I don't think this is possible, but I want to handle exceptions from argparse myself.
For example:
import argparse parser = argparse.ArgumentParser() parser.add_argument('--foo', help='foo help', required=True) try: args = parser.parse_args() except: do_something() When I run it:
$ myapp.py usage: myapp --foo foo myapp: error: argument --foo is required But I want it to fall into the exception instead.
You can subclass ArgumentParser and override the error method to do something different when an error occurs:
class ArgumentParserError(Exception): pass class ThrowingArgumentParser(argparse.ArgumentParser): def error(self, message): raise ArgumentParserError(message) parser = ThrowingArgumentParser() parser.add_argument(...) ... 
parser.set_error('too few arguments', method_to_deal_with_error) I suppose I can always file a bug if I want this feature. Thanks!in my case, argparse prints 'too few arguments' then quit. after reading the argparse code, I found it simply calls sys.exit() after printing some message. as sys.exit() does nothing but throws a SystemExit exception, you can just capture this exception.
so try this to see if it works for you.
try: args = parser.parse_args(args) except SystemExit: .... your handler here ... return 
test_argparse.py file uses this approach, along with redefining error to create a ErrorRaisingArgumentParser class.
SystemExitand replacesys.stderrwith some other object.--foooptional? Can you define a custom action to handle it? These may be cleaner actions than overridingargparse's decision to exit.exit_on_errorparameter toArgumentParser(), but it does not (yet?) throw an error for a missing required option nor an unrecognized option. See bugs.python.org/issue41255.