我有一个带有多个参数的程序，例如
breakfast.py --customer=vikings eggs sausage bacon
其中＆＃34;鸡蛋＆＃34;，＆＃34;香肠＆＃34;和＆＃34;培根＆＃34;可以从特定选择列表中指定。
现在我喜欢breakfast.py --help的输出看起来像这样：
usage: breakfast.py [-h] [--customer CUSTOMER] INGREDIENT [INGREDIENT ...]
positional arguments:
your choice of ingredients:
bacon Lovely bacon
egg The runny kind
sausage Just a roll
spam Glorious SPAM
tomato Sliced and diced
optional arguments:
-h, --help show this help message and exit
--customer CUSTOMER salutation for addressing the customer
我尝试了两种方法，但到目前为止我都失败了。
使用参数选择：
import argparse
parser = argparse.ArgumentParser()
toppings = {
'bacon': "Lovely bacon",
'egg': 'The runny kind',
'sausage': 'Just a roll',
'spam': 'Glorious SPAM',
'tomato': 'Sliced and diced',
}
parser.add_argument('--customer', default='Mr. and Mrs. Bun', action='store',
help='salutation for addressing the customer')
parser.add_argument('ingredients', nargs='+', choices=toppings.keys(),
help='your choice of ingredients')
options = parser.parse_args('--customer=Vikings egg sausage bacon'.split())
print("Dear {}, we are happy to serve you {}" \
.format(options.customer, ', '.join(options.ingredients)))
上述程序的使用打印出没有详细信息的dict格式列表：
usage: breakfast.py [-h] [--customer CUSTOMER]
{bacon,egg,sausage,spam,tomato}
[{bacon,egg,sausage,spam,tomato} ...]
positional arguments:
{bacon,egg,sausage,spam,tomato}
your choice of ingredients
将metavar='INGREDIENT'添加到add_argument('ingredients', ...)并未列出所有选项：
usage: breakfast.py [-h] [--customer CUSTOMER] INGREDIENT [INGREDIENT ...]
positional arguments:
INGREDIENT your choice of ingredients
我简单地尝试使用子程序：
import argparse
parser = argparse.ArgumentParser()
parser.add_argument('--customer', default='Mr. and Mrs. Bun', action='store',
help='salutation for addressing the customer')
ingredients = parser.add_subparsers(title='your choice of an ingredient',
dest='ingredient', metavar='ingredient')
ingredients.add_parser('bacon', help="Lovely bacon")
ingredients.add_parser('egg', help="The runny kind")
ingredients.add_parser('sausage', help="Just a roll")
ingredients.add_parser('spam', help="Glorious SPAM")
ingredients.add_parser('tomato', help="Sliced and diced")
options = parser.parse_args('--customer=Vikings spam'.split())
print("Dear {}, we are happy to serve you {}" \
.format(options.customer, options.ingredient))
以我喜欢的方式列出用法：
usage: breakfast.py [-h] [--customer CUSTOMER] ingredient ...
optional arguments:
-h, --help show this help message and exit
--customer CUSTOMER salutation for addressing the customer
your choice of an ingredient:
ingredient
bacon Lovely bacon
egg The runny kind
sausage Just a roll
spam Glorious SPAM
tomato Sliced and diced
默认情况下，子程序仅允许选择一个选项。幸运的是this answer shows it is possible to allow multiple subcommands），但这只是为了让格式正确。我最近从argparse转到ConfigArgParse，这种方法在那里失败了。
我认为我最好还原为使用具有多个选项的单个参数，并使用customat格式化。
不幸的是，关于调整argparse格式的文档很少，所以我很感激如何解决这个问题。
答案 0 :(得分：3)
将add_argument更改为：
parser.add_argument('ingredients', nargs='+', choices=toppings.keys(),
metavar='INGREDIENT',
help='your choice of ingredients: %(choices)s')
产生
usage: stack49969605.py [-h] [--customer CUSTOMER] INGREDIENT [INGREDIENT ...]
