ruby interactive shell that uses `ruby -c`

ruby_c_irb.rb

class TemrinationChecker
  def initialize
    @prelaunched = nil
    @code = ''
    @current = new_session
  end

  def new_session
    IO.popen(['ruby', '-c'], 'r+', err: [:child, :out])
  end

  def session
    @prelaunched ||= new_session
    @current
  end

  def reset_session
    @current.close
    @current = @prelaunched || new_session
    @prelaunched = new_session
    @code = ''
  end

  def check(code)
    verbose, $VERBOSE = $VERBOSE, nil
    begin
      RubyVM::InstructionSequence.compile(code)
      return true
    rescue SyntaxError
    end
    reset_session unless code.start_with? @code
    session.write code.byteslice(@code.bytesize..)
    @code = code
    if session.wait_readable(0.01)
      reset_session
      true
    else
      false
    end
  ensure
    $VERBOSE = verbose
  end
end

checker = TemrinationChecker.new
require 'reline'
loop do
  begin
    input = Reline.readmultiline 'irb> ' do |code|
      checker.check(code)
    end
  rescue Interrupt
    next
  end
  begin
    break unless input
    res = eval(input)
    puts "=> #{res.inspect}"
  rescue SystemExit
    break
  rescue Exception => e
    puts e
    puts e.backtrace
  end
end