metavar和action在Python的argparse中意味着什么？ [英] What does metavar and action mean in argparse in Python?

问题描述

我正在阅读 argparse 模块。我对metavar和操作的含义感到困惑

I am reading through argparse module. I got stuck as what to metavar and action means

>>> parser.add_argument('integers', metavar='N', type=int, nargs='+',
...                     help='an integer for the accumulator')
>>> parser.add_argument('--sum', dest='accumulate', action='store_const',
...                     const=sum, default=max,
...                     help='sum the integers (default: find the max)')

我可能已经错过了，但是从我的阅读中我可以找不到元变量和
action（action = store_const等）的定义。

I might have missed but from what I read, I could not find definitions for metavar and action (action="store_const", etc). what do they actually mean?

推荐答案

metavar 用于帮助消息中预期参数的位置。请参阅 FOO 是默认的 metavar 此处：

metavar is used in help messages in a place of an expected argument. See FOO is a default metavar here:

>>> parser = argparse.ArgumentParser()
>>> parser.add_argument('--foo')
>>> parser.add_argument('bar')
>>> parser.parse_args('X --foo Y'.split())
Namespace(bar='X', foo='Y')
>>> parser.print_help()
usage:  [-h] [--foo FOO] bar
...

操作定义了如何处理命令-行参数：将其存储为常量，追加到列表中，存储布尔值等。有几种内置操作，加上编写自定义操作很容易。

action defines how to handle command-line arguments: store it as a constant, append into a list, store a boolean value etc. There are several built-in actions available, plus it's easy to write a custom one.

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