roll_dep.py: switch to argparse

roll_dep.py

 #!/usr/bin/env python
 # Copyright 2015 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.
 
 """Rolls DEPS controlled dependency.
 
-Works only with git checkout and git dependencies.
+Works only with git checkout and git dependencies.  Currently this
+script will always roll to the tip of to origin/master.
 """
 
-import optparse
+import argparse
 import os
 import re
 import subprocess
 import sys
 
 NEED_SHELL = sys.platform.startswith('win')
 
 
 class Error(Exception):
   pass
@@ skipping 24 matching lines @@
     with open(deps, 'rb') as f:
       deps_content = f.read()
   except (IOError, OSError):
     raise Error('Ensure the script is run in the directory '
                 'containing DEPS file.')
 
   if not is_pristine(root):
     raise Error('Ensure %s is clean first.' % root)
 
   full_dir = os.path.normpath(os.path.join(os.path.dirname(root), deps_dir))
+  if not os.path.isdir(full_dir):
+    raise Error('Directory not found: %s' % deps_dir)
   head = check_output(['git', 'rev-parse', 'HEAD'], cwd=full_dir).strip()
 
   if not head in deps_content:
     print('Warning: %s is not checked out at the expected revision in DEPS' %
           deps_dir)
     if key is None:
       print("Warning: no key specified.  Using '%s'." % deps_dir)
       key = deps_dir
 
     # It happens if the user checked out a branch in the dependency by himself.
@@ skipping 49 matching lines @@
   print('')
   if not reviewers:
     print('You forgot to pass -r, make sure to insert a R=foo@example.com line')
     print('to the commit description before emailing.')
     print('')
   print('Run:')
   print('  git cl upload --send-mail')
 
 
 def main():
-  parser = optparse.OptionParser(
-      description=sys.modules[__name__].__doc__,
-      usage='roll-dep [flags] <dependency path> <variable>')
-  parser.add_option(
-      '-r', '--reviewer', default='',
+  parser = argparse.ArgumentParser(description=__doc__)
+  parser.add_argument('-r', '--reviewer',
       help='To specify multiple reviewers, use comma separated list, e.g. '
            '-r joe,jane,john. Defaults to @chromium.org')
-  parser.add_option('-b', '--bug', default='')
-  options, args = parser.parse_args()
-  if not len(args) or len(args) > 2:
-    parser.error('Expect one or two arguments' % args)
+  parser.add_argument('-b', '--bug')
+  parser.add_argument('dep_path', help='path to dependency')
+  parser.add_argument('key', nargs='?',
+      help='regexp for dependency in DEPS file')
+  args = parser.parse_args()
 
   reviewers = None
-  if options.reviewer:
-    reviewers = options.reviewer.split(',')
+  if args.reviewer:
+    reviewers = args.reviewer.split(',')
     for i, r in enumerate(reviewers):
       if not '@' in r:
         reviewers[i] = r + '@chromium.org'
 
   try:
     roll(
         os.getcwd(),
-        deps_dir=args[0],
-        key=args[1] if len(args) > 1 else None,
+        args.dep_path,
+        args.key,
         reviewers=reviewers,
-        bug=options.bug)
+        bug=args.bug)
 
   except Error as e:
     sys.stderr.write('error: %s\n' % e)
     return 1
 
   return 0
 
 
 if __name__ == '__main__':
   sys.exit(main())