LEVEL 6: BLOCKS

gistfile1.rb

# YIELD - ARGUMENTS
def call_this_block
  yield "tweet"
end

call_this_block { |myarg| puts myarg.upcase }  # => TWEET


Timeline
  def each
    @user.friends.each do |friend| 
       friend.tweets.each { |tweet| yield tweet }
    end 
  end
end

timeline = Timeline.new(user)
timeline.each { |tweet| puts tweet }
timeline.each { |tweet| tweet.cache }


class Timeline
  def each
    @user.friends.each do |friend| 
       friend.tweets.each { |tweet| yield tweet }
    end 
  end
  include Enumerable
end
timeline.sort_by  { |tweet| tweet.created_at }
timeline.map      { |tweet| tweet.status }
timeline.find_all { |tweet| tweet.status =~ /\@codeschool/ }


# Final Example
class Game
  attr_accessor :name, :year, :system
  attr_reader :created_at

  def initialize(name, options={})
    self.name = name
    self.year = options[:year]
    self.system = options[:system]
    @created_at = Time.now
  end

  def play
    emulate do |emulator|
      emulator.play(self)
    end
  end

  def screenshot
    emulate do |emulator|
      emulator.start(self)
      emulator.screenshot
    end
  end

  private
  def emulate
    begin
      emulator = Emulator.new(system)
      yield emulator
    rescue Exception => e
      puts "Emulator failed: #{e}"
    end
  end
end