Bugs That Bite
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Bugs That Bite

NameError: name ‘xyz’ is not defined

Trying to use a variable that doesn’t exist in python

If you try to use a variable in a python statement that hasn’t yet been declared, you’ll get an error that the value is not defined.

Simply instantiate the variable to and empty string, 0, True, False, or None depending on what is appropriate for the datatype you’re using above the line that is getting the error.


I explained the importance of using the correct data type when it comes to application security here:

This error may drive you a bit crazy if you believe that you have, in fact, defined the variable. Double check your spelling….

If you are using a variable in a function and it was defined in another function, pass the variable into the function to use it and return it if you need to retain the new value.

xyz= test(xyz)function test(xyz):
return xyz

This also threw me for a loop for a second when I got it on a line where I was defining a variale — or so I thought. I had typed this:


See the problem? Should be:


Teri Radichel

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