Upgrading optparse code¶

Originally, theargparse module had attempted to maintain compatibilitywithoptparse. However,optparse was difficult to extendtransparently, particularly with the changes required to supportnargs= specifiers and better usage messages. When most everything inoptparse had either been copy-pasted over or monkey-patched, it nolonger seemed practical to try to maintain the backwards compatibility.

Theargparse module improves on theoptparsemodule in a number of ways 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 customtype andaction.

A partial upgrade path fromoptparse toargparse:

• Replace alloptparse.OptionParser.add_option() calls withArgumentParser.add_argument() calls.

• Replace(options,args)=parser.parse_args() withargs=parser.parse_args() and add additionalArgumentParser.add_argument()calls for the positional arguments. Keep in mind that what was previouslycalledoptions, now in theargparse context is calledargs.

• Replaceoptparse.OptionParser.disable_interspersed_args()by usingparse_intermixed_args() instead ofparse_args().

• Replace callback actions and thecallback_* keyword arguments withtype oraction arguments.

• Replace string names fortype keyword arguments with the correspondingtype objects (e.g. int, float, complex, etc).

• Replaceoptparse.Values withNamespace andoptparse.OptionError andoptparse.OptionValueError withArgumentError.

• Replace strings with implicit arguments such as%default or%prog withthe standard Python syntax to use dictionaries to format strings, that is,%(default)s and%(prog)s.

• Replace the OptionParser constructorversion argument with a call toparser.add_argument('--version',action='version',version='<theversion>').