Yu-Xi Lim wrote:
> Steven Bethard wrote:
>> import argparse # http://argparse.python-hosting.com/
>> import subprocess
>> import sys
>
> Why not the standard lib's optparse?
The page referenced above gives a variety of reasons, but the two most
important things in this example are: argparse supports parsing of both
positional and optional arguments, and argparse generates better usage
messages.
Since argparse supports positional arguments, I can write something like::
parser.add_argument('packages', ..., nargs='+', ...)
and then the arparse module will enforce that at least one positional
argument was given. With optparse, you'd do something like:
options, args = parser.parse_args()
if not args:
parser.error('wrong number of arguments')
Basically, with optparse, anything that involves positional arguments
has to be handled by the user.
It's also worth pointing out the better usage messages. Notice that the
output looked like::
$ scriptname.py -h
usage: scriptname.py [-h] [--save SAVE] package [package ...]
positional arguments:
package one of the packages to install
optional arguments:
-h, --help show this help message and exit
--save SAVE a file to save the package names to
With the optparse, you'd get something like::
$ scriptname.py -h
usage: scriptname.py [OPTIONS]
options:
-h, --help show this help message and exit
--save SAVE a file to save the package names to
The argparse module knows how to create a meaningful usage message
instead of just "%prog [OPTIONS]", and the argparse module knows about
positional arguments, so you can have help messages for them too.
Ok, enough propaganda for now. ;-)
STeVe
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