Script that lists all dependencies of a list of dpkg packages (recursively)

dpkg_dep.rb

#!/usr/bin/env ruby

class DpkgDep
  attr_reader :package_name

  def initialize(package_name)
    @package_name = package_name
  end

  def dependencies_recursive
    deps = dependencies.map { |dep| dep.dependencies_recursive }
    (deps + dependencies).flatten.compact
  end

  def dependencies
    dependencies_raw.map { |package_name| DpkgDep.new(package_name) }
  end

  def size
    `dpkg -s #{@package_name} | grep Installed`.split(' ').last.to_i
  end

  def to_s
    "#{@package_name} #{size}"
  end

  private

  def dependencies_raw
    deps = `dpkg -s #{@package_name} | grep Depends`
    deps = deps.gsub('Depends: ', '')
    deps.scan(/([\d\w\-\.]+)\s+\(/).flatten
  end
end

if $0 == __FILE__
  dependencies = ARGV.collect do |package_name|
    me = DpkgDep.new(package_name)
    [me] + me.dependencies_recursive
  end.flatten

  # Ruby 1.8.7 does not have Array#uniq with block param
  uniq = dependencies.inject(Array.new) do |uniq_deps, item|
    uniq_deps << item unless uniq_deps.any? { |it| it.package_name == item.package_name }
    uniq_deps
  end

  total = uniq.inject(0) do |sum, dependency|
    puts dependency
    sum += dependency.size
  end

  puts "Total: #{total}"
end