Ruby!
11. Hello World! def hello puts "Hello World!" end
12. Hello World! def hello puts "Hello World!" end hello() # Hello World!
13. Hello World! def hello puts "Hello World!" end hello() # Hello World! hello # Hello World!
14. Hello Matz! def hello(name) puts "Hello #{name}!" end
15. Hello Matz! def hello(name) puts "Hello #{name}!" end hello("Matz") # Hello Matz!
16. Hello Matz! def hello(name) puts "Hello #{name}!" end hello("Matz") # Hello Matz! hello "Matz" # Hello Matz!
17. Hello Torino! def hello(name = "Torino") puts "Hello #{name}!" end
18. Hello Torino! def hello(name = "Torino") puts "Hello #{name}!" end hello # Hello Torino!
19. Hello Torino! def hello(name = "Torino") puts "Hello #{name}!" end hello # Hello Torino! hello "Matz" # Hello Matz!
20. Strings string = "ciao" puts string # ciao puts string.reverse # oaic puts string.capitalize # Ciao puts string.upcase # CIAO
21. Strings string = "ciao" puts string # ciao puts string.reverse # oaic puts string.capitalize # Ciao puts string.upcase # CIAO
22. Strings string = "ciao" puts string # ciao puts string.reverse # oaic puts string.capitalize # Ciao puts string.upcase # CIAO
23. Strings string = "ciao" puts string # ciao puts string.reverse # oaic puts string.capitalize # Ciao puts string.upcase # CIAO
24. Strings string = "ciao" puts string # ciao puts string.reverse # oaic puts string.capitalize # Ciao puts string.upcase # CIAO
25. Arrays array = []
26. Arrays array.push "one" array << "two" array += ["three", "four"] p array # ["one", "two", "three", "four"] array = []
27. Hashes hash = {}
28. Hashes hash["one"] = 1 hash["two"] = 2 hash["three"] = 3 p hash # {"one"=>1, "two"=>2, "three"=>3} hash = {}
29. Ranges numbers = 1..10 p numbers.to_a # [1, 2, 3, 4, 5, 6, 7, 8, 9, 10] numbers = 1...10 p numbers.to_a # [1, 2, 3, 4, 5, 6, 7, 8, 9] characters = 'a'..'f' p characters.to_a # ["a", "b", "c", "d", "e", "f"]
30. Ranges numbers = 1..10 p numbers.to_a # [1, 2, 3, 4, 5, 6, 7, 8, 9, 10] numbers = 1...10 p numbers.to_a # [1, 2, 3, 4, 5, 6, 7, 8, 9] characters = 'a'..'f' p characters.to_a # ["a", "b", "c", "d", "e", "f"]
31. Ranges numbers = 1..10 p numbers.to_a # [1, 2, 3, 4, 5, 6, 7, 8, 9, 10] numbers = 1...10 p numbers.to_a # [1, 2, 3, 4, 5, 6, 7, 8, 9] characters = 'a'..'f' p characters.to_a # ["a", "b", "c", "d", "e", "f"]
32. Inline Conditions score = 100_000_000 if score > 9000 puts "score is over 9000!!" end # score is over 9000!!
33. Inline Conditions score = 100_000_000 if score > 9000 puts "score is over 9000!!" end # score is over 9000!! puts "score is over 9000!!" if score > 9000 # score is over 9000!!
