python - docopt + 模式验证

Question

有没有更好的方法来处理这个验证：

#!/usr/bin/env python
""" command.

Usage:
  command start ID
  command finish ID FILE
  command (-h | --help)
  command (-v | --version)

Arguments:
  FILE     input file
  PATH     out directory

Options:
  -h --help     Show this screen.
  -v --version  Show version.
"""

from docopt import docopt
from schema import Schema, Use, SchemaError

if __name__ == '__main__':
    args = docopt(__doc__, version='command alpha')

    # Remove False or None keys from args dict
    for k, v in args.items():
        if (not v):
            args.pop(k)

    if 'start' in args:
        args.pop('start')
        schema = Schema({
            'FILE': Use(open, error='FILE should be readable'),
            'ID': Use(int, error='ID should be an int'),
        })
    elif 'finish' in args:
        args.pop('finish')
        schema = Schema({
            'FILE': Use(open, error='FILE should be readable'),
            'ID': Use(int, error='ID should be an int'),
        })

    try:
        args = schema.validate(args)
    except SchemaError as e:
        exit(e)

    print(args)

Answer 1

我会做以下事情：

#!/usr/bin/env python
"""Command.

Usage:
  command start ID
  command finish ID FILE
  command (-h | --help)
  command (-v | --version)

Arguments:
  ID
  FILE     input file

Options:
  -h --help     Show this screen.
  -v --version  Show version.

"""
from docopt import docopt
from schema import Schema, Use, Or, SchemaError

if __name__ == '__main__':
    args = docopt(__doc__, version='command alpha')

    id_schema = Use(int, error='ID should be an int')
    file_schema = Or(None, Use(open, error='FILE should be readable'))
    try:
        args['ID'] = id_schema.validate(args['ID'])
        args['FILE'] = file_schema.validate(args['FILE'])
    except SchemaError as e:
        exit(e)

    print(args)

尽管我希望模式可以使用单个模式而不是两个模式来表达相同的含义。我将尝试使将来能够制作如下模式：

schema = Schema({'ID': Use(int, error='ID should be an int'),
                 'FILE': Or(None, Use(open, error='FILE should be readable')),
                 object: object})

这意味着我只object: object关心'ID'并且'FILE'所有其他键/值都可以是任意对象。

更新

从 0.2.0 版开始，schema现在可以正确处理这种情况：

schema = Schema({'ID': Use(int, error='ID should be an int'),
                 'FILE': Or(None, Use(open, error='FILE should be readable')),
                 object: object})