Cannot call function from within imported function

Question

I have 2 files, the first is named function_call_test.py and contains the following code;

from Strategy_File import strategy

def function_1():
    print('This works')

strategy()

The second file is called Strategy_File.py and contains the following code;

def strategy():
    print('got here')
    function_1()

When running the first script I get 'NameError: name 'function_1' is not defined'. I thought that when you imported a function that it was added to the importing modules namespace. If that is the case why can't strategy() see function_1()?

Just as importantly, how do I make this work. The above is for demo purposes only, I have reasons for wanting strategy() to be in a separate module.

Python 3.6, Windows 7-64, Visual Studio 2019 and IDLE

Is there really not a duplicate for this?

Karl Knechtel
– Karl Knechtel

2021-08-13 22:19:58 +00:00
Commented Aug 13, 2021 at 22:19 — Karl Knechtel
– Karl Knechtel, Commented Aug 13, 2021 at 22:19

chepner · Accepted Answer · 2021-08-13 22:11:12Z

4

Python is statically scoped. Lookup for a free variable (such as function_1) proceeds though the scopes where strategy is defined, not where it is called. As strategy is defined in the global scope of the module Strategy_File, that means looking for Strategy_File.function_1, and that function is not defined.

If you want strategy to call something in the current global scope, you need to define it to accept a callable argument, and pass the desired function when you call strategy.

# Strategy_File.py

# f is not a free variable here; it's a local variable
# initialized when strategy is called.
def strategy(f):
    print('got here')
    f()

and

# function_call_test.py

from Strategy_File import strategy


def function_1():
    print('This works')

# Assign f = function_1 in the body of strategy
strategy(function_1)

edited Aug 13, 2021 at 22:11

answered Aug 13, 2021 at 22:05

chepner

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Comments

Code-Apprentice · Accepted Answer · 2021-08-13 22:04:56Z

0

You have to import every name into the file where it is used. So you need to modify Strategy_File.py to this:

from function_call_test import function_1

def strategy():
    print('got here')
    function_1()

But now you encounter a new problem: circular imports. Python won't allow this. So you will have to figure out a different way to organize your functions.

answered Aug 13, 2021 at 22:04

Code-Apprentice

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2 Comments

DisappointedByUnaccountableMod Over a year ago

You’re right, but you haven’t actually answered the question have you. This is more like a comment.

Code-Apprentice Over a year ago

@balmy The question answers how to fix the NameError. Someone else explains how to fix the circular import, so I'll leave it at that.

pooldiver69 · Accepted Answer · 2021-08-13 22:10:55Z

0

This error caused by Strategy_File.py is missing definition of function_1().

~~adding this line in Strategy_File.py on the top will helps.~~

edit: circular imports will not help. sorry for the misinformation.

edited Aug 13, 2021 at 22:10

answered Aug 13, 2021 at 22:05

pooldiver69

92 bronze badges

4 Comments

Silvio Mayolo Over a year ago

Python doesn't allow circular imports, so OP needs something like dependency injection to fix this.

Code-Apprentice Over a year ago

While this solves the immediate error, it leads to another error.

chepner Over a year ago

Circular imports are fine, as long as you don't need a value defined in one module in order to define the other.

pooldiver69 Over a year ago

ah, you guys are right. Did pay attention that function 2 is called in the first file. edited. sorry for this misinformation.

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