实现"[command] [action] [parameter]"样式命令行界面？

实现命令行UI的"最干净"方式是什么,类似于git,例如:

git push origin/master
git remote add origin git://example.com master

理想情况下还允许更灵活的解析,例如,

jump_to_folder app theappname v2
jump_to_folder app theappname source
jump_to_folder app theappname source v2
jump_to_folder app theappname build v1
jump_to_folder app theappname build 1
jump_to_folder app theappname v2 build

jump_to_folder是脚本名称,app是命令,theappname是"固定位置"参数,"构建"和"v2"等是参数(例如,可能的参数是任何数字/任何前缀为av的数字,或者build/source/TMP /配置)

我可以用一系列if/ else/ 手动解析参数elifs,但必须有更优雅的方法来做到这一点？

作为一个完全理论上的例子,我可以描述UI模式..

app:
    fixed: application_name

    optional params:
        arg subsection:
            "build"
            "source"
            "tmp"
            "config"

        arg version:
            integer
            "v" + integer

然后通过上面的模式解析提供的参数,并获取一个字典:

>>> print schema.parse(["app", "theappname", "v1", "source"])
{
    "application_name": "theappname",
    "params":{
        "subsection": "source",
        "version":"v1"
    }
}

这样的系统存在吗？如果没有,我将如何沿着这些方向实施某些内容？

argparse是完美的,特别是"子命令"和位置args

import argparse


def main():
    arger = argparse.ArgumentParser()

    # Arguments for top-level, e.g "subcmds.py -v"
    arger.add_argument("-v", "--verbose", action="count", default=0)

    subparsers = arger.add_subparsers(dest="command")

    # Make parser for "subcmds.py info ..."
    info_parser = subparsers.add_parser("info")
    info_parser.add_argument("-m", "--moo", dest="moo")

    # Make parser for "subcmds.py create ..."
    create_parser = subparsers.add_parser("create")
    create_parser.add_argument("name")
    create_parser.add_argument("additional", nargs="*")

    # Parse
    opts = arger.parse_args()

    # Print option object for debug
    print opts

    if opts.command == "info":
        print "Info command"
        print "--moo was %s" % opts.moo

    elif opts.command == "create":
        print "Creating %s" % opts.name
        print "Additional: %s" % opts.additional

    else:
        # argparse will error on unexpected commands, but
        # in case we mistype one of the elif statements...
        raise ValueError("Unhandled command %s" % opts.command)


if __name__ == '__main__':
    main()

这可以这样使用:

$ python subcmds.py create myapp v1 blah
Namespace(additional=['v1', 'blah'], command='create', name='myapp', verbose=0)
Creating myapp
Additional: ['v1', 'blah']
$ python subcmds.py info --moo
usage: subcmds.py info [-h] [-m MOO]
subcmds.py info: error: argument -m/--moo: expected one argument
$ python subcmds.py info --moo 1
Namespace(command='info', moo='1', verbose=0)
Info command
--moo was 1

该cmd模块可能适用于此.

例:

import cmd

class Calc(cmd.Cmd):
    def do_add(self, arg):
        print sum(map(int, arg.split()))

if __name__ == '__main__':
    Calc().cmdloop()

运行:

$python calc.py
(Cmd) add 4 5
9
(Cmd) help

Undocumented commands:
======================
add  help

(Cmd)

有关详细信息,请参阅Python文档或PyMOTW站点.