Design Pattern: Ruby Companion

4 Iterator ¥Ñ¥¿¡¼¥ó

4.2 Iterator¥Ñ¥¿¡¼¥ó¤Î¼ÂÁõ

4.2.1 ¥µ¥ó¥×¥ë¤½¤Î1: ÉáÄÌ¤Î¼ÂÁõ

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# Iterator Pattern
# sample1

class Book
  def initialize(name)
    @name = name
  end

  attr_reader :name
end

class BookShelf
  def initialize()
    @books = Array.new()
  end
  def [](index)
    return @books[index]
  end
  def append_book(book)
    @books << book
  end
  def length
    return @books.length
  end
  def iterator
    return BookShelfIterator.new(self)
  end
end

class BookShelfIterator
  def initialize(bookshelf)
    @bookShelf = bookshelf
    @index = 0
  end

  def has_next?()
    @index < @bookShelf.length
  end

  def next()
    book = @bookShelf[@index]
    @index += 1
    return book
  end
end

### main

if __FILE__ == $0
  bookShelf = BookShelf.new()
  bookShelf.append_book(Book.new("Around the World in 80 Days"))
  bookShelf.append_book(Book.new("Bible"))
  bookShelf.append_book(Book.new("Cinderella"))
  bookShelf.append_book(Book.new("Daddy-Long-Legs"))

  it = bookShelf.iterator()

  while it.has_next?
    book = it.next()
    print book.name, "\n"
  end
end

4.2.2 ¥µ¥ó¥×¥ë¤½¤Î2: ÆâÉô¥¤¥Æ¥ì¡¼¥¿

# Iterator Pattern
# sample2: using Enumerable

class Book
  def initialize(name)
    @name = name
  end

  attr_reader :name
end

class BookShelf
  include Enumerable

  def initialize()
    @books = Array.new()
  end

  def [](index)
    @books[index]
  end

  def <<(book)
    @books << book
  end

  def length()
    @books.length
  end

  def each()
    @books.each{|book|
      yield(book)
    }
  end
end

## main

if __FILE__ == $0
  bookShelf = BookShelf.new()
  bookShelf << Book.new("Around the World in 80 Days")
  bookShelf << Book.new("Bible")
  bookShelf << Book.new("Cinderella")
  bookShelf << Book.new("Daddy-Long-Legs")

  bookShelf.each{|book|
    print book.name, "\n"
  }

  bookstr =  bookShelf.collect{|book|
    '"'+book.name+'"'
  }.join(":")
  print bookstr, "\n"
end

4.2.3 ¥µ¥ó¥×¥ë¤½¤Î3: Struct¤ÈArray¤Î·Ñ¾µ

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# Iterator Pattern
# sample3: using Struct and inheretance of Array class

## Book class
Book = Struct.new("Book", :name)

## BookShelf class
class BookShelf < Array; end

## main
if __FILE__ == $0
  bookShelf = BookShelf.new()
  bookShelf << Book.new("Around the World in 80 Days")
  bookShelf << Book.new("Bible")
  bookShelf << Book.new("Cinderella")
  bookShelf << Book.new("Daddy-Long-Legs")

  bookShelf.each{|book|
    print book.name, "\n"
  }

  bookstr =  bookShelf.collect{|book|
    '"'+book.name+'"'
  }.join(":")
  print bookstr, "\n"
end

4.2.4 ¥µ¥ó¥×¥ë¤½¤Î4: Array¤Ø¤Î°Ñ¾ù(delegate)

# Iterator Pattern
# sample4: using delegate 

require 'delegate'

## Book class
Book = Struct.new("Book", :name)

## BookShelf class
class BookShelf < DelegateClass(Array)
  def initialize()
    super([])
  end
end


## main
if __FILE__ == $0
  bookShelf = BookShelf.new()
  bookShelf << Book.new("Around the World in 80 Days")
  bookShelf << Book.new("Bible")
  bookShelf << Book.new("Cinderella")
  bookShelf << Book.new("Daddy-Long-Legs")

  bookShelf.each{|book|
    print book.name, "\n"
  }

  bookstr =  bookShelf.collect{|book|
    '"'+book.name+'"'
  }.join(":")
  print bookstr, "\n"
end

4.2.5 ¥µ¥ó¥×¥ë¤½¤Î5: Array¤Ø¤Î°Ñ¾ù¤½¤Î2¡¦(forwarding)

# Iterator Pattern
# sample5: using forwarding

require 'forwardable'

## Book class
Book = Struct.new("Book", :name)

## BookShelf class
class BookShelf
  extend Forwardable
  def_delegators("@books", "<<", "[]", "length", "each")

  include Enumerable

  def initialize()
    @books = Array.new()
  end
end


## main
if __FILE__ == $0
  bookShelf = BookShelf.new()
  bookShelf << Book.new("Around the World in 80 Days")
  bookShelf << Book.new("Bible")
  bookShelf << Book.new("Cinderella")
  bookShelf << Book.new("Daddy-Long-Legs")

  bookShelf.each{|book|
    print book.name, "\n"
  }

  bookstr =  bookShelf.collect{|book|
    '"'+book.name+'"'
  }.join(":")
  print bookstr, "\n"
end

Ê¸ÀÕ: ¤¿¤«¤Ï¤·([email protected])

4 Iterator ¥Ñ¥¿¡¼¥ó

4.1 Iterator¥Ñ¥¿¡¼¥ó¤Î°Õ¿Þ

4.2 Iterator¥Ñ¥¿¡¼¥ó¤Î¼ÂÁõ

4.2.1 ¥µ¥ó¥×¥ë¤½¤Î1: ÉáÄÌ¤Î¼ÂÁõ

4.2.2 ¥µ¥ó¥×¥ë¤½¤Î2: ÆâÉô¥¤¥Æ¥ì¡¼¥¿

4.2.3 ¥µ¥ó¥×¥ë¤½¤Î3: Struct¤ÈArray¤Î·Ñ¾µ

4.2.4 ¥µ¥ó¥×¥ë¤½¤Î4: Array¤Ø¤Î°Ñ¾ù(delegate)

4.2.5 ¥µ¥ó¥×¥ë¤½¤Î5: Array¤Ø¤Î°Ñ¾ù¤½¤Î2¡¦(forwarding)

4.3 ¤ª¤Þ¤±

4.4 ¥½¡¼¥¹

4.4.1 ¥½¡¼¥¹¤Î¥é¥¤¥»¥ó¥¹