small excercise to refresh some metaprogramming stuff

gistfile1.rb

# just a small refresher on some meta stuff - haven't commited all of it to
# muscle memory yet
class NoteBook

  attr_accessor :notes

  class << self
    attr_accessor :subclasses
  end

  @subclasses = []

  def self.inherited(subclass)
    NoteBook.subclasses << subclass
  end

  def self.note(desc, *args, &block)
    name = "note_" + desc.gsub(/\s+/, "_").downcase
    define_method(name, *args) do
      @notes += "# #{desc}\n\n"
      instance_eval(&block)
      @notes += "\n\n"
    end
  end

  def initialize
    @notes = ""
  end

  def content(text)
    @notes += "#{text}\n\n"
  end

  def footer(text)
    @notes += "#{text}"
  end

end

at_exit do
  all_notes = ""
  NoteBook.subclasses.each do |subclass|
    sub = subclass.new
    subclass.instance_methods(false).each do |meth|
      sub.send(meth) if meth.to_s =~ /^note/
    end
    all_notes += sub.notes
  end
  puts all_notes
end

# use it like this:
class Book < NoteBook
  note "dear diary..." do
    content "no comment"
    footer "seriously, go away. Stop stalking me you pesky book"
  end
end