dc_open3.rb

#http://github.com/ahoward/open4 is an alternative that handles pid and exit status
#http://github.com/ahoward/session a more fleshed our shell utility
require 'open3'
 
Open3.popen3("dc") do |stdin, stdout, stderr|
  t = Thread.new(stderr) do |terr|
    while (line = terr.gets)
      puts "stderr: #{line}"
    end
  end
  
  puts "pushing 5 to stack"
  stdin.puts(5)
  puts "pushing 10 to stack"
  stdin.puts(10)
  puts "pushing + to stack"
  stdin.puts("+")
  puts "sending print command"
  stdin.puts("p")
  result = stdout.gets
  puts "stdout: #{ result }"
  
  puts "\ntrying an unsupported command"
  stdin.puts("b")


  extra_info_not_in_stderror = stdout.gets
  puts "stdout: #{extra_info_not_in_stderror}"

 
  puts "\nclosing stdin to avoid deadlock with stderr"
  stdin.close

  # puts "let's give stderr a chance to run"
  # t.run or sleep 1
  
  puts "joining"
  t.join
end