Short docopt presentation done at pyuggre.

1. DOCOPT
A convenient way to parse your command line
arguments

2. I have developed a super script
Now I need to get arguments and options from
user command line

3. There are several possibilities
Raw argv parsing
Getopt
Argparse
Docopt
...

4. Raw argv parsing
#!/usr/bin/python
import sys
# Get command line parameters
def usage():
print('{} usage:n'.format(sys.argv[0]))
print('bidule: do somethin great.')
if('bidule' in sys.argv):
print('Bidule')
if('­h' in sys.argv):
usage()
Do not use that !

5. Getopt
C-style parser for command line options
import getopt, sys
def usage():
print('{} usage:n'.format(sys.argv[0]))
print('bidule: do somethin great.')
def main():
try:
opts, args = getopt.getopt(sys.argv[1:], "ho:v",
["help", "output="])
except getopt.GetoptError as err:
print str(err); usage(); sys.exit(2)
output = None; verbose = False
for o, a in opts:
if o == "­v":
verbose = True
elif o in ("­h", "­­help"):
usage(); sys.exit()
elif o in ("­o", "­­output"):
output = a
else:
assert False, "unhandled option"
# ...
if('bidule' in args):
print('Bidule')
if __name__ == "__main__":
main()
Old style parsing !

6. Argparse
Python build in module
import argparse
parser = argparse.ArgumentParser()
parser.add_argument("square",
type=int,
help="display the square of a given number"
parser.add_argument("­v",
"­­verbosity",
action="count",
help="increase output verbosity")
args = parser.parse_args()
answer = args.square ** 2
if args.verbosity == 2:
print "the square of {} equals {}".format(args.square,
elif args.verbosity == 1:
print "{}^2 == {}".format(args.square, answer)
else:
print answer

7. Argparse
Usage automatically created
$ python argparse_sample.py -h
usage: argparse_sample.py [-h] [-v] square
positional arguments:
square display the square of a given number
optional arguments:
-h, --help show this help message and exit
-v, --verbosity increase output verbosity

8. Argparse
Super powerful but...
"Complex"
Focus on code and not usage

9. Docopt
Write the usage first !
Usage within program docstring
Unix usage style

10. Docopt
Example
#!/usr/bin/env python
# ­*­ coding: utf­8 ­*­
"""
docopt_sample.py
Display the square of a given number
Usage:
docopt_sample.py <square>
docopt_sample.py (­h | ­­help)
docopt_sample.py ­­version
Options:
­h ­­help Show this screen.
­­version Show version.
<square> : number to square
"""
from docopt import docopt
from pprint import pprint
arguments = docopt(__doc__, version='1.0')
pprint(arguments)
</square></square>

11. Docopt
More complex example...
#!/usr/bin/python
# coding=utf­8
'''
redfish­client ::
Usage:
redfish­client [options] config add <manager_name> <manager_url> [<login>] [<password>]
redfish­client [options] config del <manager_name>
redfish­client [options] config modify <manager_name> (manager_name | url | login | password) <changed_value>
redfish­client [options] config show
redfish­client [options] config showall
redfish­client [options] manager getinfo [<manager_name>]
redfish­client [options] chassis getinfo [<manager_name>]
redfish­client [options] system getinfo [<manager_name>]
redfish­client (­h | ­­help)
redfish­client ­­version
Options:
­h ­­help Show this screen.
­­version Show version.
­c ­­config FILE Configuration file
­i ­­inventory FILE Configuration file [default: $HOME/.redfish/inventory]
­­insecure Ignore SSL certificates
­­debug LEVEL Run in debug mode, LEVEL from 1 to 3 increase verbosity
Security warning LEVEL > 1 could reveal password into the logs
­­debugfile FILE Specify the client debugfile [default: $HOME/.redfish/redfish­client.log]
­­libdebugfile FILE Specify python­redfish library log file [default: $HOME/.redfish/python­redfish.log]

12. Docopt
And output...
{'­­config': None,
'­­debug': None,
'­­debugfile': '$HOME/.redfish/redfish­client.log',
'­­help': False,
'­­insecure': False,
'­­inventory': '$HOME/.redfish/inventory',
'­­libdebugfile': '$HOME/.redfish/python­redfish.log',
'­­version': False,
'<changed_value>': None,
'<login>': None,
'<manager_name>': None,
'<manager_url>': None,
'<password>': None,
'add': False,
'chassis': False,
'config': True,
'del': False,
'getinfo': False,
'login': False,
'manager': False,
'manager_name': False,
'modify': False,
'password': False,
'show': False,
'showall': True,
'system': False,
'url': False}
</password></manager_url></manager_name></login></changed_value>

13. Docopt
Weaknesses
Need an external module
Sphinx documentation
Less accurate than argparse
PEP compliance (E501)

14. THANK YOU !
René Ribaud <rene.ribaud@hpe.com>