ruby class machanism example 1

gistfile1.rb

class Sth
  def present
    raise NotImplementedError
  end

  def log s
    puts s
  end
end

class Person < Sth
  def eat sth
    if self.can_eat > sth.size
      log "#{self.present} is eating #{sth.present} with size #{sth.size},"
      self.can_eat -= sth.size
      log "#{self.represent} can eat more #{self.can_eat}"
    else
      log "#{self.present} is trying to eat #{sth.present} with size #{sth.size},"
      log "but #{self.represent} cannot eat more."
    end
  end

  def can_eat
    @eat_size ||= (rand * 5 + 3).to_i
  end

  def can_eat= size
    @eat_size = size
  end

end

class Person
  def initialize attrs
    @attrs = attrs
    @attrs[:gender] ||= :male
  end

  def represent
    case @attrs[:gender] 
    when :male   then "he" 
    when :female then "she"
    else "it"
    end
  end

  def present
    @attrs[:name]
  end
end

class Apple < Sth
  attr_reader :size

  def initialize
    @size = (rand * 4 + 1).to_i
  end

  def present
    "apple"
  end
end


me = Person.new name: "halida"
apples = 12.times.map{Apple.new}
apples.each {|apple| me.eat apple}