gistfile1.ru

# Base class for an Item 
class LibraryItem
  # Type is a depricated method, undefining it will be safe
  undef_method :type 
  
  # Dynamically generates Getters/Setters for class
  # get_set :name, ConstClass
  def self.get_set(name, klass)
    define_method(name) {
      instance_variable_get("@#{name}").value
    }
    define_method("#{name}=") { |args|
      instance_variable_set("@#{name}", klass.new(args))
    }
    define_method("visit_#{name}") {
      instance_variable_get("@#{name}")
    }
  end
  

  def self.new_item(string)
    vals =[]
    string.each(',') { |val| vals << val.chomp(',') }
    vals.reverse!
    
    return Book.new(vals) if string =~ /^Book/
    return DVD.new(vals) if string =~ /^DVD/
    return CD.new(vals) if string =~/^CD/
    return Periodical.new(vals) if string =~ /^Periodical/
  end
  
  def initialize(vars)
    
    if vars.instance_of?(Array)
      new_from_array(vars)
    end
    if vars.instance_of?(Hash)
      vars.each do |key,value|
        self.send("#{key}=",value)
      end
    end
  end
  
  def accept(visitor)
    visitor.pre_visit(self)
    visitor.send("visit_#{self.class.to_s.downcase}", self)
    visitor.post_visit(self)
  end
  
  # Returns a list of all keys for each class
  def all_keys
    self.instance_variables.select {|var| var.delete!("@")}
  end
  
  def new_from_array(ary)
    dict = {}
    self.type = ary.pop
    self.schemaVersionNumber = ary.pop
    self.uniqueId = ary.pop
    self.title = ary.pop
  end
  
  get_set :type,Type
  get_set :schemaVersionNumber, SchemaVersionNumber
  get_set :uniqueId, UniqueId
  get_set :title, Title
end

# Specific subclass Book has attrs Author and Publisher
class Book < LibraryItem
  get_set :author, Author
  get_set :publisher, Publisher
  
  def new_from_array(ary)
    dict = super
    self.author = ary.pop
    self.publisher = ary.pop
  end
end

# Specific subclass CD has attrs Artist, Genre, Year
class CD < LibraryItem
  get_set :artist, Artist
  get_set :genre, Genre
  get_set :year, Year
  
  def new_from_array(ary)
    dict = super
    self.artist = ary.pop
    self.genre = ary.pop
    self.year = ary.pop
  end
end

# Specific subclass DVD has attrs Genre, Year 
class DVD < LibraryItem
  get_set :genre, Genre
  get_set :year, Year
  
  def new_from_array(ary)
    dict = super
    self.genre = ary.pop
    self.year = ary.pop
  end
end

# Specific class Periodical has attrs Volume, Issue
class Periodical < LibraryItem
  get_set :volume, Volume
  get_set :issue, Issue
  
  def new_from_array(ary)
    dict = super
    self.volume = ary.pop
    self.issue = ary.pop
  end
end