Ruby.new

#=> Hello World

• 标准版:

• print "hello world!"

• 太长了:

• puts "hello world!"

• 再短一点:

• p "hello world!"

#=> Comment

• # say hello

• 		
  =begin
    this is a long comment
  =end
  	  
  	

#=> variables

• local: time or _time

• instance: @time

• class: @@time

• global $time

#=> data types

• Numeric

  String

  Symbol

  Boolean

  Array

  Hash

#=> variables tricks

• "hello #{name}"

• a,b = b,a

• 3.times{ puts "hello"}

• "hello" * 3

#=> condition if

• 质樸的if:

• 
  if(a>5)
    puts a
  end

• 一行版:

• if a > 5 then puts a end

• 语义不够顺畅:

• puts a if a > 5

#=> condition unless

• 与if语义相反的unless

• puts "miss it" if !name

  puts "miss it" unless name

• 三元不能少:

• a > 5 ? puts(a) : "oh no"

#=> condition if else

• if elsif else:

• 
  if name == "jack"
    "i am rose"
  elsif name == "rose"
    "jack i miss u"
  else
    "get out from here"
  end
    

• 这个肯定是switch的场景啊:

• 
  case name
  when "jack" then "i am rose"
  when "rose" then "jack i miss u"
  else "get out from here"
  end
    

#=> loop

• 循环怎么写:

• 3.times{ puts "hello world" }

• for呢:

• 
  for x in [1,2,3]
    puts x
  end
  		

#=> loop

• while:

• 
  while i > 5 do
    i -= 1
  end
  i -= 1 while i > 5
  		

• while的好兄弟until:

• 
  until i <= 5 do
    i -= 1
  end
  i -= 1 until i<= 5
  		

#=> loop

• while true太不洋气了:

• 
  loop do
    puts "我自豪"
  end
  		

• 打断罪恶的连锁:

• break

  next

  redo

  retry

#=> method

• 质樸版:

• 
  def plus(x,y)
    z = x + y
    return z
  end
  plus(3, 4)
      

• 一步到位的:

• 
  def plus x,y
    x+y
  end
  plus 3,4
      

• 只有overriding没有overloading

#=> block

• 制造一个带有block的method:

• 
  def hello
    yield
  end
  
  hello {puts "hello, block"}
      

• 显式的告诉你这是怎么一回事(并不完全相同:

• 
  def hello &block
    block.call
  end
  
  hello {puts "hello, block"}
      

#=> lambda and block

• lambda 和 Proc:

• lambda{}

  Proc.new{}

• lambda和Proc的一点点区别:

• Proc中return会跳出当前作用域

  lambda中return不会跳出当前作用域

#=> block example

• 一些常用的block的例子:

• [1,2,3,4,5].each{|i| puts i}

  [1,2,3,4,5].each_with_index{|i, index| puts i, index}

  [1,2,3,4,5].map{|i| i**2 }

  [1,2,3,4,5].select{|i| i%2==0 }

  [1,2,3,4,5].reject{|i| i%2==0 }

  [1,2,3,4,5].inject{|sum, i| sum += i}

#=> class

• 正常的class实现:

• 
  class Bird
    attr_accessor :name, :sex
    def initialize name
      @name = name
    end
    
    def self.fly
      puts "bird can fly"
    end
    
    def say
      puts "i am #{@name}"
    end
  end
  
  bird = Bird.new("didi")
  bird.sex = "male"
  Bird.fly
      

#=> class more

• 继承怎么实现:

• 
  class LittleBird < Bird
    def initialize name
      super(name)
    end
  end
      

• 特殊属性访问控制:

• 
  attr_reader :name
  attr_writer :sex
      

#=> module

• interface怎么写:

• 
  ruby没有interface,只有比interface更强大的module与mixin机制
      

#=> module

• "有逻辑实现的interface":

• 
  module Eat
    def eat
      p "i can eat"
    end
  end
  
  module Sleep
    def sleep
      p "i can sleep"
    end
  end
  
  class Pig
    include Eat
    include Sleep
  end
  
  Pig.new.eat
  Pig.new.sleep
      

#=> module constants

• module constants访问:

• 
  module Math
    PI = 3.14
  end
  
  Math::PI
      

#=> module more

• module namespace:

• 
  module Foo
    module Bar
      def self.say
        p "Hi"
      end
    end
  end
  
  Foo::Bar.say
      

#=> module more

• another module namespace:

• 
  module Foo
    class Bar
      def say
        p "Hi"
      end
    end
  end
  
  Foo::Bar.new.say
      

#=> module singleton

• module的特殊用法singleton:

• 
  module Item
    extend self
    
    def name
      p "i'm item"
    end
  end
  
  Item.name
      

#=> ruby more

• monkey patch:

• 
  class Fixnum
    def plus n
      self + n
    end
  end
  
  1.plus 3
      

• and more...

#=> more

• 更多:

• [Fiber](https://gist.github.com/1050566)

  [Class](https://gist.github.com/872171)

  [System](https://gist.github.com/822091)

  [Proc](https://gist.github.com/874438)

puts "Thx"