Python 允许 Argparse 参数的特定值

Allowing specific values for an Argparse argument

提问by Moshe

Is it possible to require that an argparseargument be one of a few preset values?

是否可以要求argparse参数是几个预设值之一？

My current approach would be to examine the argument manually and if it's not one of the allowed values call print_help()and exit.

我目前的方法是手动检查参数，如果它不是允许的值之一，则调用print_help()和退出。

Here's the current implementation:

这是当前的实现：

...
parser.add_argument('--val',
                    help='Special testing value')

args = parser.parse_args(sys.argv[1:])
if args.val not in ['a', 'b', 'c']:
    parser.print_help()
    sys.exit(1)

It's not that this is particularly difficult, but rather that it appears to be messy.

这并不是特别困难，而是它看起来很混乱。

采纳答案by Moshe

An argparse argument can be limited to specific values with the choicesparameter:

argparse 参数可以限制为具有choices参数的特定值：

...
parser.add_argument('--val',
                    choices=['a', 'b', 'c'],
                    help='Special testing value')

args = parser.parse_args(sys.argv[1:])

See the docsfor more details.

有关更多详细信息，请参阅文档。