1.
Ruby 程式語⾔言
綜覽簡介
ihower@gmail.com
2013/4

2.
我是誰?
• 張⽂文鈿 a.k.a. ihower
• http://ihower.tw
• http://twitter.com/ihower
• Ruby Developer since 2006
• CTO, Faria Systems Ltd.
• The organizer of RubyConf Taiwan
• http://rubyconf.tw
• http://ruby.tw

3.
Agenda
• 什麼是 Ruby
• 基本語法
• Ruby 的幾個特點
• Ruby 的語⾔言實作
• 各式應⽤用
• ⽣生態圈

4.
什麼是 Ruby?
• 開放原碼、物件導向的動態直譯式
(interpreted)程式語⾔言
• 簡單哲學、⾼高⽣生產⼒力
• 精巧、⾃自然的語法
• 創造者 Yukihiro Matsumoto, a.k.a. Matz
• 靈感來⾃自 Lisp, Perl, 和 Smalltalk
• 設計的⺫⽬目的是要讓程式設計師 Happy

5.
Matz@RubyConf Taiwan 2012

6.
⾺馬斯洛需求層次理論
⽣生理
安全
社交
尊重
⾃自我實現
Happy?
DHH(Rails creator)

7.
http://redmonk.com/sogrady/2012/09/12/language-rankings-9-12/
Stackoverflow 和
Github 的熱⾨門排名

8.
irb: Interactive Ruby
⾺馬上動⼿手練習
irb(main):001:0>
irb(main):001:0> 1 + 1
=> 2
irb(main):002:0>

9.
PUTS 螢幕輸出
• 打開編輯器，編輯 hello.rb
• 執⾏行 ruby hello.rb
puts "Hello World!"

10.
Ruby 是動態強分型語⾔言
• 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++

11.
什麼強?弱?分型
i=1
puts "Value is " + i
#TypeError: can't convert Fixnum into
String
# from (irb):2:in `+'
# from (irb):2
$i = 1;
echo "Value is " + $i
# 1
PHP code: Ruby code:
int a = 5;
float b = a;
C code:

12.
1. Ruby 基本語法

13.
整數 Integer
5
-205
9999999999
0

14.
浮點數 Float
後⾯面有 .
54.321
0.001
-12.312
0.0

15.
浮點數四則運算
puts 1.0 + 2.0
puts 2.0 * 3.0
puts 5.0 - 8.0
puts 9.0 / 2.0
# 3.0
# 6.0
# -3.0
# 4.5

16.
整數四則運算
結果也會是整數
puts 1 + 2
puts 2 * 3
puts 5 - 8
puts 9 / 2
# 3
# 6
# -1
# 4

17.
更多運算
puts 5 * (12-8) + -15
puts 98 + (59872 / (13*8)) * -52

18.
字串 String
puts 'Hello, world!'
puts ''
puts 'Good-bye.'

19.
字串處理
puts 'I like ' + 'apple pie.'
puts 'You're smart!'
puts '12' + 12
#<TypeError: can't convert Fixnum into String>

20.
更多字串⽅方法
var1 = 'stop'
var2 = 'foobar'
var3 = "aAbBcC"
puts var1.reverse # 'pots'
puts var2.length # 6
puts var3.upcase
puts var3.downcase

21.
Ruby 完全地物件導向
每樣東⻄西都是物件，包括字串和數字。
# 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!"
end

22.
⽅方法呼叫 Methods
• 所有東⻄西都是物件(object)，可以呼叫物
件的⽅方法，例如字串、整數、浮點數。
• 透過逗點 . 來對物件呼叫⽅方法

23.
變數Variable
⼩小寫開頭，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.'

