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pythonglobal-variables

right way to modify a variable of the main prgm in an aux prgm in python

I can't seem to find the right way to do this. I have a main module with a variable x and an auxiliary module that must be able to update x.

The following does not work:

#main.py
import aux
x=0
aux.update()

#aux.py
import main
def update():
   main.x += 1

It seems to be possible with a third module holding x:

#main.py
import aux,third
third.x = 0
aux.update()

#aux.py
import third
def update():
   third.x += 1

#third.py
x = 0

Is this third module necessary? Is there a "better way"?

Solution

  • Perhaps you could write some sort of class, make an instance of it and pass that to your update() function:

    #main.py
import aux

class Foo:
    def __init__(self, x):
    self.x = x

third = Foo(0)
print(third.x)
aux.update(third)
print(third.x)


#aux.py
def update(instance):
   instance.x += 1

    Output:

    0
1