[NaCl SDK] Convert python scripts from optparse to argparse.

native_client_sdk/src/tools/ncval.py

 #!/usr/bin/env python
 # Copyright 2013 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
-"""Wrapper script for running ncval.
+"""Wrapper script for running the Native Client validator (ncval).
 """
 
-import optparse
+import argparse
 import os
 import subprocess
 import sys
 
 import getos
 
 SCRIPT_DIR = os.path.dirname(os.path.abspath(__file__))
 NACL_SDK_ROOT = os.path.dirname(SCRIPT_DIR)
 
 if sys.version_info < (2, 7, 0):
   sys.stderr.write("python 2.7 or later is required run this script\n")
   sys.exit(1)
 
 class Error(Exception):
   pass
 
 def Log(msg):
   if Log.verbose:
     sys.stderr.write(str(msg) + '\n')
 Log.verbose = False
 
-def main(argv):
-  usage = 'Usage: %prog [options] <.nexe | .so>'
-  epilog = 'Example: ncval.py my_nexe.nexe'
-  parser = optparse.OptionParser(usage, description=__doc__, epilog=epilog)
-  parser.add_option('-v', '--verbose', action='store_true',
-                    help='Verbose output')
+def main(args):
+  parser = argparse.ArgumentParser(description=__doc__)
+  parser.add_argument('-v', '--verbose', action='store_true',
+                      help='Verbose output')
+  parser.add_argument('nexe', metavar="EXE", help='Executable to validate')
 
   # To enable bash completion for this command first install optcomplete
   # and then add this line to your .bashrc:
   #  complete -F _optcomplete ncval.py
   try:
     import optcomplete
     optcomplete.autocomplete(parser)
   except ImportError:
     pass
 
-  options, args = parser.parse_args(argv)
-  if not args:
-    parser.error('No executable file specified')
+  options = parser.parse_args(args)
+  nexe = options.nexe
 
-  nexe = args[0]
   if options.verbose:
     Log.verbose = True
 
   # TODO(binji): http://crbug.com/321791. Fix ncval upstream to reduce the
   # amount of additional checking done here.
   osname = getos.GetPlatform()
   if not os.path.exists(nexe):
     raise Error('executable not found: %s' % nexe)
   if not os.path.isfile(nexe):
     raise Error('not a file: %s' % nexe)
@@ skipping 23 matching lines @@
     # By default, don't print anything on success.
     Log(proc_out)
 
 
 if __name__ == '__main__':
   try:
     sys.exit(main(sys.argv[1:]))
   except Error as e:
     sys.stderr.write(str(e) + '\n')
     sys.exit(1)