New submission from Ying Zhang <[email protected]>:
Code is attached. Comments in line.
from argparse import ArgumentParser, ArgumentDefaultsHelpFormatter
parser1 = ArgumentParser(formatter_class=ArgumentDefaultsHelpFormatter)
parser1.add_argument('--foo',
default='default_value_for_foo', required=False)
# this will not print the default value for foo. I think this is not the most
natural choice, given that the user has asked for
ArgumentDefaultsHelpFormatter, but acceptable since the user didn't define help
here.
parser1.add_argument('--bar', help='',
default='default_value_for_bar', required=False)
# this will not print the default value for bar. Again, acceptable but I feel
not the most natural.
parser1.add_argument('--baz', help=' ',
default='default_value_for_baz', required=False)
# this will print the default value for baz.
parser1.print_help()
parser2 = ArgumentParser()
parser2.add_argument('--baz', help=' ',
default='default_value_for_baz', required=False)
# this will break, which surprises me.
parser2.print_help()
----------------
Result:
python argparse_help_demo.py
usage: argparse_help_demo.py [-h] [--foo FOO] [--bar BAR] [--baz BAZ]
optional arguments:
-h, --help show this help message and exit
--foo FOO
--bar BAR
--baz BAZ (default: default_value_for_baz)
Traceback (most recent call last):
File "argparse_help_demo.py", line 21, in <module>
parser2.print_help()
File
"/nfs/statbuild/zhangyi/conda_envs/net37_env0/lib/python3.7/argparse.py", line
2474, in print_help
self._print_message(self.format_help(), file)
File
"/nfs/statbuild/zhangyi/conda_envs/net37_env0/lib/python3.7/argparse.py", line
2458, in format_help
return formatter.format_help()
File
"/nfs/statbuild/zhangyi/conda_envs/net37_env0/lib/python3.7/argparse.py", line
284, in format_help
help = self._root_section.format_help()
File
"/nfs/statbuild/zhangyi/conda_envs/net37_env0/lib/python3.7/argparse.py", line
215, in format_help
item_help = join([func(*args) for func, args in self.items])
File
"/nfs/statbuild/zhangyi/conda_envs/net37_env0/lib/python3.7/argparse.py", line
215, in <listcomp>
item_help = join([func(*args) for func, args in self.items])
File
"/nfs/statbuild/zhangyi/conda_envs/net37_env0/lib/python3.7/argparse.py", line
215, in format_help
item_help = join([func(*args) for func, args in self.items])
File
"/nfs/statbuild/zhangyi/conda_envs/net37_env0/lib/python3.7/argparse.py", line
215, in <listcomp>
item_help = join([func(*args) for func, args in self.items])
File
"/nfs/statbuild/zhangyi/conda_envs/net37_env0/lib/python3.7/argparse.py", line
527, in _format_action
parts.append('%*s%s\n' % (indent_first, '', help_lines[0]))
IndexError: list index out of range
----------
components: Library (Lib)
messages: 364091
nosy: Ying Zhang
priority: normal
severity: normal
status: open
title: argparse print_help breaks when help is blank space
type: crash
versions: Python 3.7
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Python tracker <[email protected]>
<https://bugs.python.org/issue39955>
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