Tadek Kijkowski <tkijkow...@gmail.com> added the comment:
This is, I think, smallest functional example for matching optional parameters
with positionals - fruits.py:
import argparse
DEFAULT_COLOR="plain"
class AddFruitAction(argparse.Action):
def __call__(self, parser, namespace, values, option_string=None):
for fruit in values:
namespace.fruits.append({'name': fruit, 'color': namespace.color})
namespace.color = DEFAULT_COLOR
def show_fruits(fruits):
for fruit in fruits:
print(f"{fruit['color']} {fruit['name']}")
parser = argparse.ArgumentParser(greedy=True)
parser.add_argument('--color', default=DEFAULT_COLOR)
parser.add_argument('fruits', nargs='*', action=AddFruitAction, default=[])
args = parser.parse_args()
show_fruits(args.fruits)
It starts with 'namespace.color' set to 'DEFAULT_COLOR' -
'default=DEFAULT_COLOR' takes care of that, and with 'namespace.fruits' set to
empty list - via 'default=[]'.
For each group of positional command-line arguments, AddFruitAction is called
with one or more fruit names in 'value'. The method iterates over them adding
series of dicts to the 'fruits' list. The 'namespace.color' is immediately
reset to default value, because we want the 'color' to apply to one following
'fruit'. If we wanted the 'color' to apply to all following 'fruits' the action
class could just leave it alone.
After parsing is done, we get our namespace assigned to args, with list of
color + fruit name pairs in 'args.fruits'.
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Python tracker <rep...@bugs.python.org>
<https://bugs.python.org/issue42973>
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