From: Michael Morin <uzimonkey@...>
Date: 2008-08-09T06:35:07+09:00
Subject: Re: [QUIZ] hexdump (#171)

Matthew Moss wrote:
> ## hexdump (#171)
> 
> _Quiz idea provided by Robert Dober._
> 
> This week's quiz should be quick and easy for experienced Rubyists,
> and a good lesson for beginners. Your task this week is to write a
> utility that outputs a hex dump of the input.

I did something a little different, I made a module that can be used to 
extend IO objects.  This means you can extend any File or socket objects 
to become hex writers.  Since I don't think you can "un-extend" an 
object, it would probably be best if you dup the IO object if you need 
to switch between hex and normal output.

#!/usr/bin/env ruby
# UziMonkey <uzimonkey@gmail.com>

module HexWriter
   def self.extend_object(o)
     class << o
       alias_method :old_write, :write
     end

     super
   end

   def write(s)
     s.each_byte do|b|
       if @bytes % 16 == 0 and @address != 0
         end_line
         new_line
       end

       write_byte b
     end
   end

   def new_file
     @address = 0
     new_line
   end

   def end_line
     old_write "   " * (16 - @bytes)
     old_write "   #{@ascii}\n"
   end

   def new_line
     @bytes = 0
     @address ||= 0
     @ascii = ""

     old_write "%08x" % @address
   end

   def write_byte(b)
     old_write " %02x" % b

     @ascii << ((b.chr =~ /[[:print:]]/).nil? ? '.' : b.chr)

     @bytes += 1
     @address += 1
   end
end

hex = STDOUT.dup.extend HexWriter
ARGV.each do|f|
   puts "File: #{f}"
   hex.new_file
   hex.write File.read(f)
   hex.end_line
end

-- 
Michael Morin
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