iterator pattern

iterator_pattern.rb

################# Enumerable Mixin
class Account
  attr_accessor :name, :balance
  
  def initialize(name, balance)
    @name = name
    @balance = balance
  end
  
  def <=>(other)
    balance <=> other.balance
  end
end

class Portfolio
  include Enumerable
  
  def initialize
    @accounts = []
  end
  
  def each(&block)
    @accounts.each(&block)
  end
  
  def add_account(account)
    @accounts << account
  end
end

my_portfolio.any? {|account| account.balance > 2000}
my_portfolio.all? {|account| account.balance >= 10}








################# Abusing the Iteratr Pattern (change resistant or not)
array = ['red', 'green', 'blue', 'purple']

array.each do |color|
  puts(color)
  if color == 'green'
    array.delete(color)
  end
end

#=> red, green, purple


class ChangeResistantArrayIterator
  # make a shallow copy of the array -- copy points to the original contents
  def initialize(array)
    @array = Array.new(array)
    @index = 0
  end
end






################# Amphibious IO object
f = File.open('name.txt')
while not f.eof?
  puts f.readline
end
f.close


f = File.open('name.txt')
f.each {|line| puts(line)}
f.close