«

Hi there. I just wondered whether anyone could recommend the correct
way I should be passing command line parameters into my program. I am
currently using the following code:

def main(argv = None):


file1= "directory1"
file2 = "directory2"


if argv is None:
args = sys.argv[1:]

if len(args) == 0:
Initialise.init(0)
Process.processCon(file1, 0)
Output.print()

for i in range(len(args)):
if args[i] == "-no":
Initialise.init(0)
Process.processCon(file2,1)
Output.print()

if args[i] == "-not":
Initialise.init(1)
Process1.process(stepStore, firstSteps)
Output.print1()



if __name__ == "__main__":
main()


Have I used bad syntax here so that a user can either run the program
with commands:
main.py
main.py -no
main.py -not

If I also wanted an option file to be passed in at the command line
for 'main.py' and 'main.py -no' what would be the best way to go about
this? I have never used Python to pass in arguments at the command
line so any help would be much appreciated.

Cheers
Chris

wrote:

> Hi there. I just wondered whether anyone could recommend the correct
> way I should be passing command line parameters into my program. I am
> currently using the following code:

<snip/>

Use the module optparse.

Diez

writes:

> I have never used Python to pass in arguments at the command line so
> any help would be much appreciated.

Your 'main()' approach is good. I'd rather have the function require
an 'argv' parameter, and have the default set only in the 'if __name__
== "__main__":' block, since that fits my ideas better about the
defaults.

def main(argv):
parse_commandline(argv)
do_cool_stuff()

if __name__ == "__main__":
from sys import argv
main(argv)

I also tend to catch SystemExit in the function, so the exit code can
be returned instead of raised; but that's outside the scope of this
thread.

For anything more advanced than unconditionally grabbing arguments in
sequence from the command line, you should investigate the 'optparse'
module <URL:http://docs.python.org/lib/module-optparse> from the
standard library.

--
\ "Holy knit one purl two, Batman!" -- Robin |
`\ |
_o__) |
Ben Finney

On Mon, 24 Sep 2007 01:04:58 -0700, cjt22 wrote:

> for i in range(len(args)):
> if args[i] == "-no":
> Initialise.init(0)
> Process.processCon(file2,1)
> Output.print()
>
> if args[i] == "-not":
> Initialise.init(1)
> Process1.process(stepStore, firstSteps)
> Output.print1()

That ``for`` loop is an anti-pattern in Python. If you want to iterate
over the elements of `args` the just do it directly instead of using an
index:

for arg in args:
if arg == '-no':
# ...

If you need the element *and* an index:

for i, arg in enumarate(args):
# ...

Ciao,
Marc 'BlackJack' Rintsch

wrote:
> Hi there. I just wondered whether anyone could recommend the correct
> way I should be passing command line parameters into my program. I am
> currently using the following code:
>
> def main(argv = None):
>
>
> file1= "directory1"
> file2 = "directory2"
>
>
> if argv is None:
> args = sys.argv[1:]
>
> if len(args) == 0:
> Initialise.init(0)
> Process.processCon(file1, 0)
> Output.print()
>
> for i in range(len(args)):
> if args[i] == "-no":
> Initialise.init(0)
> Process.processCon(file2,1)
> Output.print()
>
> if args[i] == "-not":
> Initialise.init(1)
> Process1.process(stepStore, firstSteps)
> Output.print1()
>
>
>
> if __name__ == "__main__":
> main()
>
>
> Have I used bad syntax here so that a user can either run the program
> with commands:
> main.py
> main.py -no
> main.py -not
>
> If I also wanted an option file to be passed in at the command line
> for 'main.py' and 'main.py -no' what would be the best way to go about
> this? I have never used Python to pass in arguments at the command
> line so any help would be much appreciated.

A solution using argparse (http://argparse.python-hosting.com/):

import argparse

def main(no=False, nott=False):
file1 = "directory1"
file2 = "directory2"

if nott:
print 'Initialise.init(1)'
print 'Process1.process(stepStore, firstSteps)'
print 'Output.print1()'
else:
print 'Initialise.init(0)'
if no:
print 'Process.processCon(file2, 1)'
else:
print 'Process.processCon(file1, 0)'
print 'Output.print()'

if __name__ == "__main__":
parser = argparse.ArgumentParser()
parser.add_argument('-no', action='store_true')
parser.add_argument('-not', action='store_true', dest='nott')
args = parser.parse_args()
main(no=args.no, nott=args.nott)

Note that I've used print statements since I don't have your Initialize,
Process, etc. objects. If I knew what "-no" and "-not" meant better, I
could give you a better suggestion, e.g. where you parse the 0 or 1
value for Initialize.init directly from the command line.

STeVe