34. LOOPS
35. Loops in Javascript var array = ["coffee", "ice", "sugar"];
36. Loops in Javascript for (var i=0; i<array.length; i++) { console.log("Adding " + array[i] + "..."); } // Adding coffee... // Adding ice... // Adding sugar... var array = ["coffee", "ice", "sugar"];
37. Loops in Ruby array = ["coffee", "ice", "sugar"]
38. Loops in Ruby array.each do |element| puts "Adding #{element}..." end # Adding coffee... # Adding ice... # Adding sugar... array = ["coffee", "ice", "sugar"]
39. Loops in Javascript var person = { first_name: "John", last_name: "Doe", age: 25 };
40. Loops in Javascript for (key in person) { console.log(key + " is " + person[key]); } // first_name is John // last_name is Doe // age is 25 var person = { first_name: "John", last_name: "Doe", age: 25 };
41. Loops in Ruby person = { first_name: "John", last_name: "Doe", age: 25 }
42. Loops in Ruby person.each do |key, value| puts "#{key} is #{value}" end # first_name is John # last_name is Doe # age is 25 person = { first_name: "John", last_name: "Doe", age: 25 }
43. CORE CONCEPTS
44. Everything OBJECT is an
45. Classes class Book end
46. Classes class Book end lotr = Book.new
47. Classes class Book end puts lotr.class # Book lotr = Book.new
48. Everything is an Object
49. Everything is an Object puts true.class # TrueClass
50. Everything is an Object puts true.class # TrueClass puts 5.class # Fixnum
51. Everything is an Object puts true.class # TrueClass puts 5.class # Fixnum puts nil.class # NilClass
52. TRUE OOP
53. Everything TRUE is unless it’s FALSE
54. Is this the real life, or is this just fantasy? puts "nil" if nil puts "false" if false puts "true" if true puts "0" if 0 puts "1" if 1
55. Is this the real life, or is this just fantasy? puts "nil" if nil puts "false" if false puts "true" if true puts "0" if 0 puts "1" if 1 # # # true # 0 # 1
56. Only nil and false FALSE ARE
57. CLASSES OPEN
58. Let’s say we want to add a yahoo method to every string in our application. Open Classes
59. Open Classes class String def yahoo "#{self} YAHOOOOO" end end
60. Open Classes class String def yahoo "#{self} YAHOOOOO" end end puts "Ruby".yahoo # Ruby YAHOOOOO
61. Open Classes class String def yahoo "#{self} YAHOOOOO" end end puts "Ruby".yahoo # Ruby YAHOOOOO puts "Ruby".yahoo.yahoo # Ruby YAHOOOOO YAHOOOOO
62. If Ruby lets you reopen any class, isn't that dangerous? WAIT!
63. If Ruby lets you reopen any class, isn't that dangerous? WAIT! Yeah.
64. Open Classes class Fixnum def +(other) 1 end end
65. Open Classes class Fixnum def +(other) 1 end end puts (1 + 1) == 1 # true
67. You can shoot yourself in your foot. Ruby gives you the freedom to do that. Ruby thinks you are clever enough to not shoot yourself in the foot. From Great Power..
68. AKA blocks Closures,
69. Closures in jQuery $(".post").each(function(){ $(this).css("color", "green"); });
70. Closures in Ruby, aka Blocks posts = ["first", "second", "third"] posts.each do |post| puts post.upcase end # FIRST # SECOND # THIRD
71. Closures in Ruby, aka Blocks posts = ["first", "second", "third"] posts.each do |post| puts post.capitalize * 2 end # FirstFirst # SecondSecond # ThirdThird
72. Closures in Ruby, aka Blocks numbers = 1..10 numbers.select do |num| num < 5 end # [1, 2, 3, 4]
73. Closures in Ruby, aka Blocks numbers = 1..10 numbers.reduce do |total, num| total + num end # 55
74. Closures in Ruby, aka Blocks numbers = 1..100 numbers.select do |num| num.odd? end.reduce do |total, num| total + num end # 2500
75. Closures in Ruby, aka Blocks numbers = 1..100 numbers.select do |num| num.even? end.reduce(1) do |total, num| total * num end # 3424322470251197624824643289520818597511 8675053719198827915654463488000000000000
76. Blocks are very flexible and dynamic. A lot of Ruby libraries use blocks for this reason. Ruby on Rails use them too! Blocks are good
77. Ju Liu @arkh4m weLaika @welaika PIZZA TIME! e End
78. tryruby.org Hands On
79. rubymonk.com Hands On
80. rubykoans.com Hands On
81. www.bloc.io/ruby-warrior Hands On