positional arguments:
INGREDIENT your choice of ingredients: bacon, egg, sausage, spam,
tomato
更改格式化程序：
formatter_class=argparse.RawTextHelpFormatter
以及add_argument help参数：
help = """
your choice of ingredients:
bacon Lovely bacon
egg The runny kind
sausage Just a roll
spam Glorious SPAM
tomato Sliced and diced
"""
)
产生
usage: stack49969605.py [-h] [--customer CUSTOMER] INGREDIENT [INGREDIENT ...]
positional arguments:
INGREDIENT
your choice of ingredients:
bacon Lovely bacon
egg The runny kind
sausage Just a roll
spam Glorious SPAM
tomato Sliced and diced
或者您可以使用argparse.RawDescriptionHelpFormatter，并将格式化的表格放在description或epilog中。
另一种选择是创建一个模仿subparsers类方面的Action子类。但这需要更深入地了解如何在格式化中处理此Action类。
class _SubParsersAction(Action):
class _ChoicesPseudoAction(Action):
subparsers Action对象维护此_choices_actions类的PseudoAction列表，仅仅是为了欺骗帮助格式化程序显示子分析符，就好像它们是一组嵌套的{ {1}}。此列表不用于解析;仅用于帮助格式化。
答案 1 :(得分：2)
根据这里的反馈，我深入研究了argparse代码。使用子分析符的合理解决方案发布在https://stackoverflow.com/a/49977713/428542。
此外，我能够找到为每个选项添加伪操作的解决方案，以及修改格式化程序的解决方案。最后，我提出了一个混合解决方案，为每个选项添加伪动作，但是只有格式化程序才能使用它们，通过利用一些实现细节。
第一个解决方案定义了一个自定义操作，其目的是什么都不做，但仍打印一些使用信息。这个NoAction类给出了不同的选项。
import argparse
class NoAction(argparse.Action):
def __init__(self, **kwargs):
kwargs.setdefault('default', argparse.SUPPRESS)
kwargs.setdefault('nargs', 0)
super(NoAction, self).__init__(**kwargs)
def __call__(self, parser, namespace, values, option_string=None):
pass
parser = argparse.ArgumentParser()
parser.register('action', 'none', NoAction)
parser.add_argument('--customer', default='Mr. and Mrs. Bun', action='store',
help='salutation for addressing the customer')
parser.add_argument('ingredients', nargs='*', metavar='INGREDIENT',
choices=['bacon', 'egg', 'sausage', 'spam', 'tomato'],
help='List of ingredients')
group = parser.add_argument_group(title='your choice of ingredients')
group.add_argument('bacon', help="Lovely bacon", action='none')
group.add_argument('egg', help="The runny kind", action='none')
group.add_argument('sausage', help="Just a roll", action='none')
group.add_argument('spam', help="Glorious SPAM", action='none')
group.add_argument('tomato', help="Sliced and diced", action='none')
options = parser.parse_args('--customer=Vikings egg sausage bacon'.split())
print("Dear {}, we are happy to serve you {}" \
.format(options.customer, ', '.join(options.ingredients)))
options = parser.parse_args(['--help'])
输出：
Dear Vikings, we are happy to serve you egg, sausage, bacon
usage: customchoices.py [-h] [--customer CUSTOMER]
[INGREDIENT [INGREDIENT ...]]
