self_and_modules_with_constants_breakout.rb

# SELF
class Rat
  def initialize
    @age = 0
  end
  
  def self.run_away
    p "pitter pitter patter"
  end
  
  def age!
    @age += 1
  end
end

rick = Rat.new
# how do you access #run_away? which one works? why? 
# Rat.run_away versus rick.run_away

# how does a rat age? which one works? why? 
# rick.age! versus Rat.age! 

# USING MODULES AND CONSTANTS TOGETHER

# this allows you to use a CONSTANT in the method of a module
# if that class doesn't have that constant, things will break
module CoolActions
  def say_the_thing
    # one way:
    eval("#{self.class}::SPEED")
    # another way:
    # self.class::SPEED
  end
end

class Bats
  SPEED = 123
  
  include CoolActions
end

class Turtles
  include CoolActions
end

test = Bats.new
# why does this work or not work?
test.say_the_thing
# what does this do?
test.methods

# P.S. eval - don't use it. 
# http://stackoverflow.com/questions/1902744/when-is-eval-in-ruby-justified