On 11/27/23 04:29, Dom Grigonis via Python-list wrote:
Hi all,
I have a situation, maybe someone can give some insight.
Say I want to have input which is comma separated array (e.g.
paths='path1,path2,path3') and convert it to the desired output - list:
import argparse
parser = argparse.ArgumentParser()
parser.add_argument('paths', type=lambda x: list(filter(str.strip,
x.split(','))))
So far so good. But this is just an example of what sort of solution I am after.
Maybe use "action" rather than "type" here? the conversion of a csv
argument into words seems more like an action.
Now the second case. I want input to be space separated array - bash array. And
I want space-separated string returned. My current approach is:
import argparse
parser = argparse.ArgumentParser()
parser.add_argument('paths', nargs='+')
args = parser.parse_args()
paths = ' '.join(args.paths)
But what I am looking for is a way to do this, which is intrinsic to `argparse`
module. Reason being I have a fair amount of such cases and I don’t want to do
post-processing, where post-post-processing happens (after
`parser.parse_args()`).
I have tried overloading `parse_args` with post-processor arguments, and that
seemed fine, but it stopped working when I had sub-parsers, which are defined
in different modules and do not call `parse_args` themselves.
Depending on what *else* you need to handle it may or not may work here
to just collect these from the remainders, and then use an action to
join them, like:
import argparse
class JoinAction(argparse.Action):
def __call__(self, parser, namespace, values, option_string=None):
setattr(namespace, self.dest, ' '.join(values))
parser = argparse.ArgumentParser()
parser.add_argument('paths', nargs=argparse.REMAINDER,
action=JoinAction)
args = parser.parse_args()
print(f"{args.paths!r}")
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