[Twisted-Python] twisted.python.usage.Options Questions

[Justin Johnson]

Greetings,

I'm using twisted.python.usage to handle command-line option parsing. 
The script I have uses subcommands, so I can type:

myscript.py subcommand -a 1 -b 2 ...

I sub-classed BaseOptions as follows...

[code]
# Setup command-line options for all subcommands
class BaseOptions(usage.Options):
	optFlags = [
		['help', 'h', "Display usage information"],
	]

class MkvobOptions(BaseOptions):
	optParameters = [
		['vobs', 'v', None, "Comma-delimited list of VOBs to create"],
		['original', 'o', None, "Original site to create VOBs at first"],
        ['sites', 's', None, "Comma-delimited list of sites to replicate
        to"],
		['group', 'g', r'UHCADAAA\ccusers', "NT group to be primary group for VOBs"]
	]
	def postOptions(self):
		for opt in ["vobs","original"]:
			if not self[opt]:
				raise usage.UsageError, "--vobs and --original are required."

class RmvobOptions(BaseOptions):
	optParameters = [
		['vobs', 'v', None, "Comma-delimited list of VOBs to remove"],
		['original', 'o', None, "Site to remove VOBs from"],
	]
	def postOptions(self):
		for opt in ["vobs","original"]:
			if not self[opt]:
				raise usage.UsageError, "--vobs and --original are required."

class Options(usage.Options):
	subCommands = [
		['mkvob', None, MkvobOptions, "Create VOBs"],
		['rmvob', None, RmvobOptions, "Remove VOBs"]
	]
[/code]

I have some questions though.

1)  Passing in the --help option displays usage info the way I'd want it,
grabbing __doc__ from the top of the file and also displaying info about
my subcommands.  

[output]
C:\share\python\uhg\uht\tsd\ClearCase>vobtool.py --help
Usage: vobtool.py [options]
Options:
      --version
      --help     Display this help and exit.

VOB Administrative Tool  <<< This is my __doc__

Commands:
    mkvob      Create VOBs
    rmvob      Remove VOBs


C:\share\python\uhg\uht\tsd\ClearCase>
[/output]

But when I pass the --help option to a subcommand, I'd like to have some
sort of __doc__ equivalent for the subcommand, but I get the following
instead.

[output]
C:\share\python\uhg\uht\tsd\ClearCase>vobtool.py mkvob --help
Usage: vobtool.py [options]
Options:
  -h, --help       Display this help and exit.
  -v, --vobs=      Comma-delimited list of VOBs to create
  -o, --original=  Original site to create VOBs at first
  -s, --sites=     Comma-delimited list of sites to replicate to
  -g, --group=     NT group to be primary group for VOBs [default:
                   UHCADAAA\ccusers]
      --version

VOB Administrative Tool  <<< The __doc__ for the file
[/output]

Is there a way to do that?

2)  When I just run the command without passing any options (not even a
subcommand) I get the following error:

[output]
C:\share\python\uhg\uht\tsd\ClearCase>vobtool.py
Traceback (most recent call last):
  File "C:\share\python\uhg\uht\tsd\ClearCase\vobtool.py", line 121, in ?
    main()
  File "C:\share\python\uhg\uht\tsd\ClearCase\vobtool.py", line 55, in
  main
    if config.subCommand == 'mkvob':
  File "C:\Python22\Lib\site-packages\twisted\python\usage.py", line 151,
  in __g
etattr__
    raise AttributeError("%s instance has no attribute '%s'" %
    (self.__class__,
attr))
AttributeError: __main__.Options instance has no attribute 'subCommand'

C:\share\python\uhg\uht\tsd\ClearCase>
[/output]

My main function is as follows...

[snip]
# Main function
def main():
	config = Options()
	try:
		config.parseOptions()
	except usage.UsageError, errortext:
		print '%s: %s' % (sys.argv[0], errortext)
		print '%s: Try --help for usage details.' % (sys.argv[0])
		sys.exit(1)

	if config.subCommand == 'mkvob':
		doMkvob(config.subOptions)
	elif config.subCommand == 'rmvob':
		doRmvob(config.subOptions)
[snip]

Is there a particular test I should do on config before checking
config.subCommand?

3)  I see there is a --version option available if you use
twisted.python.usage.  But it always displays the Twisted version.  Is
there a way to override that so the --version option either isn't
available or at least returns the version information for my script and
not for Twisted?


Sorry for the long email.
Thanks so much.
-Justin