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Setting mutually exclusive arguments with argparse

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If you want two or more arguments to be mutually exclusive. You can use the function argparse.ArgumentParser.add_mutually_exclusive_group(). In the example below, either foo or bar can exist but not both at the same time. 

import argparse

parser = argparse.ArgumentParser()
group = parser.add_mutually_exclusive_group()
group.add_argument("-f", "--foo")
group.add_argument("-b", "--bar")
args = parser.parse_args()
print "foo = ", args.foo
print "bar = ", args.bar

If you try to run the script specifying both --foo and --bar arguments, the script will complain with the below message.

error: argument -b/--bar: not allowed with argument -f/--foo

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Parsing Command Line Arguments:
* Parsing Command Line arguments
* Hello world in argparse
* Using command line arguments with argv
* Setting mutually exclusive arguments with argparse
* Basic example with docopt
* Custom parser error message with argparse
* Conceptual grouping of arguments with argparse.add argument group
* Advanced example with docopt and docopt dispatch
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