argparse:所需组中的一些互斥参数 [英] argparse: some mutually exclusive arguments in required group

问题描述

我有一组可以在逻辑上分为两组的参数:

I have a set of arguments that can logically be separated in 2 groups:

• 动作:A1、A2、A3等
• 信息:I1、I2、I3等

• Actions: A1, A2, A3, etc.
• Informations: I1, I2, I3, etc.

程序启动至少需要这些参数之一，但信息"参数可以与动作"参数一起使用.所以

At least one of these arguments is required for the program to start, but "information" args can be used with "action" args. So

• 至少需要一项操作或信息
• 所有操作都是互斥的

我找不到使用 argparse 的方法.我知道 add_mutually_exclusive_group 及其 required 参数，但我不能在操作"上使用它，因为它实际上不是必需的.当然，我可以在 argparse 之后添加一个条件来手动检查我的规则，但这似乎是一个 hack.argparse 能做到这一点吗?

I can't find how to do it using argparse. I know about add_mutually_exclusive_group and its required argument, but I can't use it on "Actions" because it's not actually required. Of course, I could add a condition after argparse to manually check my rules, but it seems like an hack. Can argparse do this?

抱歉，这里有一些例子.

Sorry, here are some examples.

# Should pass
--A1
--I1
--A1 --I2
--A2 --I1 --I2

# Shouldn't pass
--A1 --A2
--A1 --A2 --I1

推荐答案

在解析参数后验证参数并没有什么不妥.只需将它们全部收集在一个集合中，然后确认它不为空并且最多包含一个操作.

There's nothing hacky about verifying arguments after they've been parsed. Just collect them all in a single set, then confirm that it is not empty and contains at most one action.

actions = {"a1", "a2", "a3"}
informations = {"i1", "i2", "i3"}
p = argparse.ArgumentParser()
# Contents of actions and informations contrived
# to make the example short. You may need a series
# of calls to add_argument to define the options and
# constants properly
for ai in actions + informations:
    p.add_argument("--" + ai, action='append_const', const=ai, dest=infoactions)

args = p.parse_args()
if not args.infoactions:
    p.error("At least one action or information required")
elif len(actions.intersection(args.infoactions)) > 1:
    p.error("At most one action allowed")

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