Progress Bars for Ruby's CSV

csv_progress_bar.rb

require 'csv'

# https://rubygems.org/gems/progress_bar
require 'progress_bar'

class CSV
  module ProgressBar
    def progress_bar
      ::ProgressBar.new(@io.size, :bar, :percentage, :elapsed, :eta)
    end

    def each
      progress_bar = self.progress_bar

      super do |row|
        yield row
        progress_bar.count = self.pos
        progress_bar.increment!(0)
      end
    end
  end

  class WithProgressBar < CSV
    include ProgressBar
  end

  def self.with_progress_bar
    WithProgressBar
  end
end

# Usage: Module
data = File.read('data.csv')
csv = CSV.new(data)
csv.extend(CSV::ProgressBar)
csv.each do |row|
  # expensive operation
end

# Usage: Subclass
CSV::WithProgressBar.foreach('data.csv') do |row|
  # expensive operation
end

# Usage: Class Method
CSV.with_progress_bar.foreach('data.csv') do |row|
  # expensive operation
end

More detailed explanation: http://51degrees.net/2012/10/23/progress-bars-for-ruby-csv.html