File IO for vm translator

vmtranslator.rb

begin
  raise VMTranslatorError.new("Only enter the name of one .vm file or the name of a directory") if ARGV.length > 1
  raise VMTranslatorError.new("File does not exist") unless File.exists?(ARGV.first)
  
  if File.directory? ARGV.first
    files = Dir.glob(File.join(ARGV.first, '*.vm'))
    raise VMTranslatorError.new("No .vm files in #{ARGV.first}") unless files.length > 0
    outfile = File.join(ARGV.first, File.basename(ARGV.first))
  else
    raise VMTranslatorError.new("Not a .vm file") unless ARGV.first =~ /\A(.+)\.vm\Z/i
    files = [ARGV.first]
    outfile = $1
  end
  
  program = VMProgram.new
  files.each do |a|
    open(a) do |infile|
      program.add_class(File.basename(a, '.vm'), infile.read)
    end
  end
  
  open("#{outfile}.asm", 'w') do |outfile|
    outfile.write(program.to_asm)
  end
rescue VMTranslatorError => e
  puts "Virtual machine translator error\n#{e}"
  exit(1)
end