Python argparse检查是否存在标志，同时还允许参数 [英] Python argparse check if flag is present while also allowing an argument

问题描述

如何检查标志--load是否存在?

How do I check if the flag --load is present?

#!/usr/bin/env python3
import argparse
import os 

parser = argparse.ArgumentParser(description='Process some integers.')
parser.add_argument('-l', '--load', nargs='?', metavar='path', help='Load all JSON files recursively in path')

args = parser.parse_args()

print(args)

使用--load调用脚本将输出以下内容: Namespace(load=None)

Calling the script with --load outputs the following: Namespace(load=None)

我不能省略nargs='?'并使用action='store_true'，因为我想允许传递参数，例如--load abcxyz.

I can't omit nargs='?' and use action='store_true' as I'd like to allow an argument to be passed, for example --load abcxyz.

添加action='store_true'和nargs='?'会产生以下错误:

Adding action='store_true'and nargs='?' produces an error of:

    parser.add_argument('-l', '--load', nargs='?', metavar='path', help='Load all JSON files recursively in path', action='store_true')
  File "/usr/lib/python3.6/argparse.py", line 1334, in add_argument
    action = action_class(**kwargs)
TypeError: __init__() got an unexpected keyword argument 'nargs'

推荐答案

在上述片段中，用于检查--load标志:

In the same above snippet, for checking --load flag:

#!/usr/bin/env python3
import argparse
import os
name = None
parser = argparse.ArgumentParser(description='Process some integers.')
parser.add_argument('-l', '--load', metavar='path', help='Load all JSON 
files recursively in path')

args = parser.parse_args()

print(args.load)

if args.load:
    name = args.load

将name分配给abcxyz，否则将为空. 如果我能够理解您的问题，那么上面的代码实际上可以满足您的需求. name变量并不是真正需要的，仅作为示例.

will assign name to abcxyz, else will be none. If i am able to understand your problem, the above code actually does what you are looking for. The name variable is not really required , just used as an example.

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