python argparser for multiple arguments for partial choices
argparse, python
Solution
To elaborate on the subparser approach:
sp = parser.add_subparsers(dest='a')
x = sp.add_parser('x')
y=sp.add_parser('y')
z=sp.add_parser('z')
x.add_argument('-b', required=True)
- this differs from your specification in that no `-a` is required.
- `dest='a'` argument ensures that there is an 'a' attribute in the namespace.
- normally an optional like '-b' is not required. Subparser 'x' could also take a required positional.
If you must use a `-a` optional, a two step parsing might work
p1 = argparse.ArgumentParser()
p1.add_argument('-a',choices=['x','y','z'])
p2 = argparse.ArgumentParser()
p2.add_argument('-b',required=True)
ns, rest = p1.parse_known_args()
if ns.a == 'x':
p2.parse_args(rest, ns)
A third approach is to do your own test after the fact. You could still use the argparse error mechanism
parser.error('-b required with -a x')
Problem
I create a argparser like this: ``` parser = argparse.ArgumentParser(description='someDesc') parser.add_argument(-a,required=true,choices=[x,y,z]) parser.add_argument( ... ) ``` However, only for choice "x" and not for choices "y,z", I want to have an additional REQUIRED argument. For eg. ``` python test -a x // not fine...needs additional MANDATORY argument b python test -a y // fine...will run python test -a z // fine...will run python test -a x -b "ccc" // fine...will run ``` How can I accomplish that with ArgumentParser? I know its possible with bash optparser