Python argparse 第二选择

Question

通过使用 Python argparse 模块，我目前有这个：

usage: prog [-h] (-a {opt1,opt2} | -b {opt3,opt4}) arg.

但是，我想实现以下（选项-a的第二组选择）：

usage: prog [-h] (-a {opt1,opt2} {opt5,opt6} | -b {opt3,opt4}) arg.

我不知道该怎么做。有帮助吗？

Answer 1

这个有效：

import argparse

class MultichoiceArgumentParser(argparse.ArgumentParser):
    def _get_values(self, action, arg_strings):
        if isinstance(action.nargs, int):
            value = [self._get_value(action, v) for v in arg_strings]
            for i, v in enumerate(value):
                self._check_value(action, v, arg_num=i)
            return value
        else:
            return super()._get_values(action, arg_strings)

    def _check_value(self, action, value, arg_num=None):
        # converted value must be one of the choices (if specified)
        if action.choices is not None:
            choices = action.choices
            if isinstance(action, MultichoiceAction):
                choices = choices[arg_num]
            if value not in choices:
                args = {'value': value,
                        'choices': ', '.join(map(repr, choices))}
                msg = argparse._('invalid choice: %(value)r (choose from %(choices)s)')
                raise argparse.ArgumentError(action, msg % args)

class MultichoiceAction(argparse._StoreAction):
    pass

class MultichoiceFormatter(argparse.HelpFormatter):
    def _metavar_formatter(self, action, default_metavar):
        if action.choices is not None and isinstance(action, MultichoiceAction):
            result = []
            for choices in action.choices:
                choice_strs = [str(choice) for choice in choices]
                result.append('{%s}' % ','.join(choice_strs))
            result = tuple(result)
            return lambda x: result
        else:
            return super()._metavar_formatter(action, default_metavar)

要使用它：

parser = MultichoiceArgumentParser(formatter_class=MultichoiceFormatter)
parser.add_argument("-a", choices=["ABC", "XYZ"], nargs=2, action=MultichoiceAction)
print(parser.parse_args())

正在使用：

$ python d2.py -h
usage: d2.py [-h] [-a {A,B,C} {X,Y,Z}]

optional arguments:
  -h, --help          show this help message and exit
  -a {A,B,C} {X,Y,Z}

$ python d2.py -a A X
Namespace(a=['A', 'X'])

$ python d2.py -a C Y
Namespace(a=['C', 'Y'])

$ python d2.py -a B Z
Namespace(a=['B', 'Z'])

$ python d2.py -a B B
usage: d2.py [-h] [-a {A,B,C} {X,Y,Z}]
d2.py: error: argument -a: invalid choice: 'B' (choose from 'X', 'Y', 'Z')

$ python d2.py -a X X
usage: d2.py [-h] [-a {A,B,C} {X,Y,Z}]
d2.py: error: argument -a: invalid choice: 'X' (choose from 'A', 'B', 'C')

$ python d2.py -a a b
usage: d2.py [-h] [-a {A,B,C} {X,Y,Z}]
d2.py: error: argument -a: invalid choice: 'a' (choose from 'A', 'B', 'C')

如上所示，您只需使用 MultichoiceArgumentParser，将 MultichoiceFormatter 作为 formatter_class 参数。要使用多个不同的选择参数进行论证，choice 必须是序列的序列，与 nargs 的长度相同，并且 action 必须是 MultichoiceAction。这与 store 的行为方式相同，因此其他行为将需要更多的子类化。

Python argparse 第二选择

Python argparse second choices

python

argparse

python-3.x