Here are a few examples of extending the optparse module.
First, let's change the option-parsing to be case-insensitive:
from optparse import Option, OptionParser, _match_abbrev # This case-insensitive option parser relies on having a # case-insensitive dictionary type available. Here's one # for Python 2.2. Note that a *real* case-insensitive # dictionary type would also have to implement __new__(), # update(), and setdefault() -- but that's not the point # of this exercise. class caseless_dict (dict): def __setitem__ (self, key, value): dict.__setitem__(self, key.lower(), value) def __getitem__ (self, key): return dict.__getitem__(self, key.lower()) def get (self, key, default=None): return dict.get(self, key.lower()) def has_key (self, key): return dict.has_key(self, key.lower()) class CaselessOptionParser (OptionParser): def _create_option_list (self): self.option_list = [] self._short_opt = caseless_dict() self._long_opt = caseless_dict() self._long_opts = [] self.defaults = {} def _match_long_opt (self, opt): return _match_abbrev(opt.lower(), self._long_opt.keys()) if __name__ == "__main__": from optik.errors import OptionConflictError # test 1: no options to start with parser = CaselessOptionParser() try: parser.add_option("-H", dest="blah") except OptionConflictError: print "ok: got OptionConflictError for -H" else: print "not ok: no conflict between -h and -H" parser.add_option("-f", "--file", dest="file") #print `parser.get_option("-f")` #print `parser.get_option("-F")` #print `parser.get_option("--file")` #print `parser.get_option("--fIlE")` (options, args) = parser.parse_args(["--FiLe", "foo"]) assert options.file == "foo", options.file print "ok: case insensitive long options work" (options, args) = parser.parse_args(["-F", "bar"]) assert options.file == "bar", options.file print "ok: case insensitive short options work"
And two ways of implementing ``required options'' with optparse.
Version 1: Add a method to OptionParser which applications must call after parsing arguments:
import optparse class OptionParser (optparse.OptionParser): def check_required (self, opt): option = self.get_option(opt) # Assumes the option's 'default' is set to None! if getattr(self.values, option.dest) is None: self.error("%s option not supplied" % option) parser = OptionParser() parser.add_option("-v", action="count", dest="verbose") parser.add_option("-f", "--file", default=None) (options, args) = parser.parse_args() print "verbose:", options.verbose print "file:", options.file parser.check_required("-f")
Version 2: Extend Option and add a required attribute; extend OptionParser to ensure that required options are present after parsing:
import optparse class Option (optparse.Option): ATTRS = optparse.Option.ATTRS + ['required'] def _check_required (self): if self.required and not self.takes_value(): raise OptionError( "required flag set for option that doesn't take a value", self) # Make sure _check_required() is called from the constructor! CHECK_METHODS = optparse.Option.CHECK_METHODS + [_check_required] def process (self, opt, value, values, parser): optparse.Option.process(self, opt, value, values, parser) parser.option_seen[self] = 1 class OptionParser (optparse.OptionParser): def _init_parsing_state (self): optparse.OptionParser._init_parsing_state(self) self.option_seen = {} def check_values (self, values, args): for option in self.option_list: if (isinstance(option, Option) and option.required and not self.option_seen.has_key(option)): self.error("%s not supplied" % option) return (values, args) parser = OptionParser(option_list=[ Option("-v", action="count", dest="verbose"), Option("-f", "--file", required=1)]) (options, args) = parser.parse_args() print "verbose:", options.verbose print "file:", options.file