Arguments that are dependent on other arguments with Argparse

Question

I want to accomplish something like this:

-LoadFiles     -SourceFile "" -DestPath ""     -SourceFolder "" -DestPath "" -GenericOperation     -SpecificOperation -Arga "" -Argb ""     -OtherOperation -Argc "" -Argb "" -Argc "" 

A user should be able to run things like:

-LoadFiles -SourceFile "somePath" -DestPath "somePath" 

or

-LoadFiles -SourceFolder "somePath" -DestPath "somePath" 

Basically, if you have -LoadFiles, you are required to have either -SourceFile or -SourceFolder after. If you have -SourceFile, you are required to have -DestPath, etc.

Is this chain of required arguments for other arguments possible? If not, can I at least do something like, if you have -SourceFile, you MUST have -DestPath?

Answer 1

You can use subparsers in argparse

 import argparse  parser = argparse.ArgumentParser(prog='PROG')  parser.add_argument('--foo', required=True, help='foo help')  subparsers = parser.add_subparsers(help='sub-command help')   # create the parser for the "bar" command  parser_a = subparsers.add_parser('bar', help='a help')  parser_a.add_argument('bar', type=int, help='bar help')  print(parser.parse_args()) 

Answer 2

After you call parse_args on the ArgumentParser instance you've created, it'll give you a Namespace object. Simply check that if one of the arguments is present then the other one has to be there too. Like:

args = parser.parse_args() if ('LoadFiles' in vars(args) and      'SourceFolder' not in vars(args) and      'SourceFile' not in vars(args)):      parser.error('The -LoadFiles argument requires the -SourceFolder or -SourceFile')