使参数解析器接受绝对数字和百分比的最佳方法? [英] Best way to make argument parser accept absolute number and percentage?

问题描述

我正在尝试编写要与Nagios一起使用的Nagios样式检查.我有一个工作脚本，它接受类似-w 15 -c 10的内容，并将其解释为警告为15％，严重为10％".但是我才意识到，在内置的Nagios插件中，相同的参数表示警告为15MB，严重为10MB".相反，我需要输入-w 15% -c 10%以获得上述行为.

I am trying to write a Nagios style check to use with Nagios. I have working script that takes in something like -w 15 -c 10 and interprets that as "Warning at 15%, Critical at 10%". But I just realized that in the built-in Nagios plugins, the same arguments would mean "Warning at 15MB, Critical at 10MB"; I would instead need to enter -w 15% -c 10% to get the above behavior.

所以我的问题是，使我的脚本像内置Nagios脚本一样运作的最佳方法是什么?我能想到的唯一方法是接受参数作为字符串并将其解析，但是有没有更整洁的方法?

So my question is, what is the best way to make my script behave like the built-in Nagios scripts? The only way I can think of is accepting the argument as a string and parsing it, but is there a neater way?

推荐答案

您可以使用自己的类作为参数的类型:

You can use your own class as type for the arguments:

import argparse

class Percent(object):
    def __new__(self,  percent_string):
        if not percent_string.endswith('%'):
            raise ValueError('Need percent got {}'.format(percent_string))
        value = float(percent_string[:-1]) * 0.01
        return value

parser = argparse.ArgumentParser(description="with percent")
parser.add_argument('-w', '--warning', type=Percent)
parser.add_argument('-c', '--critcal', type=Percent)

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

输出:

python parse_percent.py  -w 15%
0.15

python parse_percent.py  -w 15
usage: parse-percent.py [-h] [-w WARNING] [-c CRITCAL]
parse-percent.py: error: argument -w/--warning: invalid Percent value: '15'

适用于百分比或MB的版本

class Percent(object):
    def __new__(self,  percent_string):
        if percent_string.endswith('%'):
            return float(percent_string[:-1]), 'percent'
        else:
            return float(percent_string), 'MB'

parser = argparse.ArgumentParser(description="with percent")
parser.add_argument('-w', '--warning', type=Percent)
parser.add_argument('-c', '--critcal', type=Percent)

args = parser.parse_args()
value, unit = args.warning
print('{} {}'.format(value, unit))

输出:

python parse_percent.py -w 15
15.0 MB
python parse_percent.py -w 15%
15.0 percent

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