24.
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

25.
常數 Constant
⼤大寫開頭
foo = 1
foo = 2
Foo = 1
Foo = 2 # (irb):3: warning: already initialized constant Foo
RUBY_PLATFORM
ENV

26.
nil
表⽰示未設定值、未定義
nil # nil
nil.class # NilClass
nil.nil? # true
42.nil? # false
nil == nil # true
false == nil # false

27.
註解 #
偏好均使⽤用單⾏行註解
# this is a comment line
# this is a comment line
=begin
This is a comment line
This is a comment line
=end

28.
陣列 Array
a = [ 1, "cat", 3.14 ]
puts a[0] # 輸出 1
puts a.size # 輸出 3
a[3] = nil
puts a.inspect # 輸出字串 [1, "cat", nil]

29.
更多陣列⽅方法
colors = ["red", "blue"]
colors.push("black")
colors << "white"
puts colors.join(", ") # red, blue, black, white
colors.pop
puts colors.last #black

30.
雜湊 Hash
(Associative Array)
config = { "foo" => 123, "bar" => 456 }
puts config["foo"] # 輸出 123

31.
字串符號 Symbols
唯⼀一且不會變動的識別名稱
config = { :foo => 123, :bar => 456 }
puts config[:foo] # 輸出 123

32.
流程控制
Flow Control

33.
⽐比較⽅方法
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

34.
控制結構 If
if account.total > 100000
puts "large account"
elsif account.total > 25000
puts "medium account"
else
puts "small account"
end

35.
控制結構 If
if account.total > 100000
puts "large account"
elsif account.total > 25000
puts "medium account"
else
puts "small account"
end
Perl Style

36.
三元運算⼦子
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

37.
控制結構 Case
case name
when "John"
puts "Howdy John!"
when "Ryan"
puts "Whatz up Ryan!"
else
puts "Hi #{name}!"
end

38.
迴圈
while, loop, until, next and break
i = 0
loop do
i += 1
break if i > 10 # 中斷迴圈
end
i=0
while ( i < 10 )
i += 1
next if i % 2 == 0 #跳過雙數
end
i = 0
i += 1 until i > 10
puts i
# 輸出 11

39.
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

40.
Regular Expressions
與 Perl 接近的語法
# 抓出⼿手機號碼
phone = "123-456-7890"
if phone =~ /(d{3})-(d{3})-(d{4})/
ext = $1
city = $2
num = $3
end

41.
⽅方法定義 Methods
def 開頭 end 結尾
def say_hello(name)
result = "Hi, " + name
return result
end
puts say_hello('ihower')
# 輸出 Hi, ihower

42.
⽅方法定義 Methods
def 開頭 end 結尾
def say_hello(name)
result = "Hi, " + name
return result
end
puts say_hello('ihower')
# 輸出 Hi, ihower
字串相加

43.
⽅方法定義 Methods
def 開頭 end 結尾
def say_hello(name)
result = "Hi, " + name
return result
end
puts say_hello('ihower')
# 輸出 Hi, ihower
字串相加
return 可省
略，最後⼀一⾏行
就是回傳值

44.
? 與 ! 的慣例
⽅方法名稱可以⽤用?或!結尾，前者表⽰示會回傳 Boolean，
後者暗⽰示會有某種 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]

45.
類別 Classes
⼤大寫開頭，使⽤用 new 可以建⽴立出物件
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

46.
類別 Class
class Person
def initialize(name)
@name = name
end
def say(word)
puts "#{word}, #{@name}"
end
end
p1 = Person.new("ihower")
p2 = Person.new("ihover")
p1.say("Hello") # 輸出 Hello, ihower
p2.say("Hello") # 輸出 Hello, ihover

47.
類別 Class
class Person
def initialize(name)
@name = name
end
def say(word)
puts "#{word}, #{@name}"
end
end
p1 = Person.new("ihower")
p2 = Person.new("ihover")
p1.say("Hello") # 輸出 Hello, ihower
p2.say("Hello") # 輸出 Hello, ihover
建構式

48.
類別 Class
class Person
def initialize(name)
@name = name
end
def say(word)
puts "#{word}, #{@name}"
end
end
p1 = Person.new("ihower")
p2 = Person.new("ihover")
p1.say("Hello") # 輸出 Hello, ihower
p2.say("Hello") # 輸出 Hello, ihover
建構式
物件變數

49.
類別 Class
class Person
def initialize(name)
@name = name
end
def say(word)
puts "#{word}, #{@name}"
end
end
p1 = Person.new("ihower")
p2 = Person.new("ihover")
p1.say("Hello") # 輸出 Hello, ihower
p2.say("Hello") # 輸出 Hello, ihover
建構式
物件變數
字串相加

