From: Jacob Rubynovice <l33tb0y@...>
Date: 2008-05-30T00:30:45+09:00
Subject: How can a code block access an object's variables?

Dear Rubyists,

I am a novice Ruby developer who is interested in figuring out a way to
design something like what is demonstrated below.  The reason why
each_line would not work in this example is because when you pass a
block of code to the FileReader object, the memory (members of
FileReader) is not shared with the block of code that is sent to
FileReader.

Maybe I have the wrong idea for how this would be designed.  I just
think it would be very convenient to do this sort of thing because I
could re-use the code to open a file and read lines and only pass it
code blocks pertainant to what I want to do with those lines of code.

Please note that I do not only want to do this for an open file/read
line script.  It would also be useful if you were expanding an IP range
that exceeds what you could store into an array object because you could
write an each_host method that takes in a block of code that relates to
what you want to do to each host.

class FileReader

   def initialize(fname, &block)
     @filename = fname
   end
   def each_line(&block)
     begin
       source = File.new(@filename, "r")
     rescue => err
       exit
     end
     begin
       while(line = source.readline)

         line.strip!
         if((line == "") || (line =~ /[\t+\s+]/))
           next
         end
         block.call
       end
     rescue EOFError
       source.close
     rescue => err
       puts "[!] #{err}"
       exit
     end
   end

end
my_reader = FileReader.new(ARGV[0])
my_reader.each_line { puts line
    # do more parsing stuff here
 }
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