On 27/01/2023 21:31, Ivan "Rambius" Ivanov wrote:
Hello,
I am developing a script that accepts a time zone as an option. The
time zone can be any from pytz.all_timezones. I have
def main():
parser = argparse.ArgumentParser()
parser.add_argument("-z", "--zone", choices=pytz.all_timezones)
args = parser.parse_args()
print(args)
print(f"Specified timezone: {args.zone}")
It works, but when I run it with the -h option it dumps all entries in
pytz.all_timezones. I would like to modify the help format for just
-z|--zone option. I read the docs about HelpFormatter and argparse.py
and I ended up with
class CustomHelpFormatter(argparse.HelpFormatter):
def _metavar_formatter(self, action, default_metavar):
if action.dest == 'zone':
result = 'zone from pytz.all_timezones'
def format(tuple_size):
if isinstance(result, tuple):
return result
else:
return (result, ) * tuple_size
return format
else:
return super(CustomHelpFormatter,
self)._metavar_formatter(action, default_metavar)
def main():
parser = argparse.ArgumentParser(formatter_class=CustomHelpFormatter)
parser.add_argument("-z", "--zone", choices=pytz.all_timezones)
args = parser.parse_args()
print(args)
print(f"Specified timezone: {args.zone}")
This works, but is there a more elegant way to achieve it?
It may be sufficient to specify a metavar:
>>> import argparse
>>> p = argparse.ArgumentParser()
>>> p.add_argument("--foo", choices="alpha beta gamma".split(),
metavar="<any greek letter>")
[...]
>>> p.parse_args(["-h"])
usage: [-h] [--foo <any greek letter>]
optional arguments:
-h, --help show this help message and exit
--foo <any greek letter>
While that helps with --help it doesn't always prevent the choices list
from being spelt out:
>>> p.parse_args(["--foo", "whatever"])
usage: [-h] [--foo <any greek letter>]
: error: argument --foo: invalid choice: 'whatever' (choose from
'alpha', 'beta', 'gamma')
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