Question

I have a problem where I’m trying to use a function from another module but that function calls a debug function which checks if a global variable has a certain attribute. This global variable is not set (otherwise set using parser.parse_args) when I import the function so the function complains that the attribute doesn’t exist. For clarification:

File findfile.py:

_args = {}

def _debug(msg):
    if _TEST and _args.debug:
        print msg

def findfile(filename):
    ...
    _debug("found file")
    ...

if __name__ == "__main__":
    ...
    _args = parser.parse_args()
    ...

File copyafile.py

import findfile

findfile.findfile("file1")

This gives me

AttributeError: 'dict' object has no attribute 'debug'

Now I understand that parser.parse_args() returns a namespace (??) and that _args.debug isn’t really looking in the dict. But my question is: How can I in this situation properly assign something to _args to set the _args.debug to False?

I can not change findfile.py but I can change copyafile.py.

How are these things usually handled otherwise? What is the pythonic way of enabling debug flags in a script?

Answer 1

The findfile.py is wrong as it’s written, but can you try to make it work anyway setting your Argumentparser with something like:

parser.add_argument('debug', action='store_true')

and then with:

import findfile
findfile._args = parser.parse_args()

have your _args.debug set to False by default.

About your error:

You get AttributeError: 'dict' object has no attribute 'debug', beacuse you’re trying to access a dict like if it was a Namespace.

Maybe an example will clarify what a Namespace is:

>>> d = {'apple': 'red'}
>>> d['apple']
'red'
>>> from argparse import Namespace
>>> ns = Namespace(apple='red')
>>> ns.apple
'red'