50.
類別 Class
class Person
def initialize(name)
@name = name
end
def say(word)
puts "#{word}, #{@name}"
end
end
p1 = Person.new("ihower")
p2 = Person.new("ihover")
p1.say("Hello") # 輸出 Hello, ihower
p2.say("Hello") # 輸出 Hello, ihover
建構式
物件變數
字串相加
⼤大寫開頭的
常數

51.
類別 Class (續)
class Person
@@name = “ihower”
def self.say
puts @@name
end
end
Person.say # 輸出 Hello, ihower

52.
類別 Class (續)
class Person
@@name = “ihower”
def self.say
puts @@name
end
end
Person.say # 輸出 Hello, ihower
類別變數

53.
類別 Class (續)
class Person
@@name = “ihower”
def self.say
puts @@name
end
end
Person.say # 輸出 Hello, ihower
類別變數
類別⽅方法

54.
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 ⽅方法才可以存取到
class Person
def initialize(name)
@name = name
end
end
p = Person.new('ihower')
p.name
=> NoMethodError
p.name='peny'
=> NoMethodError

55.
class Person
def initialize(name)
@name = name
end
def name
@name
end
def name=(name)
@name = name
end
end
p = Person.new('ihower')
p.name
=> "ihower"
p.name="peny"
=> "peny"

56.
⽅方法封裝
預設是 public 公開
class MyClass
def public_method
end
def private_method
end
def protected_method
end
public :public_method
private :private_method
protected :proected_method
end
class MyClass
def public_method
end
private
def private_method
end
protected
def protected_method
end
end

57.
類別 Class body 也可以執⾏行程式
attr_accessor, attr_writer, attr_reader
class Person
attr_accessor :name
end
class Person
def name
@name
end
def name=(val)
@name = val
end
end
等同於

58.
Class 繼承
class Pet
attr_accessor :name, :age
end
class Cat < Pet
end
class Dog < Pet
end

59.
Module (1) Namespace
module MyUtil
def self.foobar
puts "foobar"
end
end
MyUtil.foobar
# 輸出 foobar

60.
Module(2) Mixins
module Debug
def who_am_i?
"#{self.class.name} (##{self.object_id}): #{self.to_s}"
end
end
class Foo
include Debug # 這個動作叫做 Mixin
# ...
end
class Bar
include Debug
# ...
end
ph = Foo.new("12312312")
et = Bar.new("78678678")
ph.who_am_i? # 輸出 "Foo (#330450): 12312312"
et.who_am_i? # 輸出 "Bar (#330420): 78678678"

61.
Module(2) Mixins
module Debug
def who_am_i?
"#{self.class.name} (##{self.object_id}): #{self.to_s}"
end
end
class Foo
include Debug # 這個動作叫做 Mixin
# ...
end
class Bar
include Debug
# ...
end
ph = Foo.new("12312312")
et = Bar.new("78678678")
ph.who_am_i? # 輸出 "Foo (#330450): 12312312"
et.who_am_i? # 輸出 "Bar (#330420): 78678678"
Ruby 使⽤用
Module 來解決
多重繼承問題

62.
⾛走訪迴圈
each method
languages = ['Ruby', 'Javascript', 'Perl']
languages.each do |lang|
puts 'I love ' + lang + '!'
end
# I Love Ruby
# I Love Javascript
# I Love Perl

63.
迭代器 iterator
• 不同於 while 迴圈⽤用法，each 是⼀一個陣
列的⽅方法，⾛走訪其中的元素，我們稱作
迭代器(iterator)
• 其中 do .... end 是 each ⽅方法的參數，稱
作匿名⽅方法( code block)

64.
最簡單的迭代器
3.times do
puts 'Good Job!'
end
# Good Job!
# Good Job!
# Good Job!

