Global variable is undefined at the module level

Post by Daiyue Weng
Hi, I defined a global variable in some function like this,
global global_var
PyCharm inspection gave me,
Global variable is undefined at the module level

There is no single way to silence that complaint and actually improve your
code; you have to provide some context: Why do you need a global at all, why
can't you (or don't want to) bind it on the module level etc.

Ned Batchelder

2016-09-13 11:47:29 UTC

Post by Daiyue Weng
Hi, I defined a global variable in some function like this,
global global_var
PyCharm inspection gave me,
Global variable is undefined at the module level
How to fix this?

It probably wants you to have a line at the top-level of the module (outside of any function) defining the variable:

global_var = None # or some other default value

--Ned.

dieter

2016-09-13 11:50:10 UTC

Post by Daiyue Weng
Hi, I defined a global variable in some function like this,
global global_var
PyCharm inspection gave me,
Global variable is undefined at the module level
How to fix this?

You define the global variable at the module level.

"global VVV" (in a function) actually does not define "VVV"
as a global variable. Instead, it tells the interpreter that
"VVV" should not be treated as a local variable but be looked up
in the "global" (usually module) namespace.

In order to define "VVV", you must assign a value to it -- either
directly in the "global" (i.e. module) namespace or in your function
(together with a "global VVV" declaration).

j***@gmail.com

2019-11-22 23:35:24 UTC

This is not accurate. I just tested this in python3 and using the global keyword allowed me to declare a variable inside the function that was then visible from the outer scope.

Post by Daiyue Weng
Hi, I defined a global variable in some function like this,
global global_var
PyCharm inspection gave me,
Global variable is undefined at the module level
How to fix this?

You define the global variable at the module level.
"global VVV" (in a function) actually does not define "VVV"
as a global variable. Instead, it tells the interpreter that
"VVV" should not be treated as a local variable but be looked up
in the "global" (usually module) namespace.
In order to define "VVV", you must assign a value to it -- either
directly in the "global" (i.e. module) namespace or in your function
(together with a "global VVV" declaration).

Pieter van Oostrum

2019-11-23 12:41:15 UTC

Post by j***@gmail.com
This is not accurate. I just tested this in python3 and using the global
keyword allowed me to declare a variable inside the function that was
then visible from the outer scope.

What do you mean by that?
Anything other than what was said here?

Post by dieter
In order to define "VVV", you must assign a value to it -- either
directly in the "global" (i.e. module) namespace or in your function
(together with a "global VVV" declaration).

... global globvar
... pass
...

globvar

Traceback (most recent call last):
File "<stdin>", line 1, in <module>
NameError: name 'globvar' is not defined

testfunc()
globvar

Traceback (most recent call last):
File "<stdin>", line 1, in <module>
NameError: name 'globvar' is not defined
... global globvar
... globvar = 1
...

globvar

Traceback (most recent call last):
File "<stdin>", line 1, in <module>
NameError: name 'globvar' is not defined