Wrapping an object that reads in a wrapper you can write to

gistfile1.rb

class ObjectThatInsistsOnCallingRead
  def initialize(io)
    while s = io.read(10)
      print s
    end
  end
end

class WrapperToWhichYouCanWrite
  def initialize
    @read_io, @write_io = IO.pipe
    @thread = Thread.new do
      ObjectThatInsistsOnCallingRead.new(@read_io)
    end
  end

  def write(s)
    @write_io.write(s)
  end

  def close
    @write_io.close.tap do
      @thread.join
    end
  end
end

# using original API
require 'stringio'
io = StringIO.new('bla bla bla')
o = ObjectThatInsistsOnCallingRead.new(io)

# using "push IO"
w = WrapperToWhichYouCanWrite.new

10.times do |i|
  w.write(i.to_s)
end

w.close