65.
code block
⼀一種匿名⽅方法，或稱作 closure
{ puts "Hello" } # 這是一個 block
do
puts "Blah" # 這也是一個 block
puts "Blah"
end

66.
code block
內部迭代器(iterator)
# 處理陣列 people
people = ["David", "John", "Mary"]
people.each do |person|
puts person
end
# 反覆五次
5.times { puts "Ruby rocks!" }
# 從一數到九
1.upto(9) { |x| puts x }

67.
code block
內部迭代器(iterator)
# 處理陣列 people
people = ["David", "John", "Mary"]
people.each do |person|
puts person
end
# 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
很少⽤用到
while, until, for 等迴圈

68.
code block
其他迭代⽅方式
# 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).inject {|sum, n| sum + n }
# 找出最長字串find the longest word
longest = ["cat", "sheep", "bear"].inject do |memo,
word|
( memo.length > word.length )? memo : word
end

71.
code block
僅執⾏行⼀一次呼叫
file = File.new("testfile", "r")
# ...處理檔案
file.close
File.open("testfile", "r") do |file|
# ...處理檔案
end
# 檔案自動關閉

72.
Yield
在⽅方法中使⽤用 yield 來執⾏行 code block
# 定義方法
def call_block
puts "Start"
yield
yield
puts "End"
end
call_block { puts "Blocks are cool!" }
# 輸出
# "Start"
# "Blocks are cool!"
# "Blocks are cool!"
# "End"

73.
帶參數的 code block
def call_block
yield(1)
yield(2)
yield(3)
end
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)
end
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.
傳遞不定參數
def my_sum(*val)
val.inject(0) { |sum, v| sum + v }
end
puts my_sum(1,2,3,4)
# 輸出 10

76.
參數尾 Hash 可省略 { }
def my_print(a, b, options)
puts a
puts b
puts options[:x]
puts options[:y]
puts options[:z]
end
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.
例外處理
raise, begin, rescue, ensure
begin
puts 10 / 0
rescue => e
puts e.class
ensure
# ...
end
# 輸出 ZeroDivisionError
raise "Not works!!"
# 丟出一個 RuntimeError
# 自行自定例外物件
class MyException < RuntimeError
end
raise MyException

78.
2. Ruby 的特點
Ruby supports multiple programming paradigms

79.
1. Object-Oriented
物件導向程式設計

80.
Everything in Ruby is
object, even class.

81.
Ruby Object Model
class A
end
class B < A
end
obj = B.new
obj.class # B
B.superclass # A
B.class # Class
obj B
Object
Class
A
class class
super
super

82.
class object is an object
of the class Class
obj B
Object
Class
A
class class
super
super
class
class
class
class A
end
class B < A
end
obj = B.new
obj.class # B
B.superclass # A
B.class # Class

83.
class A
end
module B
end
module C
end
class D < A
include B
include C
end
D.ancestors
=> [D, C, B, A, Object, Kernel, BasicObject]
module
obj D
A
Mixin
B,C
class
super
super

84.
class A
def foo
end
end
obj1 = A.new
obj2 = A.new
what’s metaclass?
obj2
Object
A
class
super
obj2
class

85.
obj2
Object
A
class
super
obj2’s
metaclass
obj2
class
super
class A
def foo
end
end
obj1 = A.new
obj2 = A.new
def obj2.bar
# only obj2 has bar method,
# called singleton method
end
# another way
class << obj1
def baz
#only obj1 has baz method
end
end
P.S. well, number and symbol have no metaclass
metaclassalso known as singleton, eigenclass, ghost class, virtual class.
every object has his own metaclass

86.
A
A’s
metaclass
super
Class
class
B
class
class A
# way1
def self.foo
end
# way2
class << self
def bar
end
end
end
# way3
def A.baz
end
A.foo
A.bar
A.baz
class object has its metaclass too.
so the singleton method is class
method!!

