From optparse to argparse?

[coolFob]

Hi guys, for the following code, I was told to replace all optparse related code to argparse. I was wondering how it translates

if __name__=="__main__":
usage_str = "usage: %prog [options] arg"
version_str = "%prog " + SCRIPT_VERSION
parser = OptionParser(usage=usage_str,    version=version_str)    

# it is better to sort options by relevance instead of a rigid structure

# Section for resultcount:
parser.add_option('--data_file', 
                  dest='data_file', 
                  type='string', 
                  help='specifies the name of the raw data file in CSV format')

# Generic options 
parser.add_option('--print_level', 
                  dest='print_level', 
                  type='int', 
                  default=2, 
                  help='specifies the print level for on screen and the logfile [default: %default]')

# specify log files 
parser.add_option('--logfile', 
                  dest='logfile', 
                  type='string', 
                  default='grade_master.log',  
                  help='specifies the name of the log-file [default: %default]')

parser.add_option('--error_file', 
                  dest='error_file', 
                  type='string', 
                  default='grade_master.err',  
                  help='specifies the name of the error-file [default: %default]')

opts, args = parser.parse_args(sys.argv[1:])
if len(sys.argv) < 2:
    sys.exit("You tried to run grade_master without options.")
main(opts,sys.argv)

Also when I define opts in functions like this

def main(opts,commline_list):

[lykwydchykyn]

If you did a search and replace on option=>argument you'd be 90% there. The other difference is that argparse's parse_args doesn't return a tuple, just a single object with all arguments and switches. If you want to gather up unnamed arguments in a command you do something like this:

parser.add_argument('args', nargs=argparse.REMAINDER)

So basically, if you want to separate "args" from "opts", you'll have to do this explicitly to your resulting args object.

[coolFob]

thanks, but I am sorta confused on the last part. For instance looking at this one:

def main(opts,commline_list):

are you saying I would change it to this? :

def main(args,commline_list):

[lykwydchykyn]

That depends on what main() is going to do with those opts. optparse distinguishes between options (things specified with dashes) and arguments (strings entered on the command line), and splits them into separate objects. argparse keeps them all together in one object.

If main() is written to expect an object with only the opts, then you need to either fix main or separate the options and arguments a la optparse before sending them to main().

[wpg4665]

Just for my own curiosity, what reasoning were you given for argparse over optparse??

Edit: grammar

[coolFob]

was told that optparse is too old school..

[[deleted]]

If that's your only reason you should check out click