Bash issue when using argparse and nargs='?' #181
Description
error received:
bash: ((: 6 + 1 - 7 - 0 >= ? : syntax error: operand expected (error token is "? ")
output snippet of shtab completion:
_shtab_example___add_template_nargs=?
_shtab_example__a_nargs=?
program:
example.py
command ran:
example.py --ext html --ext pdf myfile.txt --add-template <TAB>
Other examples:
$ example.py --ext html --ext pdf file1.txt
outfile='file1.html' template=None
outfile='file1.pdf' template=None
$ example.py --ext html --ext pdf file1.txt --add-template
outfile='file1.html' template=html
outfile='file1.pdf' template=pdf
$ example.py --ext html --ext pdf file1.txt --add-template to_
outfile='file1.html' template=to_html
outfile='file1.pdf' template=to_pdf
shtab command:
shtab \
--error-unimportable \
--verbose \
--shell=bash \
--prog example.py \
example.parse_arguments \
| tee "./completions/example.py"shtab 1.7.1
Python 3.12.6
GNU bash, version 5.2.21(1)-release (x86_64-pc-linux-gnu)
I run
export PATH=$PWD:$PATH
source completions/example.pyThen I run the command above and receive the error.
contents of example.py:
#!/usr/bin/env python3
"""Example to test shtab issue."""
import argparse
import pathlib
def parse_arguments():
parser = argparse.ArgumentParser(description=__doc__)
parser.add_argument(
'--add-template', '-a',
nargs='?',
default=None,
const='',
type=str,
help=('Optional. If set add a template. Type string for a prefix.'),
)
parser.add_argument(
'--ext', '-e',
dest='exts',
metavar='file_extension',
action='extend',
required=True,
nargs=1,
type=str,
help=(''),
)
parser.add_argument(
'file',
type=pathlib.Path,
help='Name of a file',
)
return parser
if __name__ == '__main__':
parser = parse_arguments()
args, unknown_args = parser.parse_known_args()
for ext in args.exts:
outfile = args.file.with_suffix(f".{ext}").name
if args.add_template is not None:
print(f"{outfile=} template={args.add_template + ext}")
else:
print(f"{outfile=} template=None")