87.
動態型別 (duck typing)
會聒聒叫的就是鴨⼦子
# 鴨子
class Duck
def quack
puts "quack!"
end
end
# 野鴨 (不用繼承)
class Mallard
def quack
puts "qwuaacck!! quak!"
end
end

88.
Class 不是 Type
⼀一個物件可以做什麼才是重點
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
end

89.
Duck Typing(from wikipedia)
• duck typing is a style of dynamic typing in
which an object's methods and properties
determine the valid semantics, rather than
its inheritance from a particular class or
implementation of a specific interface

90.
prototype-based programming
Like JavaScript, Ruby can do, too
Animal = Object.new
def Animal.run
end
def Animal.sit
end
Cat = Animal.clone
Cat.run
Dog = Animal.clone
Dog.run

91.
class-oriented programming
v.s.
object-oriented programming
http://stackoverflow.com/questions/546670/what-is-the-difference-between-class-
oriented-and-object-oriented-programming

92.
“With Ruby, you can think in terms of
classes or in terms of objects.With
Javascript, you can think in terms of
prototypes or in terms of objects.With
Java and C++, classes are your only option.”
by Giles Bowkett

93.
2. Functional Programming
函數式程式設計
http://www.slideshare.net/ihower/fp-osdc2012v2
https://github.com/JuanitoFatas/Ruby-Functional-Programming

94.
(1) Higher-Order Functions
tickets = { "a" => 1100, "b" => 900, "c" => 800 }
highest_price = 0
tickets.each do |ticket, price|
if price < 1000
highest_price = price if price > highest_price
end
end
highest_price # 900

95.
Higher-Order Functions
(cont.)
tickets = { "a" => 1100, "b" => 900, "c" => 800 }
tickets.map{ |x| x[1] }.select{ |x| x < 1000 }.max # 900

96.
pre- and Post-processing
usage example
f = File.open("myfile.txt", 'w')
f.write("Lorem ipsum dolor sit amet")
f.write("Lorem ipsum dolor sit amet")
f.close
# using block
File.open("myfile.txt", 'w') do |f|
f.write("Lorem ipsum dolor sit amet")
f.write("Lorem ipsum dolor sit amet")
end

97.
Dynamic Callbacks
Sinatra usage example
get '/posts' do
#.. show something ..
end
post '/posts' do
#.. create something ..
end
put '/posts/:id' do
#.. update something ..
end
delete '/posts/:id' do
#.. annihilate something ..
end

98.
Dynamic Callbacks
server = Server.new
server.handle(/hello/) do
puts "Hello at #{Time.now}"
end
server.handle(/goodbye/) do
puts "goodbye at #{Time.now}"
end
server.execute("/hello")
# Hello at Wed Apr 21 17:33:31 +0800 2010
server.execute("/goodbye")
# goodbye at Wed Apr 21 17:33:42 +0800 2010

99.
class Server
def initialize
@handlers = {}
end
def handle(pattern, &block)
@handlers[pattern] = block
end
def execute(url)
@handlers.each do |pattern, block|
if match = url.match(pattern)
block.call
break
end
end
end
end

100.
(2) Everything is an
expression
if found_dog == our_dog
name = found_dog.name
message = "We found our dog #{name}!"
else
message = "No luck"
end

101.
Everything is an
expression (cont.)
message = if found_dog == my_dog
name = found_dog.name
"We found our dog #{name}!"
else
"No luck"
end

102.
(3) Lazy enumerators
require 'prime'
Prime.to_a # 這樣是無窮數列...
Prime.take(10).to_a
# [2, 3, 5, 7, 11, 13, 17, 19, 23, 29]
Prime.lazy.select{ |x| x % 4 == 3 }.take(10).to_a
# => [3, 7, 11, 19, 23, 31, 43, 47, 59, 67]

103.
3. Metaprogramming
⽤用程式寫程式
http://ihower.tw/blog/archives/4279

104.
Two types of meta-
programming
• Code Generation
• eg. Rails scaffold
• Reflection
• eg. Class Macro

105.
Class Bodies Aren’t
Special
class Demo
a = 1
puts a
def self.say
puts "blah"
end
say # you can execute class method in class body
end
# 1
# blah

106.
Introspection (反射機制)
# 這個物件有什麼方法
Object.methods
=> ["send", "name", "class_eval", "object_id", "new",
"singleton_methods", ...]
# 這個物件有這個方法嗎？
Object.respond_to? :name
=> true

107.
define_method
動態定義⽅方法
class Dragon
define_method(:foo) { puts "bar" }
['a','b','c','d','e','f'].each do |x|
define_method(x) { puts x }
end
end
dragon = Dragon.new
dragon.foo # 輸出 "bar"
dragon.a # 輸出 "a"
dragon.f # 輸出 "f"

