From: Carlos Hernandez <carlosjhr64@...>
Date: 2008-01-10T04:17:28+09:00
Subject: Re: Marshal Pipe

class MarshalPipe
  def self.puts(data)
    Marshal.dump(data,$stdout)
  end
  def self.each
    data = nil
    begin
      while data = Marshal.load($stdin) do
        yield data
      end
    rescue EOFError
      # rudely ignore
    end
  end
end


I guess a class/module above is as clean and simple I can get it.
A mp2mp type pipe would be..


require 'marshal_pipe'
MarshalPipe.each { |data|
  transformed_data = transform( data ) # <= do something
  MarshalPipe.puts transformed_data
}


A quick csv2mp could be...


require 'MarshalPipe.rb'
require 'csv'
$stdin.each { |line|
  data = []
  CSV.parse_line( line.strip ).each {|item|
        case item
        when /^-?\d+(\.\d+)?$/
                data.push( ($1)? item.to_f: item.to_i )
        # maybe add date handling or any other data type...
        else
        # simple string
                data.push( item )
        end
  }
  MarshalPipe.puts data
}


and a mp2txt


require 'MarshalPipe.rb'
MarshalPipe.each { |data|
  puts data.join("\t")
}


A hastily written csv2mp needs cat (not knowing how to read files)...

cat source.csv | csv2mp | mp2mp | mp2txt > result.txt

But one could argue to make MarshalPipe a template to make pipes in 
general.
That'd be more like I'm actually using, except
without the much nicer MashalPipe.(puts and each),
-- 
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