positional arguments:
INGREDIENT List of ingredients
optional arguments:
-h, --help show this help message and exit
--customer CUSTOMER salutation for addressing the customer
your choice of ingredients:
bacon Lovely bacon
egg The runny kind
sausage Just a roll
spam Glorious SPAM
tomato Sliced and diced
一个小缺点是个别选择都被添加到成分（用于解析）以及解析器（用于格式化）。我们还可以定义一种方法，直接将选择添加到成分解析器中：
import argparse
class NoAction(argparse.Action):
def __init__(self, **kwargs):
kwargs.setdefault('default', argparse.SUPPRESS)
kwargs.setdefault('nargs', 0)
super(NoAction, self).__init__(**kwargs)
def __call__(self, parser, namespace, values, option_string=None):
pass
class ChoicesAction(argparse._StoreAction):
def add_choice(self, choice, help=''):
if self.choices is None:
self.choices = []
self.choices.append(choice)
self.container.add_argument(choice, help=help, action='none')
parser = argparse.ArgumentParser()
parser.register('action', 'none', NoAction)
parser.register('action', 'store_choice', ChoicesAction)
parser.add_argument('--customer', default='Mr. and Mrs. Bun', action='store',
help='salutation for addressing the customer')
group = parser.add_argument_group(title='your choice of ingredients')
ingredients = group.add_argument('ingredients', nargs='*', metavar='INGREDIENT',
action='store_choice')
ingredients.add_choice('bacon', help="Lovely bacon")
ingredients.add_choice('egg', help="The runny kind")
ingredients.add_choice('sausage', help="Just a roll")
ingredients.add_choice('spam', help="Glorious SPAM")
ingredients.add_choice('tomato', help="Sliced and diced")
上面可能是我最喜欢的方法，尽管有两个动作子类。它只使用公共方法。
另一种方法是修改Formatter。这是可能的，它会将action.choices从列表['option1', 'option2']修改为dict {'option1': 'help_for_option1', 'option2', 'help_for_option2'}，并且或多或少地重新实现HelpFormatter._format_action()为HelpFormatterWithChoices.format_choices()：
import argparse
class HelpFormatterWithChoices(argparse.HelpFormatter):
def add_argument(self, action):
if action.help is not argparse.SUPPRESS:
if isinstance(action.choices, dict):
for choice, choice_help in action.choices.items():
self._add_item(self.format_choices, [choice, choice_help])
else:
super(HelpFormatterWithChoices, self).add_argument(action)
def format_choices(self, choice, choice_help):
# determine the required width and the entry label
help_position = min(self._action_max_length + 2,
self._max_help_position)
help_width = max(self._width - help_position, 11)
action_width = help_position - self._current_indent - 2
choice_header = choice
# short choice name; start on the same line and pad two spaces
if len(choice_header) <= action_width:
tup = self._current_indent, '', action_width, choice_header
choice_header = '%*s%-*s ' % tup
indent_first = 0
# long choice name; start on the next line
else:
tup = self._current_indent, '', choice_header
choice_header = '%*s%s\n' % tup
indent_first = help_position
# collect the pieces of the choice help
parts = [choice_header]
# add lines of help text
help_lines = self._split_lines(choice_help, help_width)
parts.append('%*s%s\n' % (indent_first, '', help_lines[0]))
for line in help_lines[1:]:
parts.append('%*s%s\n' % (help_position, '', line))
# return a single string
return self._join_parts(parts)
parser = argparse.ArgumentParser(formatter_class=HelpFormatterWithChoices)
toppings = {
'bacon': "Lovely bacon",
'egg': 'The runny kind',
'sausage': 'Just a roll',
'spam': 'Glorious SPAM',
'tomato': 'Sliced and diced',
}
parser.add_argument('--customer', default='Mr. and Mrs. Bun', action='store',
help='salutation for addressing the customer')
group = parser.add_argument_group(title='your choice of ingredients')
ingredients = group.add_argument('ingredients', nargs='*', metavar='INGREDIENT',
choices=toppings)
options = parser.parse_args('--customer=Vikings egg sausage bacon'.split())
print("Dear {}, we are happy to serve you {}" \
.format(options.customer, ', '.join(options.ingredients)))
print()
options = parser.parse_args(['--help'])
输出：
Dear Vikings, we are happy to serve you egg, sausage, bacon
usage: helpformatter.py [-h] [--customer CUSTOMER]
[INGREDIENT [INGREDIENT ...]]
