do_* docstring can cause exn in global -h response [moved]

[trentm]

This is Issue 22 moved from a Google Code project.
Added by 2010-01-27T19:19:17.000Z by [email protected].
Please review that bug for more context and additional comments, but update this bug.

Original labels: Type-Defect, Priority-Medium

Original description

Given:

    def do_foo(self, subcmd, opts):
        """${cmd_usage}

        ${cmd_option_list}
        """
        [...]

"command help foo" works as expected, but "command -h" gives a traceback 
similar to the following:

Traceback (most recent call last):
  File &quot;.\maintain-nightlies.py&quot;, line 27, in <module>
    sys.exit(mn.main())
  File &quot;C:\Users\kjw\AppData\Roaming\Python\Python26\site-packages
\cmdln.py&quot;, line 238, in main
    self.options, args = self.optparser.parse_args(argv[1:])
  File &quot;C:\Python26\lib\optparse.py&quot;, line 1394, in parse_args
    stop = self._process_args(largs, rargs, values)
  File &quot;C:\Python26\lib\optparse.py&quot;, line 1438, in _process_args
    self._process_short_opts(rargs, values)
  File &quot;C:\Python26\lib\optparse.py&quot;, line 1545, in _process_short_opts
    option.process(opt, value, values, self)
  File &quot;C:\Python26\lib\optparse.py&quot;, line 788, in process
    self.action, self.dest, opt, value, values, parser)
  File &quot;C:\Python26\lib\optparse.py&quot;, line 810, in take_action
    parser.print_help()
  File &quot;C:\Users\kjw\AppData\Roaming\Python\Python26\site-packages
\cmdln.py&quot;, line 975, in print_help
    self.cmdln.onecmd([&quot;help&quot;])
  File &quot;C:\Users\kjw\AppData\Roaming\Python\Python26\site-packages
\cmdln.py&quot;, line 412, in onecmd
    return self._dispatch_cmd(handler, argv)
  File &quot;C:\Users\kjw\AppData\Roaming\Python\Python26\site-packages
\cmdln.py&quot;, line 1084, in _dispatch_cmd
    return handler(argv)
  File &quot;C:\Users\kjw\AppData\Roaming\Python\Python26\site-packages
\cmdln.py&quot;, line 517, in do_help
    doc = self._help_preprocess(doc, cmdname)
  File &quot;C:\Users\kjw\AppData\Roaming\Python\Python26\site-packages
\cmdln.py&quot;, line 598, in _help_preprocess
    help = preprocessor(help, cmdname)
  File &quot;C:\Users\kjw\AppData\Roaming\Python\Python26\site-packages
\cmdln.py&quot;, line 739, in _help_preprocess_cmd_usage
    handler = self._get_cmd_handler(cmdname)
  File &quot;C:\Users\kjw\AppData\Roaming\Python\Python26\site-packages
\cmdln.py&quot;, line 865, in _get_cmd_handler
    handler = getattr(self, 'do_' + cmdname)
TypeError: cannot concatenate 'str' and 'NoneType' objects