108.
Rails example
class Firm < ActiveRecord::Base
has_many :clients
has_one :account
belongs_to :conglomorate
end
# has_many 是 AciveRecord 的 class method
# 其內容是動態定義出 Firm 的一堆 instance methods
firm = Firm.find(1)
firm.clients
firm.clients.size
firm.clients.build
firm.clients.destroy_all

109.
Memorize example
(Class Macro)
class Account
def calculate
@calculate ||= begin
sleep 10 # expensive calculation
5
end
end
end
a = Account.new
a.caculate # need waiting 10s to get 5
a.caculate # 5
a.caculate # 5
a.caculate # 5

110.
memoize method
class Account
def calculate
sleep 2 # expensive calculation
5
end
memoize :calculate
end
a = Account.new
a.calculate # need waiting 10s to get 5
a.calculate # 5

111.
class Class
def memoize(name)
original_method = "_original_#{name}"
alias_method :"#{original_method}", name
define_method name do
cache = instance_variable_get("@#{name}")
if cache
return cache
else
result = send(original_method) # Dynamic Dispatches
instance_variable_set("@#{name}", result)
return result
end
end
end
end

112.
It’s general for any class
class Car
def run
sleep 100 # expensive calculation
“done”
end
memoize :run
end
c = Car.new
c.run # need waiting 100s to get done
c.run # done

113.
Method Missing
car = Car.new
car.go_to_taipei
# go to taipei
car.go_to_shanghai
# go to shanghai
car.go_to_japan
# go to japan

114.
class Car
def go(place)
puts "go to #{place}"
end
def method_missing(name, *args)
if name.to_s =~ /^go_to_(.*)/
go($1)
else
super
end
end
end
car = Car.new
car.go_to_taipei
# go to taipei
car.blah # NoMethodError: undefined method `blah`

115.
XML builder example
builder = Builder::XmlMarkup.new(:target=>STDOUT, :indent=>2)
builder.person do |b|
b.name("Jim")
b.phone("555-1234")
b.address("Taipei, Taiwan")
end
# <person>
# <name>Jim</name>
# <phone>555-1234</phone>
# <address>Taipei, Taiwan</address>
# </person>

116.
DSL
(Domain-Specific Language)
• Internal DSL
• 沿⽤用程式語⾔言本⾝身的 Syntax
• Ruby 有⾮非常好的能⼒力可以作為 Internal
DSL 之⽤用
• External DSL
• ⾃自⾏行發明 Syntax，再⽤用程式語⾔言去解析

117.
4. Encodings
http://ihower.tw/blog/archives/2722

118.
UCS v.s. CSI
• UCS (Universal Character Set)
• 語⾔言內部統⼀一轉換成使⽤用 UTF-16 或
UTF-8，Java/Python/Perl 等⼤大部分語⾔言
都這樣做
• CSI (Character Set Independent)
• Ruby 內建⽀支援 99 種 Encodings，並不
做轉換

119.
pick one encoding, likely Unicode, and works all data in one format? No.
Ruby 1.9 make it possible to work
with data with 99 encoding.