optional arguments:
-h, --help show this help message and exit
--customer CUSTOMER salutation for addressing the customer
your choice of ingredients:
bacon Lovely bacon
egg The runny kind
sausage Just a roll
spam Glorious SPAM
tomato Sliced and diced
应该注意的是，这是唯一一种不打印帮助热线的方法＆＃34; INGREDIENTS＆＃34;本身，但只有选择。
然而，我不喜欢这种方法：它重新实现了太多的代码，并依赖于argparse的过多内部实现细节。
还有一种可能的混合方法：argparser中的子分析器代码使用属性action._choices_actions。这通常在_SubParsersAction类中，用于解析和格式化。如果我们使用此属性，但仅用于格式化，该怎么办？
import argparse
class ChoicesAction(argparse._StoreAction):
def __init__(self, **kwargs):
super(ChoicesAction, self).__init__(**kwargs)
if self.choices is None:
self.choices = []
self._choices_actions = []
def add_choice(self, choice, help=''):
self.choices.append(choice)
# self.container.add_argument(choice, help=help, action='none')
choice_action = argparse.Action(option_strings=[], dest=choice, help=help)
self._choices_actions.append(choice_action)
def _get_subactions(self):
return self._choices_actions
parser = argparse.ArgumentParser()
parser.register('action', 'store_choice', ChoicesAction)
parser.add_argument('--customer', default='Mr. and Mrs. Bun', action='store',
help='salutation for addressing the customer')
group = parser.add_argument_group(title='your choice of ingredients')
ingredients = group.add_argument('ingredients', nargs='*', metavar='INGREDIENT',
action='store_choice')
ingredients.add_choice('bacon', help="Lovely bacon")
ingredients.add_choice('egg', help="The runny kind")
ingredients.add_choice('sausage', help="Just a roll")
ingredients.add_choice('spam', help="Glorious SPAM")
ingredients.add_choice('tomato', help="Sliced and diced")
options = parser.parse_args('--customer=Vikings egg sausage bacon'.split())
print("Dear {}, we are happy to serve you {}" \
.format(options.customer, ', '.join(options.ingredients)))
print()
options = parser.parse_args(['--help'])
输出：
Dear Vikings, we are happy to serve you egg, sausage, bacon
usage: helpformatter2.py [-h] [--customer CUSTOMER]
[INGREDIENT [INGREDIENT ...]]
optional arguments:
-h, --help show this help message and exit
--customer CUSTOMER salutation for addressing the customer
your choice of ingredients:
INGREDIENT
bacon Lovely bacon
egg The runny kind
sausage Just a roll
spam Glorious SPAM
tomato Sliced and diced
这也是一个不错的解决方案，尽管它依赖于_get_subactions()方法的实现细节。
答案 2 :(得分：0)
为什么不自己解析参数而不使用argparser？然后，您可以按照自己喜欢的方式自由格式化帮助屏幕。
import sys
if sys.argv[1] in ['-h','--help']:
print "usage: breakfast.py [-h] [--customer CUSTOMER] INGREDIENT [INGREDIENT ...]\n\npositional arguments:\n\tyour choice of ingredients:\n\t\tbacon Lovely bacon\n\t\tegg The runny kind\n\t\tsausage Just a roll\n\t\tspam Glorious SPAM\n\t\ttomato Sliced and diced\n\noptional arguments:\n\t-h, --help show this help message and exit\n\t--customer CUSTOMER salutation for addressing the customer"
customer_arg = sys.argv[1]
ingrediants = sys.argv[2:len(sys.argv)]
customer = customer_arg.split('=')[1]
这将打印：
usage: breakfast.py [-h] [--customer CUSTOMER] INGREDIENT [INGREDIENT ...]
positional arguments:
your choice of ingredients:
bacon Lovely bacon
egg The runny kind
sausage Just a roll
spam Glorious SPAM
tomato Sliced and diced
optional arguments:
-h, --help show this help message and exit
--customer CUSTOMER salutation for addressing the customer
然后，您可以使用ingrediant列表执行下一步操作。我希望这会有所帮助。