Python OptParser

Question

I am trying to input a path using optparser in python. Unfortunately this piece of code keeps showing an error.

import optparse,os

parser = optparse.OptionParser()
parser.add_option("-p","--path", help = "Prints path",dest = "Input_Path", metavar = "PATH")

(opts,args) =parser.parse_args()

print os.path.isdir(opts.Input_Path)

Error :-

Traceback (most recent call last):
  File "/Users/armed/Documents/Python_Test.py", line 8, in 
    print os.path.isdir(opts.Input_Path)
  File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/genericpath.py", line 41, in isdir
    st = os.stat(s)
TypeError: coercing to Unicode: need string or buffer, NoneType found

Any help is much appreciated !

Yes I am. I am inputting it as a string but i think it gets stored as a list because when I do a for file in opts.Input_Path and print file it shows the output letter by letter for whatever I am inputting. Do you know why that is ? i just want it to print the files in the directory the path is pointing to — Amritha
– Amritha, Commented Sep 21, 2011 at 17:49
A string is an iterable object, just like a list. "for a in a_string" will loop through the characters of the string. Instead of the for loop just use the attribute opts.Input_Path itself. — ed.
– ed., Commented Sep 21, 2011 at 18:06
Here's the obligatory comment that optparse has been deprecated in favor of argparse. — GreenMatt
– GreenMatt, Commented Sep 21, 2011 at 18:18

Dave · Accepted Answer · 2011-09-21 18:00:46Z

3

That error is because opts.Input_Path is None, instead of being your path string/unicode.

Are you sure you are calling the script correctly? You should probably put in some error checking code in any case to make sure that if a user doesnt put -p, the program won't just crash.

Or, change it to a positional argument to make it 'required' by optparse: http://docs.python.org/library/optparse.html#what-are-positional-arguments-for

Edit: Also optparse is deprecated, for a new project you probably want to use argparse.

edited Sep 21, 2011 at 18:00

answered Sep 21, 2011 at 17:52

Dave

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2 Comments

Amritha Over a year ago

Will check it out ! Thanks :) Yes i was calling it the wrong way.

Dave Over a year ago

If this was the problem, you should mark one of these as an answer to let the community know : )

culebrón · Accepted Answer · 2011-09-21 17:50:43Z

2

I copied your script and ran it. Looks like you call your script in a wrong way:

 $ python test.py /tmp
 Traceback (most recent call last):
   File "test.py", line 8, in <module>
     print os.path.isdir(opts.Input_Path)
   File "/usr/lib/python2.6/genericpath.py", line 41, in isdir
     st = os.stat(s)
 TypeError: coercing to Unicode: need string or buffer, NoneType found

but

$ python test.py --path /tmp
True

answered Sep 21, 2011 at 17:50

culebrón

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