120.
1.9.3-p392 :024 > Encoding.name_list
=> ["ASCII-8BIT", "UTF-8", "US-ASCII", "Big5", "Big5-HKSCS", "Big5-UAO", "CP949",
"Emacs-Mule", "EUC-JP", "EUC-KR", "EUC-TW", "GB18030", "GBK", "ISO-8859-1",
"ISO-8859-2", "ISO-8859-3", "ISO-8859-4", "ISO-8859-5", "ISO-8859-6", "ISO-8859-7",
"ISO-8859-8", "ISO-8859-9", "ISO-8859-10", "ISO-8859-11", "ISO-8859-13",
"ISO-8859-14", "ISO-8859-15", "ISO-8859-16", "KOI8-R", "KOI8-U", "Shift_JIS",
"UTF-16BE", "UTF-16LE", "UTF-32BE", "UTF-32LE", "Windows-1251", "BINARY", "IBM437",
"CP437", "IBM737", "CP737", "IBM775", "CP775", "CP850", "IBM850", "IBM852", "CP852",
"IBM855", "CP855", "IBM857", "CP857", "IBM860", "CP860", "IBM861", "CP861", "IBM862",
"CP862", "IBM863", "CP863", "IBM864", "CP864", "IBM865", "CP865", "IBM866", "CP866",
"IBM869", "CP869", "Windows-1258", "CP1258", "GB1988", "macCentEuro", "macCroatian",
"macCyrillic", "macGreek", "macIceland", "macRoman", "macRomania", "macThai",
"macTurkish", "macUkraine", "CP950", "Big5-HKSCS:2008", "CP951", "stateless-ISO-2022-
JP", "eucJP", "eucJP-ms", "euc-jp-ms", "CP51932", "eucKR", "eucTW", "GB2312", "EUC-
CN", "eucCN", "GB12345", "CP936", "ISO-2022-JP", "ISO2022-JP", "ISO-2022-JP-2",
"ISO2022-JP2", "CP50220", "CP50221", "ISO8859-1", "Windows-1252", "CP1252",
"ISO8859-2", "Windows-1250", "CP1250", "ISO8859-3", "ISO8859-4", "ISO8859-5",
"ISO8859-6", "Windows-1256", "CP1256", "ISO8859-7", "Windows-1253", "CP1253",
"ISO8859-8", "Windows-1255", "CP1255", "ISO8859-9", "Windows-1254", "CP1254",
"ISO8859-10", "ISO8859-11", "TIS-620", "Windows-874", "CP874", "ISO8859-13",
"Windows-1257", "CP1257", "ISO8859-14", "ISO8859-15", "ISO8859-16", "CP878",
"Windows-31J", "CP932", "csWindows31J", "SJIS", "PCK", "MacJapanese", "MacJapan",
"ASCII", "ANSI_X3.4-1968", "646", "UTF-7", "CP65000", "CP65001", "UTF8-MAC", "UTF-8-
MAC", "UTF-8-HFS", "UTF-16", "UTF-32", "UCS-2BE", "UCS-4BE", "UCS-4LE", "CP1251",
"UTF8-DoCoMo", "SJIS-DoCoMo", "UTF8-KDDI", "SJIS-KDDI", "ISO-2022-JP-KDDI",
"stateless-ISO-2022-JP-KDDI", "UTF8-SoftBank", "SJIS-SoftBank", "locale", "external",
"filesystem", "internal"]

121.
All String are Encoded
• In Ruby 1.9 a String is a collection of
encoded characters.
除了 raw bytes，還包括 Encoding 資訊。
>> "中文".encoding.name
=> "UTF-8"
Encoding
object

122.
In Ruby 1.9, String has attached
Encoding object, and works in
characters.

123.
Transcoding
改變編碼
utf8 = "測試"
utf8.bytesize # 6
utf8.bytes.to_a # [230, 184, 172, 232, 169, 166]
big5 = utf8.encode("big5")
big5.encoding.name # ”Big5”
big5.bytesize # 4
big5.bytes.to_a # [180, 250, 184, 213]

124.
Transcoding fails
轉碼失敗
str = "Résumé"
str.encode("big5")
=> Encoding::UndefinedConversionError: "xC3xA9"
from UTF-8 to Big5
from (irb):2:in `encode'
from (irb):2
from /usr/local/bin/irb19:12:in `<main>'

125.
Force Transcoding
改變編碼，但不改 byte data
utf8 = "測試"
big5 = utf8.encode("big5")
big5.valid_encoding?
=> true
big5.force_encoding("utf-8")
big5.valid_encoding?
=> false

126.
Force Transcoding fails
編碼不對無法進⼀一步操作
big5.valid_encoding? # false
big5 =~ /123456/
=> ArgumentError: invalid byte sequence in UTF-8
from (irb):11
from /usr/local/bin/irb19:12:in `<main>'

127.
Encoding.compatible?
例如:ASCII with a bigger Encoding
ascii = "my ".force_encoding("ascii")
utf8 = "Résumé"
# 檢查相容性
Encoding.compatible?(ascii, utf8)
#<Encoding:UTF-8>
# 相加
my_resume = ascii + utf8
puts my_resume # "My Résumé"
puts my_resume.encoding.name # UTF-8

