ruby-intro.key

Transcription

1 Ruby 程式語 言 入 門導覽 /6

2 Aga 什什麼是 Ruby 基本語法介紹 一些應 用

3 什什麼是 Ruby? 開放原碼 物件導向的動態直譯式 (interpreted) 程式語 言 簡單哲學 高 生產 力力 精巧 自然的語法 創造者 Yukihiro Matsumoto, a.k.a. Matz 靈感來來 自 Lisp, Perl, 和 Smalltalk

4 Taiwan 2012

5 Happy? 馬斯洛洛需求層次理理論 自我實現 尊重社交安全 生理理 DHH(Rails creator)

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8 Stackoverflow 和 Github 的熱 門排名

9 irb: Interactive Ruby irb(main):001:0> irb(main):001:0> => 2 irb(main):002:0>

10 PUTS 螢幕輸出 打開編輯器, 編輯 hello.rb puts "Hello World!" 執 行行 ruby hello.rb

11 Ruby 是動態強分型語 言 動態 Dynamic v.s. 靜態 Static typing Ruby/Perl/Python/PHP v.s. Java/C/C++ 強 Strong v.s. 弱 Weak typing Ruby/Perl/Python/Java v.s. PHP/C/C++

12 什什麼強? 弱? 分型 PHP code: Ruby code: $i = 1; echo "Value is " + $i # 1 C code: i=1 puts "Value is " + i #TypeError: can't convert Fixnum into String # from (irb):2:in `+' # from (irb):2 int a = 5; float b = a;

13 1. Ruby 基本語法

14 整數 Integer

15 浮點數 Float 後 面有

16 浮點數四則運算 puts puts 2.0 * 3.0 puts puts 9.0 / 2.0 # 3.0 # 6.0 # -3.0 # 4.5

17 整數四則運算 結果也會是整數 puts puts 2 * 3 puts 5-8 puts 9 / 2 # 3 # 6 # -1 # 4

18 更更多運算 puts 5 * (12-8) puts 98 + (59872 / (13*8)) * -52

19 字串串 String puts 'Hello, world!' puts '' puts 'Good-bye.'

20 字串串處理理 puts 'I like ' + 'apple pie.' puts 'You\'re smart!' puts '12' + 12 #<TypeError: can't convert Fixnum into String>

21 更更多字串串 方法 var1 = 'stop' var2 = 'foobar' var3 = "aabbcc" puts var1.reverse # 'pots' puts var2.length # 6 puts var3.upcase puts var3.downcase

22 字串串內插 verb = 'work' where = 'office' puts "I #{verb} at the #{where}"

23 Ruby 完全地物件導向 每樣東 西都是物件, 包括字串串和數字 # 輸出 "UPPER" puts "upper".upcase # 輸出 -5 的絕對值 puts -5.abs # 輸出 Fixnum puts 99.class # 輸出 "Ruby Rocks!" 五次 5.times do puts "Ruby Rocks!"

24 方法呼叫 Methods 所有東 西都是物件 (object), 可以呼叫物件的 方法, 例例如字串串 整數 浮點數 透過逗點. 來來對物件呼叫 方法

25 變數 Variable 小寫開頭, 偏好單字之間以底線 _ 分隔 composer = 'Mozart' puts composer + ' was "da bomb", in his day.' my_composer = 'Beethoven' puts 'But I prefer ' + my_composer + ', personally.'

26 型別轉換 Conversions var1 = 2 var2 = '5' puts var1.to_s + var2 # 25 puts var1 + var2.to_i # 7 puts 9.to_f / 2 # 4.5

27 常數 Constant 大寫開頭 foo = 1 foo = 2 Foo = 1 Foo = 2 # (irb):3: warning: already initialized constant Foo RUBY_PLATFORM ENV

28 nil 表 示未設定值 未定義 nil # nil nil.class # NilClass nil.nil? # true 42.nil? # false nil == nil # true false == nil # false

29 註解 # 偏好均使 用單 行行註解 # this is a comment line # this is a comment line =begin This is a comment line This is a comment line =

