Factor out PathDifference into gclient_utils for a later reuse.

trychange.py

 #!/usr/bin/python
 # Copyright (c) 2009 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.
 """Client-side script to send a try job to the try server. It communicates to
 the try server by either writting to a svn repository or by directly connecting
 to the server by HTTP.
 """
 
 import datetime
@@ skipping 409 matching lines @@
                    const=_SendChangeSVN,
                    dest="send_patch",
                    help="Use SVN to talk to the try server")
   group.add_option("--svn_repo",
                    metavar="SVN_URL",
                    help="SVN url to use to write the changes in; --use_svn is "
                         "implied when using --svn_repo")
   parser.add_option_group(group)
 
   options, args = parser.parse_args(argv)
+  if len(args) == 1 and args[0] == 'help':
+    parser.print_help()
 
   # Switch the default accordingly if there was no default send_patch.
   if not options.send_patch:
     if options.port and options.host:
       options.send_patch = _SendChangeHTTP
     elif options.svn_repo:
       options.send_patch = _SendChangeSVN
     else:
       parser.error('Please specify an access method.')
 
-  if len(args) == 1 and args[0] == 'help':
-    parser.print_help()
-  if (not options.files and (not options.issue and options.patchset) and
-      not options.diff and not options.url):
-    # TODO(maruel): It should just try the modified files showing up in a
-    # svn status.
-    parser.error('Nothing to try, changelist is empty.')
-
   try:
     # Convert options.diff into the content of the diff.
     if options.url:
+      if options.files:
+        parser.error('You cannot specify files and --url at the same time.')
       options.diff = urllib.urlopen(options.url).read()
     elif options.diff:
+      if options.files:
+        parser.error('You cannot specify files and --diff at the same time.')
       options.diff = gclient_utils.FileRead(options.diff, 'rb')
     # Process the VCS in any case at least to retrieve the email address.
     try:
       options.scm = GuessVCS(options)
     except NoTryServerAccess, e:
       # If we got the diff, we don't care.
       if not options.diff:
         # TODO(maruel): Raise what?
         raise
 
@@ skipping 16 matching lines @@
       # If no bot is specified, either the default pool will be selected or the
       # try server will refuse the job. Either case we don't need to interfere.
 
     if options.name is None:
       if options.issue:
         options.name = 'Issue %s' % options.issue
       else:
         options.name = 'Unnamed'
         print('Note: use --name NAME to change the try job name.')
     if not options.email:
-      print('Warning: TRYBOT_RESULTS_EMAIL_ADDRESS is not set. Try server '
-            'results might\ngo to: %s@google.com.\n' % options.user)
+      parser.error('Using an anonymous checkout. Please use --email or set '
+                   'the TRYBOT_RESULTS_EMAIL_ADDRESS environment variable.')
     else:
       print('Results will be emailed to: ' + options.email)
 
     # Send the patch.
     options.send_patch(options)
     if not options.dry_run:
       text = 'Patch \'%s\' sent to try server' % options.name
       if options.bot:
         text += ': %s' % ', '.join(options.bot)
       print(text)
   except (InvalidScript, NoTryServerAccess), e:
     if swallow_exception:
       return 1
     print e
     return 1
   return 0
 
 
 if __name__ == "__main__":
   sys.exit(TryChange(None, [], False))