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

native_client_sdk/src/build_tools/dsc_info.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.
 
 """Extracts information from a library.dsc file."""
 
-import optparse
+import argparse
 import os
 import sys
 
 import parse_dsc
 
 def Error(msg):
   print >> sys.stderr, 'dsc_info: %s' % msg
   sys.exit(1)
 
 
 def FindTarget(tree, target_name):
   targets = tree['TARGETS']
   for target in targets:
     if target['NAME'] == target_name:
       return target
   Error('Target %s not found' % target_name)
 
 
 def GetSources(lib_dir, tree, target_name):
   result = []
   target = FindTarget(tree, target_name)
   for filename in target['SOURCES']:
     result.append('/'.join([lib_dir, filename]))
   return result
 
 
-def DoMain(argv):
-  "Entry point for gyp's pymod_do_main command."
-  parser = optparse.OptionParser(usage='%prog: [OPTIONS] TARGET')
+def DoMain(args):
+  """Entry point for gyp's pymod_do_main command."""
+  parser = argparse.ArgumentParser(description=__doc__)
   # Give a clearer error message when this is used as a module.
   parser.prog = 'dsc_info'
-  parser.add_option('-s', '--sources',
+  parser.add_argument('-s', '--sources',
                     help='Print a list of source files for the target',
                     action='store_true', default=False)
-  parser.add_option('-l', '--libdir',
+  parser.add_argument('-l', '--libdir',
                     help='Directory where the library.dsc file is located',
                     metavar='DIR')
-  options, args = parser.parse_args(argv)
-  if len(args) != 1:
-    parser.error('Expecting exactly one argument.')
-  target = args[0]
+  parser.add_argument('target')
+  options = parser.parse_args(args)
   libdir = options.libdir or ''
   tree = parse_dsc.LoadProject(os.path.join(libdir, 'library.dsc'))
   if options.sources:
-    return '\n'.join(GetSources(libdir, tree, target))
+    return '\n'.join(GetSources(libdir, tree, options.target))
   parser.error('No action specified')
 
 
-def main(argv):
-  print DoMain(argv[1:])
+def main(args):
+  print DoMain(args)
 
 
 if __name__ == '__main__':
   try:
-    sys.exit(main(sys.argv))
+    sys.exit(main(sys.argv[1:]))
   except KeyboardInterrupt:
     Error('interrupted')