在python中解析参数 [英] parsing argument in python

问题描述

我在寻找解决方案时遇到问题.我不确定是否可以使用argparse做到这一点.

I have a problem I am trying to find a solution. I am not sure if I can do it with argparse.

我希望能够指定一个选项

I want to be able to specify an option

myprog -a 1
myprog -a 2

现在，当我有 a = 1 时，我希望能够指定 b 和 c .但是当 a = 2 时，我只能指定 d .

Now when I have a = 1, I want to be able to specify b and c. But when a = 2, I can only specify d.

myprog -a 1 -b 3 -c 0
myprog -a 2 -d 3

还必须始终指定 a

推荐答案

您不能将开关值作为单个parse_args调用来执行此操作，但是您可以执行以下操作之一:

You can't do this with switched values as a single parse_args call, but you can do one of:

1. 使用子命令/子解析器
2. 在完全配置解析器并在完整的命令行上运行之前，请先进行部分解析，首先仅检查a，然后根据首次调用的结果选择要解析的其他解析器args.诀窍是首先使用 parse_known_args 调用，因此它处理a(它可以识别)并忽略其他所有内容.

1. Use sub-commands/sub-parsers
2. Do partial parsing before fully configuring the parser and running on the complete command line, at first only checking for a, and then selecting the additional parser args to parse based on the result of the first call. The trick is to use parse_known_args for the first call, so it handles a (which it recognizes) and ignores everything else.

例如，对于方法2，您可以执行以下操作:

For example, for approach #2, you could do:

parser = argparse.ArgumentParser()
parser.add_argument('-a', required=True, type=int, choices=(1, 2)
args = parser.parse_known_args()

if args.a == 1:
    parser.add_argument('-b', ...)
    parser.add_argument('-c', ...)    
    args = parser.parse_args()
else:
    parser.add_argument('-d', ...)
    args = parser.parse_args()

这种方法的缺点是，由于不正确的用法而吐出的用法信息将是不完整的.您必须手动在基本解析器中包含指定真实"用法的文本，这很无聊.不能基于值开关来切换子解析器，但是它们具有统一的，一致的用法显示.

Downside to this approach is that the usage info spat out for incorrect usage will be incomplete; you'd have to include the text specifying the "real" usage in the base parser manually, which is no fun. Subparsers can't be toggled based on value switches, but they have a unified, coherent usage display.

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