import xxx from xxx import xx and modify variables are introduced inside the pit module

There are several modules as follows:
A.py
Function: Define a global variable, for use by other modules

name = "张三"
lists = [1, 2, 3, 4, 5]

B.py
features: variable print A.py in

from A import name,lists
def test():
    print("B:",name)
    print("B:",lists)

main.py

from A import name,lists
from B import test

if __name__ == '__main__':
    print("修改前-main:",name)
    name = "李四"
    print("修改后-main:", name)
    print("main:",lists)
    
    lists.append(100)
    # B模块中test的功能是打印A模块的name、lists
    test()
 
"""
修改前-main: 张三
修改后-main: 李四
main: [1, 2, 3, 4, 5]
B: 张三
B: [1, 2, 3, 4, 5, 100]
"""

After the run we found:

• A module name is modified, but printed in the module B or the original value.
• A module lists adding new elements displayed properly.

the reason:

• Using from A import name is a name created in the current block variable that points to a value A module name variable points, i.e. Zhang, modify the value of the name is actually a reference to modify the name, the string is immutable type , name = "John Doe", was created in memory of John Doe string, and then redirected name John Doe, so before Joe Smith has not changed.
• And it is a list of lists, is a variable type, so add a new element in the list is feasible, but lists can not be reassigned, and its reference will change when the re-assignment.

Solution:

• The definitions of global variables used A.py import import.

Like this:
B.py

import A
def test():
    print("B:",A.name)
    print("B:",A.lists)

main.py

import A
from B import test

if __name__ == '__main__':
    print("修改前-main:",A.name)
    A.name = "李四"
    print("修改后-main:", A.name)
    print("main:",A.lists)

    A.lists.append(100)
    # B模块中test的功能是打印A模块的name、lists
    test()
"""
修改前-main: 张三
修改后-main: 李四
main: [1, 2, 3, 4, 5]
B: 李四
B: [1, 2, 3, 4, 5, 100]
"""