30 陣列列 Array a = [ 1, "cat", 3.14 ] puts a[0] # 輸出 1 puts a.size # 輸出 3 a[2] = nil puts a.inspect # 輸出字串 [1, "cat", nil]

31 更更多陣列列 方法 colors = ["red", "blue"] colors.push("black") colors << "white" puts colors.join(", ") # red, blue, black, white colors.pop puts colors.last #black

32 走訪迴圈 each method languages = ['Ruby', 'Javascript', 'Perl'] languages.each do lang puts 'I love ' + lang + '!' # I Love Ruby # I Love Javascript # I Love Perl

33 雜湊 Hash (Associative Array) config = { "foo" => 123, "bar" => 456 } puts config["foo"] # 輸出 123

34 字串串符號 Symbols 唯 一且不會變動的識別名稱 config = { :foo => 123, :bar => 456 } puts config[:foo] # 輸出 123

35 更更簡潔的語法 config = { foo: 123, bar: 456 } puts config[:foo] # 輸出 123

36 走訪雜湊 each method config = { :foo => 123, :bar => 456 } config.each do key, value puts "#{key} is #{value}" # foo is 123 # bar is 456

37 流程控制 Flow Control

38 比較 方法 puts 1 > 2 puts 1 < 2 puts 5 >= 5 puts 5 <= 4 puts 1 == 1 puts 2!= 1 puts ( 2 > 1 ) && ( 2 > 3 ) # and puts ( 2 > 1 ) ( 2 > 3 ) # or

39 控制結構 If Perl Style if account.total > puts "large account" elsif account.total > puts "medium account" else puts "small account"

40 三元運算 子 expression? true_expresion : false_expression x = 3 puts ( x > 3 )? " 大於三 " : " 小於或等於三 " # 輸出小於或等於三

41 控制結構 Case case name when "John" puts "Howdy John!" when "Ryan" puts "Whatz up Ryan!" else puts "Hi #{name}!"

42 迴圈 while, loop, until, next and break i=0 while ( i < 10 ) i += 1 next if i % 2 == 0 # 跳過雙數 puts i i = 0 loop do i += 1 break if i > 10 # 中斷迴圈 i = 0 i += 1 until i > 10 puts i # 輸出 11

43 真或假 只有 false 和 nil 是假, 其他為真 puts "not execute" if nil puts "not execute" if false puts "execute" if true # 輸出 execute puts "execute" if # 輸出 execute ( 和 JavaScript 不同 ) puts "execute" if 0 # 輸出 execute ( 和 C 不同 ) puts "execute" if 1 # 輸出 execute puts "execute" if "foo" # 輸出 execute puts "execute" if Array.new # 輸出 execute

44 Regular Expressions 與 Perl 接近的語法 # 抓出 手機號碼 phone = " " if phone =~ /(\d{3})-(\d{3})-(\d{4})/ ext = $1 city = $2 num = $3

45 方法定義 Methods def 開頭 結尾 retur n 可省略略, 最後 一 行行就是 def say_hello(name) result = "Hi, " + name return result puts say_hello('ihower') # 輸出 Hi, ihower 字串串相

46 預設參參數 def say_hello(name="nobody") result = "Hi, " + name result puts say_hello # 輸出 Hi, nobody 括號可以

47 ? 與! 的慣例例 方法名稱可以 用? 或! 結尾, 前者表 示會回傳 Boolean, 後者暗 示會有某種 side-effect array=[2,1,3] array.empty? # false array.sort # [1,2,3] array.inspect # [2,1,3] array.sort! # [1,2,3] array.inspect # [1,2,3]

48 物件導向 Object-Oriented Programming OOP 一種將 資料 和 方法 封裝到物件的設計 方式 使 用 類別 Class 來來定義出 物件 Object, 類別可說是物件的 Template 樣板

49 Car class

50 # 如何設計處理分數的相加, 假設分 是 x 分 是 y def add_rational_numerator(x1, y1, x2, y2) x1*y2 + x2*y1 資料跟 方法都沒有 def add_rational_denominator(x1, y1, x2, y2) y1*y2 # 2/3 + 3/4 x1 = 2 y1 = 3 x2 = 3 y2 = 4 answer_x = add_rational_numerator(x1, y1, x2, y2) answer_y = add_rational_denominator(x1, y1, x2, y2)

