python::argparse:如何逐级打印帮助?
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【中文标题】python::argparse:如何逐级打印帮助?【英文标题】:python::argparse: How to print help level-by-level? 【发布时间】:2022-01-04 21:05:51 【问题描述】:我有一个像 'git' 这样的多级命令行程序。
my_cli service action --options
我想逐级显示帮助消息,并且我不希望用户显式键入“-h”或“--help”。
例如,
$ my_cli <== display help of all services
$ my_cli service1 <== display help for service1 only
$ my_cli service1 action1 <== display help for service1/action1 only
代码如下所示。
import argparse
argument_parser = argparse.ArgumentParser(description="my_cli")
root_parsers = argument_parser.add_subparsers(title="service", dest="service")
service1_parsers = root_parsers.add_parser("service1", help="service1").add_subparsers(title="action", dest="action")
service2_parsers = root_parsers.add_parser("service2", help="service2").add_subparsers(title="action", dest="action")
service1_action1_parser = service1_parsers.add_parser("action1", help="action1")
service1_action1_parser.add_argument("-a", "--address", required=True, help="address or hostname of the server")
...
args = argument_parser.parse_args()
if (args.service is None):
argument_parser.print_help()
exit(1)
elif (args.action is None):
if (args.service == "service1"):
service1_parsers.print_help() <== This doesn't work.
exit(1)
...
else:
if (args.service == "service1") AND (args.action == "action1"):
service1_action1_parser.print_help() <== This doesn't work.
exit(1)
...
【问题讨论】:
【参考方案1】:在您的示例中,调用 my_cli service1 action1
确实 会显示某种帮助消息,但它更多的是使用消息,因为您已将 --address
参数标记为必需,这导致解析器失败验证。使用信息是
usage: test3.py service1 action1 [-h] -a ADDRESS
test3.py service1 action1: error: the following arguments are required: -a/--address
在您调用my_cli service1
的示例中没有显示帮助消息的问题是,您在子解析器上调用print_help()
,而您应该在解析器上调用它。这样的事情应该可以工作。
import argparse
argument_parser = argparse.ArgumentParser(description="my_cli")
root_parsers = argument_parser.add_subparsers(title="service", dest="service")
service1_parser = root_parsers.add_parser("service1", help="service1")
service1_subparsers = service1_parser.add_subparsers(title="action", dest="action")
service2_parser = root_parsers.add_parser("service2", help="service2")
service2_subparsers = service2_parser.add_subparsers(title="action", dest="action")
service1_action1_parser = service1_subparsers.add_parser("action1", help="action1")
# I removed the required=True here for the purposes of showing how to get the help message
service1_action1_parser.add_argument("-a", "--address", help="address or hostname of the server")
args = argument_parser.parse_args()
if args.service is None:
argument_parser.print_help()
exit(1)
elif args.action is None:
if args.service == "service1":
# call print_help() on a parser instead of a subparser
service1_parser.print_help()
elif args.service == "service2":
service2_parser.print_help()
exit(1)
elif args.service == "service1" and args.action == "action1":
service1_action1_parser.print_help()
exit(1)
我得到的输出是:
$ ./my_cli
usage: my_cli [-h] service1,service2 ...
my_cli
optional arguments:
-h, --help show this help message and exit
service:
service1,service2
service1 service1
service2 service2
$ ./my_cli service1
usage: my_cli service1 [-h] action1 ...
optional arguments:
-h, --help show this help message and exit
action:
action1
action1 action1
$ ./my_cli service1 action1
usage: my_cli service1 action1 [-h] [-a ADDRESS]
optional arguments:
-h, --help show this help message and exit
-a ADDRESS, --address ADDRESS
address or hostname of the server
【讨论】:
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