The evil of including Modules globally. Stop it people!

include_object.rb

module A
  class C
    def initialize
      @foo = 'lame'
      @boo = 'boo'
    end
    def bar
      foo # wait, foo is not defined in C?! wait for it...
    end
    def baz
      boo # wait boo is not defined in C! wait for it... (hint: private method)
    end
  end # class C
  # a typo.. foo was meant to be in C
  def foo
    @foo
  end
end # module A


# but library decides to pollute Object by including A in global namespace...
include A

# defining foo in Object (Object#foo). 
# same as including a Module in global namespace. 
# all subclasses of Object now get these methods... including C!
def boo
  @boo
end

c = A::C.new  

# these still works... awesome?
c.bar # lame
c.baz # boo  


class B; end
B.new.respond_to? :foo  # => true. wtf?!!
B.new.boo # private method error...