optparse code to argparse¶The argparse module offers several higher level features not natively
provided by the optparse module, including:
Handling positional arguments.
Supporting subcommands.
Allowing alternative option prefixes like + and /.
Handling zero-or-more and one-or-more style arguments.
Producing more informative usage messages.
Providing a much simpler interface for custom type and action.
Originally, the argparse module attempted to maintain compatibility
with optparse. However, the fundamental design differences between
supporting declarative command line option processing (while leaving positional
argument processing to application code), and supporting both named options
and positional arguments in the declarative interface mean that the
API has diverged from that of optparse over time.
As described in Choosing an argument parsing library, applications that are
currently using optparse and are happy with the way it works can
just continue to use optparse.
Application developers that are considering migrating should also review the list of intrinsic behavioural differences described in that section before deciding whether or not migration is desirable.
For applications that do choose to migrate from optparse to argparse,
the following suggestions should be helpful:
Replace all optparse.OptionParser.add_option() calls with
ArgumentParser.add_argument() calls.
Replace (options, args) = parser.parse_args() with args =
parser.parse_args() and add additional ArgumentParser.add_argument()
calls for the positional arguments. Keep in mind that what was previously
called options, now in the argparse context is called args.
Replace optparse.OptionParser.disable_interspersed_args()
by using parse_intermixed_args() instead of
parse_args().
Replace callback actions and the callback_* keyword arguments with
type or action arguments.
Replace string names for type keyword arguments with the corresponding
type objects (e.g. int, float, complex, etc).
Replace optparse.Values with Namespace and
optparse.OptionError and optparse.OptionValueError with
ArgumentError.
Replace strings with implicit arguments such as %default or %prog with
the standard Python syntax to use dictionaries to format strings, that is,
%(default)s and %(prog)s.
Replace the OptionParser constructor version argument with a call to
parser.add_argument('--version', action='version', version='<the version>').