ProcString

proc_string.rb

require "forwardable"

class ProcString
  extend Forwardable
  def_delegators :stringified_proc, :to_s, *("".methods - BasicObject.methods)

  attr_reader :proc

  def initialize(&string_proc)
    @proc = string_proc
  end

  def inspect
    "#<#{self.class.name} @proc=#{@proc.inspect} @current_data=#{stringified_proc}>"
  end

  private

  def stringified_proc
    @proc.call.to_s
  end
end

# Example

pstr = ProcString.new { rand }

pstr
=> #<ProcString @proc=#<Proc:0x007f9be580acb8> @current_data=0.7499222574795362>

puts pstr, pstr, pstr
#=> 0.0020494615701293073
#=> 0.8607430906723921
#=> 0.965687955748027

pstr.gsub(/0/,"NULL")
#=> "NULL.2NULL5839749741NULL8NULL55"