Accepting arguments by argparse

Question

What is the Difference between nargs='*' and nargs='+' ?

As they both accept one or more arguments.

parser.add_argument('nums',narg='*')

And

parser.add_argument('nums',narg='+')

Answer 1

argparse is following the common usage in re syntax. quoting from https://docs.python.org/3/library/re.html

* Causes the resulting RE to match 0 or more repetitions of the preceding RE, as many repetitions as are possible. ab* will match 'a', 'ab', or 'a' followed by any number of 'b's.

+ Causes the resulting RE to match 1 or more repetitions of the preceding RE. ab+ will match 'a' followed by any non-zero number of 'b's; it will not match just 'a'.

? Causes the resulting RE to match 0 or 1 repetitions of the preceding RE. ab? will match either 'a' or 'ab'.

https://docs.python.org/3/library/argparse.html#nargs

You can also use argparse constants, which have the same string values

argparse.ONE_OR_MORE
argparse.ZERO_OR_MORE
argparse.OPTIONAL