import argparse

class CustomAction(argparse.Action):

def __init__(self, *args, **kwargs):

argparse.Action.__init__(self, *args, **kwargs)

print("initializing customAction")

for name, value in sorted(locals().items()):

if name == "self" or value is None:

continue

print("\t{} = {!r}".format(name, value))

print()

def __call__(self, parser, namespace, values, option_string=None):

print("Processing customAction for {}".format(self.dest))

print("\tparser = {}".format(id(parser)))

print("\tvalues = {!r}".format(values))

print("\toption_string = {!r}".format(option_string))

if isinstance(values, list):

values = [v.upper() for v in values]

else:

values = values.upper()

setattr(namespace, self.dest, values)

print()

parser = argparse.ArgumentParser()

parser.add_argument("-a", action=CustomAction)

parser.add_argument("-m", nargs="*", action=CustomAction)

results = parser.parse_args(["-a", "value", "-m", "multivalue", "second"])

print(results)