51 class MyRational attr_accessor :x, :y def = x, y def add(target) # 2/3 + 3/4 a = MyRational.new(2,3) b = MyRational.new(3,4) a.add(b)

52 類別 Classes 大寫開頭, 使 用 new 可以建立出物件 color_string = String.new color_string = "" # 等同 color_array = Array.new color_array = [] # 等同 color_hash = Hash.new color_hash = {} # 等同 time = Time.new puts time

53 大寫開頭的常 類別 Class class Person 建構式 物件變數 def = name def say(word) puts "#{word}, #{@name}" 字串串 p1 = Person.new("ihower") p2 = Person.new("ihover") p1.say("hello") # 輸出 Hello, ihower p2.say("hello") # 輸出 Hello, ihover

54 類別 Class ( 續 ) class Person = ihower def self.say 類別 方法 Person.say # 輸出 ihower

55 資料封裝 所有的物件變數 開頭 ) 類別變數 (@@ 開頭 ), 都是封裝在類別內部, 類別外無法存取 需透過定義 public 方法才可以存取到 class Person def = name p = Person.new('ihower') p.name => NoMethodError p.name='peny' => NoMethodError

56 class Person def = name def def = name p = Person.new('ihower') p.name => "ihower" p.name = "peny" => "peny"

57 方法封裝 預設是 public 公開 class MyClass def public_method private def private_method protected def protected_method class MyClass def public_method def private_method def protected_method public :public_method private :private_method protected :proected_method

58 類別 Class body 也可以執 行行程式 attr_accessor, attr_writer, attr_reader class Person class Person attr_accessor :name 等同於 def def = val

59 Class 繼承 class Pet attr_accessor :name, :age class Cat < Pet class Dog < Pet

60 Module (1) Namespace module MyUtil def self.foobar puts "foobar" MyUtil.foobar # 輸出 foobar

61 Module(2) Mixins 繼承 module Debug def who_am_i? "#{self.class.name} (\##{self.object_id}): #{self.to_s}" class Foo include Debug # 這個動作叫做 Mixin #... class Bar include Debug include XXX include YYY #... Ruby 使 用 Module 來來解決多重繼承問題 ph = Foo.new(" ") et = Bar.new(" ") ph.who_am_i? # 輸出 "Foo (#330450): " et.who_am_i? # 輸出 "Bar (#330420): "

62 多型 (Polymorphism) 即使不同類別, 只要介 面 一致就可以處理理 # 鴨子 class Duck def quack puts "quack!" # 野鴨 ( 不用繼承 ) class Mallard def quack puts "qwuaacck!! quak!"

63 動態型別 (duck typing) birds = [Duck.new, Mallard.new, Object.new] # 迭代陣列, 並呼叫方法 ( 無須擔心型別 ) birds.each do duck duck.quack if duck.respond_to? :quack

64 迭代器 iterator 不同於 while 迴圈 用法,each 是 一個陣列列的 方法, 走訪其中的元素, 我們稱作 迭代器 (iterator) 其中 do... 是 each 方法的參參數, 稱作匿名 方法 ( code block)

65 最簡單的迭代器 3.times do puts 'Good Job!' # Good Job! # Good Job! # Good Job!

66 code block 一種匿名 方法, 或稱作 closure { puts "Hello" } # 這是一個 block do puts "Blah" # 這也是一個 block puts "Blah"

67 code block 內部迭代器 (iterator) # 處理陣列 people people = ["David", "John", "Mary"] people.each do person puts person # 反覆五次 5.times { puts "Ruby rocks!" } # 從一數到九 1.upto(9) { x puts x } 所以我們將很少 用到

68 code block 其他迭代 方式 # 迭代並造出另一個陣列 a = [ "a", "b", "c", "d" ] b = a.map { x x + "!" } puts b.inspect # 結果是 ["a!", "b!", "c!", "d!"] # 找出符合條件的值 b = [1,2,3].find_all{ x x % 2 == 0 } b.inspect # 結果是 [2]

