CODEWITHSUNDEEP
pythonmodulepython-import
Lorenz
Lorenz

Reputation: 306

Import functions in Python

How can i import functions that make use of a variable defined in the current file?

main.py

from functions import a

x = 1

print(a())

functions.py

def a():
    return x

Error Message

Traceback (most recent call last):
  File "c:\Users\Test\.vscode\extensions\ms-python.python-2019.4.11987\pythonFiles\ptvsd_launcher.py", line 43, in <module>
    main(ptvsdArgs)
  File "c:\Users\Test\.vscode\extensions\ms-python.python-2019.4.11987\pythonFiles\lib\python\ptvsd\__main__.py", line 410, in main
    run()
  File "c:\Users\Test\.vscode\extensions\ms-python.python-2019.4.11987\pythonFiles\lib\python\ptvsd\__main__.py", line 291, in run_file
    runpy.run_path(target, run_name='__main__')
  File "C:\Users\Test\AppData\Local\Programs\Python\Python37\lib\runpy.py", line 263, in run_path
    pkg_name=pkg_name, script_name=fname)
  File "C:\Users\Test\AppData\Local\Programs\Python\Python37\lib\runpy.py", line 96, in _run_module_code
    mod_name, mod_spec, pkg_name, script_name)
  File "C:\Users\Test\AppData\Local\Programs\Python\Python37\lib\runpy.py", line 85, in _run_code
    exec(code, run_globals)
  File "c:\Users\Test\Google Drive\Dev\Test\main.py", line 5, in <module>
    print(a())
  File "c:\Users\Test\Google Drive\Dev\Test\functions.py", line 2, in a
    return x
NameError: name 'x' is not defined

Upvotes: 1

Views: 7663

Answers (2)

gmds
gmds

Reputation: 19885

As another answer has noted, this will not work because of how Python scopes variables.

Instead, therefore, what I suggest is that you move all these variables into a separate file, e.g. constants.py:

main.py

from functions import a

print(a())

constants.py

X = 1

functions.py

from constants import X

def a():
    return X

Then, running import main prints 1.

Upvotes: 2

chepner
chepner

Reputation: 530960

There are no process-wide globals, only module-level globals. a uses functions.x, not the x in whatever global scope it is called from.

import functions
from functions import a, b, c

functions.x = 1
functions.y = 2
functions.z = 3

print(a())
print(b())
print(c())

Because Python is lexically scoped, each function keeps a reference to the global scope in which it was defined. Name lookups use that scope to resolve free variables.

Upvotes: 0

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