From: "trans.  (T. Onoma)" <transami@...>
Date: 2004-12-28T04:31:31+09:00
Subject: split on '' (and another for split -1)

Here's a generic routine I'm working on:

  class String
    def last=(str, separator=$/)
      separator = '' unless separator
      raise "separator must be a String" unless String === separator
      s = self.split(separator, -1)
      s[-1] = str
      self.replace(s.join(separator))
    end
  end

  $/ = "\n"
  s = "ab\nc"
  s.last = "123"
  p s
  # => "ab\n123"

Now try:

  $/ = ""
  s = "abc"
  s.last = "123"
  p s

Unfortunately this does not give a congruent result. 

As an aside, this relates to the split -1 since any generic routine will not 
know what the split separator is and therefore will require the -1. Though my 
analysis is not complete, I continue to find that in most cases the -1 
parameter is either required, or at worst, inconsequential.

T.