variables - Python global scope troubles -

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i'm having trouble modifying global variables between different files in python. example:

file1.py:

x = 5

file2.py:

from file1 import *  def updatex():     global x     x += 1

main.py:

from file2 import *   updatex() print x #prints 5

there several important things note here.

first, global isn't global. global things, built-in functions, stored in __builtin__ module, or builtins in python 3. global means module-level.

second, when import *, new variables same names ones in module import *'d from, referring same objects. means if reassign variable in 1 module, other doesn't see change. on other hand, mutating mutable object change both modules see.

this means after first line of main.py:

from file2 import *

file1, file2, , __main__ (the module main script runs in) have separate x variables referring same 5 object. file2 , __main__ have updatex variables referring updatex function.

after second line:

updatex()

only file2's x variable reassigned 6. (the function has record of defined, updates file2's x instead of __main__'s.)

the third line:

print x

prints __main__'s x, still 5.


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