我在Python 2.7中使用argparse来解析输入选项。我的选项之一是多项选择。我想在它的帮助文本中做一个列表。
from argparse import ArgumentParser
parser = ArgumentParser(description='test')
parser.add_argument('-g', choices=['a', 'b', 'g', 'd', 'e'], default='a',
help="Some option, where\n"
" a = alpha\n"
" b = beta\n"
" g = gamma\n"
" d = delta\n"
" e = epsilon")
parser.parse_args()
然而,argparse会删除所有换行和连续的空格。结果如下所示
~/Downloads:52$ python2.7 x.py -h
usage: x.py [-h] [-g {a,b,g,d,e}]
test
optional arguments:
-h, --help show this help message and exit
-g {a,b,g,d,e} Some option, where a = alpha b = beta g = gamma d = delta e
= epsilon
如何在帮助文本中插入换行?
使用RawTextHelpFormatter获取新行并处理缩进的另一种简单方法是
import argparse
parser = argparse.ArgumentParser(
description='test', formatter_class=argparse.RawTextHelpFormatter)
parser.add_argument('-g', choices=['a', 'b', 'g', 'd', 'e'], default='a',
help=('Some option, where\n'
' a = alpha\n'
' b = beta\n'
' g = gamma\n'
' d = delta\n'
' e = epsilon'))
parser.parse_args()
输出为
$ python2 x.py -h
usage: x.py [-h] [-g {a,b,g,d,e}]
test
optional arguments:
-h, --help show this help message and exit
-g {a,b,g,d,e} Some option, where
a = alpha
b = beta
g = gamma
d = delta
e = epsilon
如果你只是想覆盖一个选项,你不应该使用RawTextHelpFormatter。相反,子类化HelpFormatter并为应该处理“原始”的选项提供一个特殊的介绍(我使用“R|rest of help”):
import argparse
class SmartFormatter(argparse.HelpFormatter):
def _split_lines(self, text, width):
if text.startswith('R|'):
return text[2:].splitlines()
# this is the RawTextHelpFormatter._split_lines
return argparse.HelpFormatter._split_lines(self, text, width)
并使用它:
from argparse import ArgumentParser
parser = ArgumentParser(description='test', formatter_class=SmartFormatter)
parser.add_argument('-g', choices=['a', 'b', 'g', 'd', 'e'], default='a',
help="R|Some option, where\n"
" a = alpha\n"
" b = beta\n"
" g = gamma\n"
" d = delta\n"
" e = epsilon")
parser.parse_args()
对.add_argument()的任何其他调用,其中帮助不是以R|开始的,将被正常包装。
这是我对argparse改进的一部分。完整的SmartFormatter也支持添加
所有选项的默认值,以及实用程序描述的原始输入。完整版
有它自己的_split_lines方法,这样对版本字符串所做的任何格式化都会被保留:
parser.add_argument('--version', '-v', action="version",
version="version...\n 42!")
我来这里寻找方法来获得ArgumentDefaultsHelpFormatter的行为,但与换行符和制表符荣誉。特洛伊的代码让我接近了,但最终的结果更简单一些:
class CustomArgumentFormatter(argparse.ArgumentDefaultsHelpFormatter):
"""
Formats help text to honor newlines and tabs (and show default values).
"""
# Match multiples of regular spaces only.
_SPACE_MATCHER = re.compile(r' +', re.ASCII)
def _split_lines(self, text, width):
new_text = []
for line in text.splitlines():
# For each newline in the help message, replace any multiples of
# whitespaces (due to indentation in source code) with one space.
line = self._SPACE_MATCHER.sub(' ', line).rstrip()
# Fit the line length to the console width
new_text.extend(textwrap.wrap(line, width))
return new_text
然后换行符和制表符将按预期出现:
parser = argparse.ArgumentParser(formatter_class=CustomArgumentFormatter)
parser.add_argument(
'--ethernet_config', type=str, required=False, default=None,
help='Path to a text file that specifies Ethernet network IP settings \
to use on the board. For example: \
\n\t ip=192.0.2.100 \
\n\t subnet_mask=255.255.255.0 \
\n\t gateway=192.0.2.1')
如果存在默认值,以下python 3格式化器将追加默认值并保留行长。
from argparse import ArgumentParser, ArgumentDefaultsHelpFormatter, \
RawTextHelpFormatter
import textwrap
class CustomArgumentFormatter(ArgumentDefaultsHelpFormatter, RawTextHelpFormatter):
"""Formats argument help which maintains line length restrictions as well as appends default value if present."""
def _split_lines(self, text, width):
text = super()._split_lines(text, width)
new_text = []
# loop through all the lines to create the correct wrapping for each line segment.
for line in text:
if not line:
# this would be a new line.
new_text.append(line)
continue
# wrap the line's help segment which preserves new lines but ensures line lengths are
# honored
new_text.extend(textwrap.wrap(line, width))
return new_text
然后用你的新格式化器创建你的参数解析器:
my_arg_parser = ArgumentParser(formatter_class=CustomArgumentFormatter)
# ... add your arguments ...
print(my_arg_parser.format_help())