From: Ruby Newbee <rubynewbee@...>
Date: 2010-01-20T12:08:59+09:00
Subject: help on the dummy module

module ShiftMeansAppend
  def <<(x)  #1
  end
end
class String
  include ShiftMeansAppend
end
class Array
  include ShiftMeansAppend
end
def append_to_self(x)
  unless x.is_a? ShiftMeansAppend  #2
    raise ArgumentError, "I can't trust this object's left-shift operator."
  end
  x << x
end


Hello,

For the code above, I can't understand that:

#1 why redefine "<<" and set its action to nothing?
#2 why x.is_a? ShiftMeansAppend can be true when x is an array or a string?

Thanks.