Multi-python modules share the same variable

Mechanism Python import package is import incoming and module systems are placed in sys.modulethe dictionary inside

Py import multiple files at a time, will go to sys.modulewhether there has been import inspection, and if you have import, the import will not repeat, otherwise import came

from aaa.yyy import xIs not the same, test.py in this way from import, then x is test their own namespace of variables. So x is only valid in test.py in any case for x changes can not affect the x yyy

That is
from yyy import x
equivalent to

improt yyy
x= yyy.x  # 当你执行x=2时，完全影响不到yyy.x

So, if you need shared variables, do not use this form yyy import x from, but the use of import file, then can be used by yyy.x, then yyy.x = 'abc' can be modified. Such treatment of global variables can be shared. That is, to maintain a separate namespace, this does not import python again to achieve sharing.

Example:

# 目录树
multi_module
│  main.py
│  val_sync.py

# val_sync.py
DICT = {
    'a':1,
    'b':2,
}

# main.py
import val_sync as mv
print(mv.DICT)
mv.DICT['c'] = 3
print(mv.DICT)
mv.DICT.pop('a')
print(mv.DICT)

python main.py
out:
{'a': 1, 'b': 2}
{'a': 1, 'b': 2, 'c': 3}
{'b': 2, 'c': 3}