A new example from the Python course just completed - looking at command line parameters through the
argparse module from the standard Python library (2.7 and 3.2 onwards), and XML handling through the
xml.etree.ElementTree module (2.5 onwards)
Here's code setting up an argument parser:
parser = argparse.ArgumentParser()
parser.add_argument('-a', '--all', action='store_true', help='Show all elements')
parser.add_argument('-r', '--root', action='store_true', help='Show elements at root level')
parser.add_argument('-v', action='store_true', help='Verbose')
parser.add_argument('sourcefile', nargs=1, help='File to parse')
args = parser.parse_args()
And by default,
-h and
--help are provided:
munchkin:cambx grahamellis$ ./xmlparserdemo -h 6_context.xml
usage: xmlparserdemo [-h] [-a] [-r] [-v] sourcefile
positional arguments:
sourcefile File to parse
optional arguments:
-h, --help show this help message and exit
-a, --all Show all elements
-r, --root Show elements at root level
-v Verbose
Parameters are named within the object returned by the parser, so:
if args.v:
print("Running in verbose mode on file %s " % args.sourcefile[0])
And usage lines generated if the program is run with incorrect arguments:
munchkin:cambx grahamellis$ ./xmlparserdemo -v -all 6_context.xml
usage: xmlparserdemo [-h] [-a] [-r] [-v] sourcefile
xmlparserdemo: error: argument -a/--all: ignored explicit argument 'll'
Complete program using this code
[here] ... the program goes on to handle XML data - there's a sample XML file
[here].
(written 2015-12-08, updated 2015-12-09)
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