From: "Ara.T.Howard" <Ara.T.Howard@...>
Date: 2005-08-13T00:18:13+09:00
Subject: Re: Re-reading a portion of a source file from a specific point

On Wed, 10 Aug 2005, Berger, Daniel wrote:

> Hi all,
>
>> From within a Ruby program, is there a way to get Ruby to re-read itself
> from a specific part of the file?  Let me explain.  Say I have a method
> "foo".  I would like "foo" to slurp the rest of the script into memory
> and write it to a file, possibly a temp file.
>
> For example:
>
> 1: puts "Hello World"
> 2: foo()
> 3: puts "How's it going?"
>
> In this script I would like lines 2 and 3 (or possibly just line 3 - I'm
> not sure yet), but NOT line 1, read into memory and written to a file
> (by the foo method).  I thought perhaps there were some tricks I could
> use with __DATA__, __END__ or __FILE__, but I wasn't sure.
>
> Any ideas?
>
> Regards,
>
> Dan


one approach:

     harp:~ > cat a.rb
     require 'tempfile'
     require 'stringio'

     def record opts = {}
       getopt =
         lambda do |o|
           catch('opt') do
             [o, o.to_s, o.to_s.intern].each{|k| throw 'opt', opts[k] if opts.has_key? k}
             throw 'opt', nil
           end
         end
       file = getopt['file'] or raise ArgumentError, 'no file'
       a = getopt['start'] or raise ArgumentError, 'no start'
       b = getopt['end'] || -1
       into = getopt['into'] || Tempfile::new(File::basename(file))
       into << IO::readlines(file)[a .. b].join
       into.flush if into.respond_to?('flush')
       into.rewind if into.respond_to?('rewind')
       into
     end

     puts '---'
     tmp = record 'file' => __FILE__, 'start' => __LINE__
     print tmp.read

     puts '---'
     tmp = record 'file' => __FILE__, 'start' => -2, 'end' => -1, 'into' => StringIO::new
     print tmp.read



     harp:~ > ruby a.rb
     ---
     print tmp.read

     puts '---'
     tmp = record 'file' => __FILE__, 'start' => -2, 'end' => -1, 'into' => StringIO::new
     print tmp.read
     ---
     tmp = record 'file' => __FILE__, 'start' => -2, 'end' => -1, 'into' => StringIO::new
     print tmp.read


cheers.

-a
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