69 code block 當作判斷條件 # 迭代並根據條件刪除 a = [ "a", "b", "c" ] a.delete_if { x x >= "b" } # 結果是 ["a"] # 客製化排序 [2,1,3].sort! { a, b b <=> a } # 結果是 [3, 2, 1]

70 code block 有沒有 functional programming 的 fu? # 計算總和 (5..10).reduce { sum, n sum + n } # 找出最長字串 find the longest word longest = ["cat", "sheep", "bear"].reduce do memo, word ( memo.length > word.length )? memo : word

71 code block 僅執 行行 一次呼叫 pre- post- processing file = File.new("testfile", "r") #... 處理檔案 file.close # 但 Ruby 習慣 用以下寫法 File.open("testfile", "r") do file #... 處理檔案 # 檔案自動關閉

72 Yield 在 方法中使 用 yield 來來執 行行 code block # 定義方法 def call_block puts "Start" yield yield puts "End" call_block { puts "Blocks are cool!" } # 輸出 # "Start" # "Blocks are cool!" # "Blocks are cool!" # "End"

73 帶參參數的 code block def call_block yield(1) yield(2) yield(3) call_block { i puts "#{i}: Blocks are cool!" } # 輸出 # "1: Blocks are cool!" # "2: Blocks are cool!" # "3: Blocks are cool!"

74 Proc object 將 code block 明確轉成物件 def call_block(&block) block.call(1) block.call(2) block.call(3) call_block { i puts "#{i}: Blocks are cool!" } # 或是先宣告出 proc object proc_1 = Proc.new { i puts "#{i}: Blocks are cool!" } proc_2 = lambda { i puts "#{i}: Blocks are cool!" } call_block(&proc_1) call_block(&proc_2) # 輸出 # "1: Blocks are cool!" # "2: Blocks are cool!" # "3: Blocks are cool!"

75 傳遞不定參參數 def my_sum(*val) val.inject(0) { sum, v sum + v } puts my_sum(1,2,3,4) # 輸出 10

76 參參數尾 Hash 可省略略 { } def my_print(a, b, options) puts a puts b puts options[:x] puts options[:y] puts options[:z] my_print("a", "B", { :x => 123, :z => 456 } ) my_print("a", "B", :x => 123, :z => 456) # 結果相同 # 輸出 A # 輸出 B # 輸出 123 # 輸出 nil # 輸出 456

77 例例外處理理 raise, begin, rescue, ensure raise "Not works!!" # 丟出一個 RuntimeError # 自行自定例外物件 class MyException < RuntimeError raise MyException begin puts 10 / 0 rescue => e puts e.class ensure #... # 輸出 ZeroDivisionError

78 動 手練習 Exercises learnrubythehardway.org/book/

79 3. Ruby 的應 用 how ruby change the world!

80 Web framework MVC ORM URL Routing View Template

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83 Web Designer Tools Sass/Less/Haml Compass Middleman

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87 Testing/BDD Ruby community loves testing RSpec Cucumber

88 What s BDD? An improved xunit Framework Focus on clearly describe the expected behavior The emphasis is Tests as Documentation rather than merely using tests for verification.

89 Terminology changed New paradigm: Executable Specification Test becomes Spec Assertion becomes Expectation test method becomes example (RSpec) test case becomes example group (RSpec)

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92 DevOps Chef Puppet Vagrant

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96 Mac

97 Mac

98 Blogging (static HTML generator)

99 Redmine

100 RubyMotion

101 You can find more tools and libraries at:

102 動 手練習 Exercises 使 用 Jekyll 產 生靜態網 頁 並且部署到 GitHub Page 上

103 Thank you. 參參考資料 : Beginning Ruby 2nd. (Apress) Programming Ruby (The Pragmatic Programmers) The Well-Grounded Rubyist (Manning) Ruby 程式設計 (O Reilly) Foundation Rails 2 (frisof)