Python Argparse 重用属性类型错误 : hasattr(): attribute name must be string

Question

在 Python 2.7 中使用 argparse 我试图通过不重复代码并使用代码进行重用来减少我的代码。在本例中，我尝试重用给予不同子解析器的参数。但是，我收到一个错误，我认为这可能是我尝试调用/分配属性的方式造成的:

import argparse

def create_args():
    parser = argparse.ArgumentParser(description='Transfer file between accounts.'
                                                  'Add/remove tabs and Schemas')
    subparser = parser.add_subparsers(help='Transfer file between acconts')
    transfer = subparser.add_parser('transfer', 
                                     help="Transfer file from 2 accounts")

    add_arguments(transfer, "producer", "consumer",  "uuid")

    return parser


def add_arguments(group, *args):
    options = group.add_argument_group("Switches")

    choices = {  
            "producer" : ('-p',
                          '--producer',
                          'required=True',
                          'help="Producer\'s(source account)"'),
             "consumer" : ('-c',
                           '--consumer',
                           'required=True',
                           'help="Consumer\'s(destination account)"'),
                 "uuid" : ('-u', 
                           '--uuid',
                           'required=True',
                           'help="file ID number"')}
    for arg in args:
        options.add_argument(choices[arg])

<小时/>

   one@dash ~/image_transfer $ python transfer.py transfer
    Traceback (most recent call last):
      File "transfer.py", line 19, in <module>
        start()
      File "transfer.py", line 12, in start
        args = vars(parser.parse_args())
      File "/usr/lib/python2.7/argparse.py", line 1688, in parse_args
        args, argv = self.parse_known_args(args, namespace)
      File "/usr/lib/python2.7/argparse.py", line 1720, in parse_known_args
        namespace, args = self._parse_known_args(args, namespace)
      File "/usr/lib/python2.7/argparse.py", line 1929, in _parse_known_args
        stop_index = consume_positionals(start_index)
      File "/usr/lib/python2.7/argparse.py", line 1885, in consume_positionals
        take_action(action, args)
      File "/usr/lib/python2.7/argparse.py", line 1794, in take_action
        action(self, namespace, argument_values, option_string)
      File "/usr/lib/python2.7/argparse.py", line 1090, in __call__
        namespace, arg_strings = parser.parse_known_args(arg_strings, namespace)
      File "/usr/lib/python2.7/argparse.py", line 1706, in parse_known_args
        if not hasattr(namespace, action.dest):
    TypeError: hasattr(): attribute name must be string

<小时/>

def start():

    parser = create_args()
    args = vars(parser.parse_args())



if __name__ == "__main__":
    start()

Answer 1

您可能想看看这个:

choices = {..
        "producer" : (
            ('-p', '--producer'),
            {'required':True, 'help': "Producer\'s(source account)"}
        ),
        "consumer" : (
            ('-c', '--consumer'),
            {'required':True, 'help': "Consumer\'s(destination account)"}
        ),
        "uuid" : (
            ('-u', '--uuid'),
            {'required':True, 'help': "file ID number"}
        )
}
for arg in args:
    options.add_argument(*choices[arg][0], **choices[arg][1])

add_argument 的方法签名如下所示:

add_argument(name or flags...[, action][, nargs][, const][, default][, type][, choices][, required][, help][, metavar][, dest])

名称或标志部分作为 *args 接收，因此其他所有内容都必须命名。您可以通过使用 **kwargs 扩展字典来传递命名参数。在您的情况下，您传递了一个元组，并且它试图将它(因为它是单个参数)用作名称或标志并出现错误。