Setting up Python's ArgumentParser with two mutually excluding flags where one flag has optional additional flags -

i define following using python's argumentparser:

--mutually_exclusive_flag_a stringparameter  --mutually_exclusive_flag_b stringparameter     --optional_b_flag_one     --optional_b_flag_two 

one can use either mutually_exclusive_flag_a or mutually_exclusive_flag_b, not both.

if 1 uses mutually_exclusive_flag_b, 1 can use optional_b_flag_one , optional_b_flag_two.

optional_b_flag_one , optional_b_flag_two boolean flags.

i see add_mutally_exclusive_group handle selecting mutually_exclusive_flag_a or mutually_exclusive_flag_b. however, not sure how declare if use mutually_exclusive_flag_b, optional_b_flag_one , optional_b_flag_two valid flags.

it seems may able use subparsers feature , turn mutually_exclusive_flag_a , mutually_exclusive_flag_b commands.

what best option?

argparse can't handle complex of test. mutually exclusive groups can't nested, , don't handle other kinds of logic (only xor, not and , or). i've explored such expansion in python bug/issue, it's not trivial addition.

the best choice own testing after parsing.

the primary purpose of argparse figure out user wants. checking validity, , issuing nice error message plus, not central parsing task.

one of problems expanding mechanism write meaningful usage message general combinations. have thought how you'd explain requirement users?