argparse

I have a script where I ask the user for a list of pre-defined actions to perform. I also want the ability to assume a particular list of actions when the user doesn't define anything. however, it seems like trying to do both of these together is impossible. when the user gives no arguments, they receive an error that the default choice is invalid acts = ['clear','copy','dump','lock'] p = argparse.ArgumentParser() p.add_argument('action', nargs='*', action='append', choices=acts, default=[['dump', 'clear']]) args = p.parse_args([]) >>> usage: [-h] [{clear,copy,dump,lock} [{clear,copy,dump,lock

Does argparse provide built-in facilities for having it parse groups or parsers into their own namespaces? I feel like I must be missing an option somewhere. Edit : This example is probably not exactly what I should be doing to structure the parser to meet my goal, but it was what I worked out so far. My specific goal is to be able to give subparsers groups of options that are parsed into namespace fields. The idea I had with parent was simply to use common options for this same purpose. Example: import argparse # Main parser main_parser = argparse.ArgumentParser() main_parser.add_argument("

I have tested optcomplete working with the optparse module. Its example is a simple file so I could get that working. I also tested it using the argparse module as the prior one is deprecated. But I really do not understand how and by whom the python program gets called on tab presses. I suspect bash together with the shebang line and the argparse (or optparse ) module are involved in some way. I have been trying to figure this out (now gonna read the source code). I have a little more complex program structure, which includes a wrapper around the piece of code which handles the arguments. Its

I'm trying to write a script that accepts multiple input sources and does something to each one. Something like this ./my_script.py \ -i input1_url input1_name input1_other_var \ -i input2_url input2_name input2_other_var \ -i input3_url input3_name # notice inputX_other_var is optional But I can't quite figure out how to do this using argparse . It seems that it's set up so that each option flag can only be used once. I know how to associate multiple arguments with a single option ( nargs='*' or nargs='+' ), but that still won't let me use the -i flag multiple times. How do I go about

I have a script which has certain options that can either be passed on the command line, or from environment variables. The CLI should take precedence if both are present, and an error occur if neither are set. I could check that the option is assigned after parsing, but I prefer to let argparse to do the heavy lifting and be responsible for displaying the usage statement if parsing fails. I have come up with a couple of alternative approaches to this (which I will post below as answers so they can be discussed separately) but they feel pretty kludgey to me and I think that I am missing

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

I thought that nargs='*' was enough to handle a variable number of arguments. Apparently it's not, and I don't understand the cause of this error. The code: p = argparse.ArgumentParser() p.add_argument('pos') p.add_argument('foo') p.add_argument('--spam', default=24, type=int, dest='spam') p.add_argument('vars', nargs='*') p.parse_args('1 2 --spam 8 8 9'.split()) I think the resulting namespace should be Namespace(pos='1', foo='2', spam='8', vars=['8', '9']) . Instead, argparse gives this error: usage: prog.py [-h] [--spam SPAM] pos foo [vars [vars ...]] error: unrecognized arguments: 9 8