Make any File a temporary file

tempify.rb

require 'fileutils'

class File
  def self.finalizer(path)
    lambda do
      FileUtils.rm(path)
    end
  end

  def tempify!
    ObjectSpace.define_finalizer(self, &self.class.finalizer(self.path))
  end
end

10.times do |n|
  File.open("/tmp/blah#{n}.out", "w") do |f|
    puts "This is file #{n+1}"
    f.tempify!
    f.puts "omg"
  end
end