128.
Encoding.compatible?
不相容不能加在⼀一起
big5 = "測試".encode("big5")
utf8 = "Résumé"
# 檢查相容性
Encoding.compatible?(big5, utf8) # nil
# 相加
big5 + utf8
=> Encoding::CompatibilityError: incompatible character
encodings: Big5 and UTF-8
from (irb):25
from /usr/local/bin/irb19:12:in `<main>'

129.
3. Ruby 的實作

130.
程式語⾔言和程式語⾔言的實作，
是兩回事
(雖然很多語⾔言只有⼀一種實作)
程式語⾔言本⾝身沒有效能快慢，程式語⾔言的實作才有

131.
CRuby / MRI (Matz's Ruby Interpreter)
• 1.8.7 is dead
• 1.9.3
• 2.0 is released at 2/24/2013 (⼆二⼗十週年)

132.
JRuby

133.
Rubinius

134.
Concurrency models
的爭論
• process-based
• CRuby has GVL (globalVM lock)
• thread-based
• reactor pattern
• eventmachine (Ruby library)
• node.js (JavaScript)

135.
IronRuby

136.
MacRuby

137.
RubyMotion

138.
mruby

139.
4. Ruby 的應⽤用
how ruby change the world!

140.
Web framework
• MVC
• ORM
• URL Routing
• View Template

141.
Web Designer Tools
• Sass/Less/Haml
• Compass
• Middleman

142.
Testing/BDDRuby community loves testing
• RSpec
• Cucumber
http://ihower.tw/blog/archives/5438
http://ihower.tw/blog/archives/5983

143.
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.

144.
Terminology changed
New paradigm: Executable Specification
• “Test” becomes “Spec”
• “Assertion” becomes “Expectation”
• “test method” becomes “example” (RSpec)
• “test case” becomes “example group” (RSpec)

145.
class OrderTest < Test::Unit::TestCase
def setup
@order = Order.new
end
def test_order_status_when_initialized
assert_equal @order.status, "New"
end
def test_order_amount_when_initialized
assert_equal @order.amount, 0
end
end
Test::Unit 寫法

146.
describe Order do
before do
@order = Order.new
end
context "when initialized" do
it "should have default status is New" do
@order.status.should == "New"
end
it "should have default amount is 0" do
@order.amount.should == 0
end
end
end
RSpec 寫法

147.
DevOps
• Chef
• Puppet
• Vagrant

148.
Mac

149.
Mac

150.
Blogging
(static HTML generator)

151.
Redmine

152.
5. Ruby ⽣生態圈

153.
1. Editors & IDEs

154.
Vim for Rails

155.
Emacs for Rails

156.
2.Web Services &
Monitors

157.
3.Hosting

158.
3.a
PaaS (Platform as a Service)

159.
3.b
⾼高C/P值的VPS (Virtual Private Server)

160.
3.b
IaaS (Infrastructure as a service)
Cloud Hosing

161.
4. Consulting

162.
http://www.workingwithrails.com/

163.
5. Conferences

164.
6. Books

165.
http://www.pragprog.com/

166.
閱讀練習時，⼩小⼼心 Rails 版本差異
1.2, 2.0, 2.1, 2.2, 2.3, 3.0, 3,1, 3.2
4.0 書籍尚未上市

167.
http://guides.rubyonrails.org/

168.
7.Video

169.
http://peepcode.com/

170.
8.Website & Blog
(free)

171.
http://weblog.rubyonrails.org/

172.
http://www.rubyinside.com/

173.
http://ruby5.envylabs.com

174.
http://railscasts.com/

175.
http://www.rubyflow.com/

176.
http://github.com/

177.
9. Ruby Community
in Taiwan

178.
Ruby Tuesday 聚會

179.
ptt.cc #Ruby 版

180.
http://railsfun.tw/

181.
Thank you.
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 (friendsof)
http://rubyonrails.org/ecosystem
http://infoether.com/ruby-and-rails-whitepaper

182.
We’re hiring
• Ruby on Rails developer
• Front-end web developer
• http://faria.co