'How can I use a global variable in another file in Python?
I want to make i into 3 in file s2.py, but it keeps becoming 1.
File s1.py
i=1
class a():
def f():
global i
i = 3
File s2.py
from s1 import *
a.f()
print(i)
Solution 1:[1]
Every module has its own global scope, and Python is lexically scoped, meaning a.f refers to the global scope of s1 no matter where it is called from. i is initialized to the value of s1.i, but is otherwise independent of it. Changes to s1.i do not affect s2.i.
Solution 2:[2]
You have to re-import your variable after calling your method if you want to see any changes made.
#s1.py
i=1
class a():
def f():
global i
i = 3
#s2.py
from s1 import *
a.f()
from s1 import i
print(i)
Solution 3:[3]
#s1.py
i=1
class a():
def f():
global i
i += 3
#s2.py
import s1
s1.a.f()
print(s1.i)
Solution 4:[4]
I believe you are referencing the local variable i and aren't referencing the instance of i in the class. Try this.
print(a.i)
Solution 5:[5]
Reimport the variable after calling the method:
File s1.py
i = 1
class a():
def f():
global i
i += 3
File s2.py
import s1
s1.a.f()
print(s1.i)
Sources
This article follows the attribution requirements of Stack Overflow and is licensed under CC BY-SA 3.0.
Source: Stack Overflow
| Solution | Source |
|---|---|
| Solution 1 | chepner |
| Solution 2 | Andrew M. |
| Solution 3 | vexem |
| Solution 4 | Donald Duck |
| Solution 5 | Peter Mortensen |