string comparison not working and throwing UnboundLocalError

Question

When using is instead of == in the first comparison statement

if host.lower() is 'localhost':

The host argument has a string called 'localhost' passed by a calling method so though the two strings are same,the control flow is running the else part of the code making the two values are not same.

If I use == instead of is than the program throws following error message.Below

To solve the issue I also defined the command variable before the if statement starts but also its not solving the problem. what exactly am I missing ?

def makeCommand(self, user, host, filepath, filteruser, sudo):
    """ 
    Two types of commands with or without ssh depends on hostname
    Adding sudo or not depends on sudo passed
    """

    if host.lower() is 'localhost':
        if sudo.lower() == 'yes':
            command = ["sudo", "cat",
                       "{filepath}".format(filepath=filepath)]
        if sudo.lower == "no":
            command = ["cat", "{filepath}".format(filepath=filepath)]
    else:
        if sudo.lower() == 'yes':
            command = ["ssh", "{user}@{host}".format(
                user=user, host=host), "sudo", "cat", "{filepath}".format(filepath=filepath)]
        else:
            command = ["ssh", "{user}@{host}".format(
                user=user, host=host), "cat", "{filepath}".format(filepath=filepath)]

    userfilter = ["egrep", "-v",
                  "\"{filteruser}\"".format(filteruser=filteruser)]

    return command, userfilter

Error:

Traceback (most recent call last):
  File "/home/tara/taraproject/checkaccessEnv/project2/plugins/plugin_etc_passwd/plugin_etc_passwd.py", line 68, in run
    self.user, self.host, self.fileloc, self.filter, self.sudo)
  File "/home/tara/taraproject/checkaccessEnv/project2/lib/sshplugin/sshplugin.py", line 34, in makeCommand
    return command, userfilter
UnboundLocalError: local variable 'command' referenced before assignment

Using `is` is *absolutely* the wrong test. They are not the same object. — Martijn Pieters, Apr 02 '17 at 10:05
What if `sudo.lower()` is neither equal to `'yes'` or `'no'`? `command` variable won't be initialized — Moinuddin Quadri, Apr 02 '17 at 10:06
The code you posted can't otherwise throw the exception, since it assigning `command` in all 4 logical branches. Are you **certain** you have not made a typo or indentation error somewhere? Make sure you are not mixing tabs and spaces, for example. — Martijn Pieters, Apr 02 '17 at 10:06
@MoinuddinQuadri: where do you see it being tested for `no`? — Martijn Pieters, Apr 02 '17 at 10:07
@MartijnPieters When `host.lower() is 'localhost'`, then there are condition to check for `yes` and `no`. But again there is typo `sudo.lower == "no"` (comparing function with string) — Moinuddin Quadri, Apr 02 '17 at 10:08
@MoinuddinQuadri: Not sure how I missed that. Yes, that's the issue right there. — Martijn Pieters, Apr 02 '17 at 10:09
Consider that variable will be initialized at anycost they will have either of the value @MoinuddinQuadri — Tara Prasad Gurung, Apr 02 '17 at 10:09
Replace `if sudo.lower == "no":` with `else`. You never called the lower method and what if the value of `sudo` is `'sure'` instead of `yes` or `no`? — Martijn Pieters, Apr 02 '17 at 10:10
@MartijnPieters putting the no in else part will work but what if its not "no" the else part will execute for any value be it not or any thing say "nothing" instead of no — Tara Prasad Gurung, Apr 02 '17 at 10:29
At the very least, replease if sudo.lower == "no" with sudo.lower() == "no", as a method object will never equal a string — Foon, Apr 02 '17 at 11:13
Possible duplicate of [double equals vs is in python](http://stackoverflow.com/questions/15008380/double-equals-vs-is-in-python) — Montmons, Apr 02 '17 at 11:41

string comparison not working and throwing UnboundLocalError

0 Answers0