使用argparse模块可以避免自己编写必需参数检查的繁琐操作。下面的示例使用“子解析器”或“子命令”。我已经为“dump”和“format”实现了一个子解析器。
import argparse
parser = argparse.ArgumentParser()
parser.add_argument('file', help='The file you want to act on.')
subparsers = parser.add_subparsers(dest='subcommand')
subparsers.required = True # required since 3.7
# subparser for dump
parser_dump = subparsers.add_parser('dump')
# add a required argument
parser_dump.add_argument(
'format',
choices=['csv', 'json'],
help='Dump the file in this format.')
# subparser for upload
parser_upload = subparsers.add_parser('upload')
# add a required argument
parser_upload.add_argument(
'server',
choices=['amazon', 'imgur'],
help='Upload the file to this service.')
args = parser.parse_args()
print args
if args.subcommand == 'dump':
print 'I will now dump "%s" in the %s format' % (args.file, args.format)
if args.subcommand == 'upload':
print 'I will now upload "%s" to %s' % (args.file, args.server)
这在命令行上看起来像这样:
$ python ap.py
usage: ap.py [-h] file {upload,dump} ...
ap.py: error: too few arguments
$ python ap.py tmp.txt
usage: ap.py [-h] file {upload,dump} ...
ap.py: error: too few arguments
上传：
$ python ap.py tmp.txt upload
usage: ap.py file upload [-h] {amazon,imgur}
ap.py file upload: error: too few arguments
$ python ap.py tmp.txt upload amazo
usage: ap.py file upload [-h] {amazon,imgur}
ap.py file upload: error: argument server: invalid choice: 'amazo' (choose from 'amazon', 'imgur')
$ python ap.py tmp.txt upload amazon
Namespace(file='tmp.txt', server='amazon', subcommand='upload')
I will now upload "tmp.txt" to amazon
$ python ap.py tmp.txt upload imgur
Namespace(file='tmp.txt', server='imgur', subcommand='upload')
I will now upload "tmp.txt" to imgur
转储：
$ python ap.py tmp.txt dump
usage: ap.py file dump [-h] {csv,json}
ap.py file dump: error: too few arguments
$ python ap.py tmp.txt dump csv
Namespace(file='tmp.txt', format='csv', subcommand='dump')
I will now dump "tmp.txt" in the csv format
$ python ap.py tmp.txt dump json
Namespace(file='tmp.txt', format='json', subcommand='dump')
I will now dump "tmp.txt" in the json format
print不是需要()吗？为什么上面的例子中没有使用呢？当我运行上面的例子时会出错，因为print告诉我语法应该是print('something')而不是print 'something'。这是特定于环境的怪异行为吗？（我在Windows上运行） - undefinedprint在Python 2中是这样工作的，这个答案是2012年时Python 2还很常见的时候给出的。 - undefined另一种处理该问题的方式是使用子命令（如git）以"action"作为第一个参数：
script dump --dump-format="foo"
script upload
argparse 不允许多个 subparsers。 - Liangdump dumpsubcommand1，dump subcommand2，upload subcommand3 等等？ - Adrian Wparser.error：import argparse
parser = argparse.ArgumentParser()
parser.add_argument('--action', choices=['upload', 'dump'], default='dump')
parser.add_argument('--dump-format')
args = parser.parse_args()
if args.action != 'dump' and args.dump_format:
parser.error('--dump-format can only be set when --action=dump.')
这取决于您所谓的“自己处理所有逻辑”的定义。您仍然可以使用argparse，并通过最小的努力添加转储选项，而无需使用子命令：
from argparse import ArgumentParser
from sys import argv
parser = ArgumentParser()
action_choices = ['upload', 'dump']
parser.add_argument('--action', choices=action_choices, default=action_choices[1])
parser.add_argument('--dump-format', required=(action_choices[1] in argv))
试一试。
假设你有一个工具，可以列出、添加和删除以下结构的表中的记录：
| id | sitekey | response | status |
|---|---|---|---|
| 1 | 123456 | valid | a |
| 2 | 234567 | invalid | |
| 3 | 345678 | invalid | c |
| 4 | 456789 | valid | d |
而且你想要以下操作和参数：
那么，你可以使用类似下面的代码：
import argparse
import sys
operation_choices = ['list', 'add', 'remove']
parser = argparse.ArgumentParser()
parser.add_argument("--operation",
choices = operation_choices,
default = operation_choices[0],
help = "Your help!",
required = True)
# list operation subarguments
if True in list(map(lambda x: operation_choices[0] in x, sys.argv)):
parser.add_argument("--from",
type = int,
default = 1,
help = "Your help!",
required = False)
parser.add_argument("--to",
type = int,
help = "Your help!",
required = False)
parser.add_argument("--short-response",
type = bool,
default = True,
help = "Your help!",
required = False)
# add operation subarguments
if True in list(map(lambda x: operation_choices[1] in x, sys.argv)):
parser.add_argument("--sitekey",
type = str,
help = "Your help!",
required = True)
parser.add_argument("--response",
type = str,
help = "Your help!",
required = True)
parser.add_argument("--status",
type = str,
help = "Your help!",
required = False)
# remove operation subarguments
if True in list(map(lambda x: operation_choices[2] in x, sys.argv)):
parser.add_argument("--id",
type = int,
help = "Your help!",
required = True)
args = parser.parse_args()
# Your operations...
因此，当您运行：
$ python tool.py --operation=list
This run, no required arguments
$ python tool.py --operation=add
usage: tool.py [-h] --operation {list,add,remove} --sitekey SITEKEY --response RESPONSE [--status STATUS]
tool.py: error: the following arguments are required: --sitekey, --response
$ python tool.py --operation=remove
usage: tool.py [-h] --operation {list,add,remove} --id ID
tool.py: error: the following arguments are required: --id
$ python tool.py --help
usage: tool.py [-h] --operation {list,add,remove}
options:
-h, --help show this help message and exit
--operation {list,add,remove}
Your help!
$ python tool.py --operation=list --help
usage: tool.py [-h] --operation {list,add,remove} [--from FROM] [--to TO] [--short-response SHORT_RESPONSE]
options:
-h, --help show this help message and exit
--operation {list,add,remove}
Your help!
--from FROM Your help!
--to TO Your help!
--short-response SHORT_RESPONSE
Your help!
$ python tool.py --operation=add --help
usage: tool.py [-h] --operation {list,add,remove} --sitekey SITEKEY --response RESPONSE [--status STATUS]
options:
-h, --help show this help message and exit
--operation {list,add,remove}
Your help!
--sitekey SITEKEY Your help!
--response RESPONSE Your help!
--status STATUS Your help!
$ python tool.py --operation=remove --help
usage: tool.py [-h] --operation {list,add,remove} --id ID
options:
-h, --help show this help message and exit
--operation {list,add,remove}
Your help!
--id ID Your help!
--action=dump-csv或--action=dump-some-other-format这样做是否是可行的选择？这将完全缓解“必需选项”的问题。 - dcrosta