Python Argparse有条件的必需参数

问题描述

我已经进行了尽可能多的研究，但是我还没有找到仅在特定条件下才需要某些cmdline参数的最佳方法，在这种情况下，只有给出了其他参数.这是我最基本的操作:

I have done as much research as possible but I haven't found the best way to make certain cmdline arguments necessary only under certain conditions, in this case only if other arguments have been given. Here's what I want to do at a very basic level:

p = argparse.ArgumentParser(description='...')
p.add_argument('--argument', required=False)
p.add_argument('-a', required=False) # only required if --argument is given
p.add_argument('-b', required=False) # only required if --argument is given

从我所见，其他人似乎只是在末尾添加自己的支票:

From what I have seen, other people seem to just add their own check at the end:

if args.argument and (args.a is None or args.b is None):
    # raise argparse error here

是否可以在argparse软件包中本地执行此操作?

Is there a way to do this natively within the argparse package?

推荐答案

一段时间以来，我一直在寻找这种问题的简单答案.您需要做的就是检查'--argument'是否在sys.argv中，因此基本上对于您的代码示例，您可以这样做:

I've been searching for a simple answer to this kind of question for some time. All you need to do is check if '--argument' is in sys.argv, so basically for your code sample you could just do:

import argparse
import sys

if __name__ == '__main__':
    p = argparse.ArgumentParser(description='...')
    p.add_argument('--argument', required=False)
    p.add_argument('-a', required='--argument' in sys.argv) #only required if --argument is given
    p.add_argument('-b', required='--argument' in sys.argv) #only required if --argument is given
    args = p.parse_args()

这种方式required接收True或False取决于用户是否使用过--argument.已经进行了测试，似乎可以正常工作，并保证-a和-b在彼此之间具有独立的行为.

This way required receives either True or False depending on whether the user as used --argument. Already tested it, seems to work and guarantees that -a and -b have an independent behavior between each other.

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