如何为 argparse 设计面向对象的子解析器？

Problem

我正在构建一个包含很多子命令的包管理器。我希望有一个类似于以下的类结构。

class ListCommand:
  def __init__(self):
    name = "list"
    alias = "ls"
    short_description = "A useful simple line that explains the command"

  def help(self):
    # Display help

  def command(self):
    # do stuff when command is called

我如何编写子解析器来处理这样的事情？我找到了一个example http://chase-seibert.github.io/blog/2014/03/21/python-multilevel-argparse.htmlonline 可以在没有子解析器的情况下执行类似的操作。

cmd 类和解析器：

import argparse

class Cmd:
  def __init__(self,name):
    self.name = name

  def __call__(self, args):
    # do stuff when command is called
    print('Executing %s'%self)
    print('args %s'% args)

  def make_sup(self,sp):
      self.parser = sp.add_parser(self.name)
      self.parser.add_argument('--foo')
      self.parser.set_defaults(action=self)

  def __repr__(self):
      return '<Cmd> %s'%self.name

cmds = []
cmds.append(Cmd('list'))
cmds.append(Cmd('foo'))
cmds.append(Cmd('bar'))
print(cmds)

parser = argparse.ArgumentParser()
sp = parser.add_subparsers(dest='cmd')
for cmd in cmds:
    cmd.make_sup(sp)
print(parser._defaults)

args = parser.parse_args()
print(args)
args.action(args)

样本运行：

1834:~/mypy$ python stack46595691.py list --foo xxxx
[<Cmd> list, <Cmd> foo, <Cmd> bar]
{}
Namespace(action=<Cmd> list, cmd='list', foo='xxxx')
Executing <Cmd> list
args Namespace(action=<Cmd> list, cmd='list', foo='xxxx')
1837:~/mypy$ python stack46595691.py bar
[<Cmd> list, <Cmd> foo, <Cmd> bar]
{}
Namespace(action=<Cmd> bar, cmd='bar', foo=None)
Executing <Cmd> bar
args Namespace(action=<Cmd> bar, cmd='bar', foo=None)
1838:~/mypy$ python stack46595691.py foo -h
[<Cmd> list, <Cmd> foo, <Cmd> bar]
{}
usage: stack46595691.py foo [-h] [--foo FOO]

optional arguments:
  -h, --help  show this help message and exit
  --foo FOO

您可能还想看看plac，一个子类化的包ArgumentParser, https://pypi.python.org/pypi/plac https://pypi.python.org/pypi/plac

它可以根据函数的参数构造子解析器。