从python模块正确返回布尔变量

Question

I'm sure this is absurdly simple but I have been unable to get it working.

I want to convert a boolean variable to True in a module and return it to my main.

file: test

import module as mo

value = False
mo.x(value)
print(value)

2. file: module

def x(value):
    value = True
    return value

But this code is not working. When I print out the value it gives me a False . Does anybody know how to return the value so it's True ? Or is it even possible to change a boolean value in another module and return it afterwards?

Answer 1

You're not printing the return value of the funtion. For that, you should

v = mo.x(value)
print(v)

Otherwise, you're printing the local variable value .

Answer 2

You are printing out value instead of the result of mo.x(value) .

In your test.py, try the following:

import module as mo

value = False
value = mo.x(value)
print(value)

and the output will be:

>>> True

---

Note that the variables defined inside a function have a local scope. This means that value variable inside function x is only accessible within the function and is not the same as the value variable in your test.py module.

Answer 3

The problem is, that primitive types, like integers are passed by value and not by reference. So what happens is, you don't pass the variable "value" to function x(), but the value inside "value" gets copied.

A workaround would be using any object, as they are always passed by reference. Eg: A list:

value[0] = False
mo.x(value)

def x(value: list):
    value[0] = True
    return value

Answer 4

This happens because you are returning "True" value but you dont assign it to "value" variable. So, you are just making the call to the function but not using the return value.