[Tutor] Argparse and how best to use it

[Dave Angel]

On 24/10/2013 11:38, Paradox wrote:

> I am trying to learn about argparse and how best to incorporate it into 
> my scripts.  I am using Python 2.7.5 on Ubuntu 13.10.

Welcome to python, and to python-tutor mailing list.  And thanks for
using text mode email, and for supplying both your Python version and
OS.

>
> It seems from the argparse tutorial that all the arguments are processed 
> as global variables.  Is that the standard way to do it or do you 
> normally (when doing real projects and not writing tutorials) process 
> the arguments in the main loop of the script?

Not sure which tutorial you're using, but the refernce page:
   http://docs.python.org/3.3/library/argparse.html

has some examples that are also at top-level, using globals.  I wouldn't
recommend that, as I try to minimize the number of non-const globals.

The only component that might make sense as a global is the result
dictionary, 'args'

So the first example would become:

import argparse

def parse_my_args():
     global args
     parser = argparse.ArgumentParser(description='Process some
integers.')
     parser.add_argument('integers', metavar='N', type=int,
nargs='+', help='an integer for the accumulator')
     parser.add_argument('--sum', dest='accumulate',
action='store_const', const=sum, default=max, help='sum the integers
(default: find the max)')
     args = parser.parse_args()


Technically, I should just return args, but this is the way I do it for
my own code.  Although args is technically non-const, by making it a
global, I am promising myself that nobody else will modify it once set
up.


-- 
DaveA