random test. # I wanted to try and flush the string before it dies. note that ruby only has a finalizer , it does not have a destructor. I could have use ObjectSpace.define_finalizer self, proc {persist} and use GC.start at the command line to run the garbage collector however it would be after destroying an instance object.

gistfile1.rb

#persistent_string.rb
class PersistentString < String
  def initialize data= nil
    @@count ||= 0
    load data #ObjectSpace.define_finalizer self, proc {persist}
    super
  end
 
  #Instance Methods
 
  def get_length 
    data.length
  end
 
  def is_palindrome 
    unless data.split.join.downcase.eql? data.split.join.downcase.reverse #split.join in case the string has \n
      puts "The string provided is not a palindrome" 
    else
      puts "The string provided is a palindrome" 
    end
 end
  
  private
 
  attr_accessor :data
 
  def load data
    if data.nil? 
      raise ArgumentError, "no data was provided"
    else
      self.data = data.to_s
      puts "data successfully loaded"
      persist
    end
  end
 
  def persist
    File.open "file_#{@@count}.out", 'w+' do |f|
      f.puts "#{data}"
    end
    puts "data entered: #{data}\nfilename: file_#{@@count}.out"
    @@count += 1
  end
 
  public
 
  #Class methods
  
  class << PersistentString
    def read_to file
      begin
        return STDOUT.puts File.read(file.to_s) if File.exist? file  
      rescue Exception => e
        return error_message(e)
      end
      error_message
    end
 
    def append_to file
      begin
        if File.exist? file 
          File.open(file.to_s, 'a') do |f|
            puts "Enter data: "
            f.write STDIN.gets
          end
        else
          error_message
        end 
      rescue Exception => e 
        error_message(e)
      end
    end
 
    private
 
    def error_message(e=nil, incomplete=nil)
      STDERR.puts "A dramatic error occured! verify that the file exists"
      STDERR.puts "More info about the error: #{e.message}" if e
    end
  end
end

#This is an example on how the class could be used


2.0.0-p247 :004 > temp = PersistentString.new "This is the beginning"
data successfully loaded
data entered: This is the beginning
filename: file_0.out
 => "This is the beginning" 

2.0.0-p247 :005 > temp.get_length
 => 21 

2.0.0-p247 :006 > temp.is_palindrome
The string provided is not a palindrome
 => nil 

2.0.0-p247 :007 > temp2 = PersistentString.new "This is another random String"
data successfully loaded
data entered: This is another random String
filename: file_1.out

2.0.0-p247 :011 > temp2.index('a')
 => 8 
2.0.0-p247 :012 > temp2[8..-1] = "the beginning"
 => "the beginning" 

2.0.0-p247 :013 > temp2
 => "This is the beginning" 
2.0.0-p247 :014 > temp == temp2
 => true 

2.0.0-p247 :015 > PersistentString.read_to [123]
A dramatic error occured! verify that the file exists
More info about the error: no implicit conversion of Array into String
 => nil 

2.0.0-p247 :016 > PersistentString.read_to "file_0.out"
This is the beginning
 => nil 

2.0.0-p247 :017 > PersistentString.read_to "file_dont_exist"
A dramatic error occured! verify that the file exists
 => nil 

2.0.0-p247 :018 > PersistentString.append_to "file_dont_exist"
A dramatic error occured! verify that the file exists
 => nil 

2.0.0-p247 :019 > PersistentString.append_to "file_0.out"
Enter data: 
THis is the end
 => 16 

2.0.0-p247 :020 > PersistentString.read_to "file_0.out"
This is the beginning
THis is the end
 => nil