I am writing in caller script:
from XXX import config
....
config.limit = limit
data.load_data()
where config.py has
limit = None
inside and data.py has
from .config import *
...
def load_data():
...
if limit is not None:
limit_data(limit)
I was expecting everybody is refering the same varibale limit in config.py module. Unfortunately, I see while debygging, that load_data sees None limit, despite the fact it was set before.
Why?
When you do from .config import *, you are importing a copy of limit from config into your own namespace. The limit entity that resides in config is not the same as the one you import. They reside in their own respective namespaces and are independent of each other.
As a workaround for this, consider this example:
A.py
foo = 5
def print_foo():
print(foo)
B.py
import A
A.foo = 10
A.print_foo()
Now, running B.py should give:
$ python B.py
10
Meaning, you can refer to the same variable by prepending the namespace qualifier.
For relative imports, you'd do something similar:
app/
__init__.py
A.py
B.py
In B.py, you'd call import app.A. You'd then refer to the variable as app.A.limit.
.config import * to import .config. Then, if I'm not mistaken, referring to config.limit will refer to the same item.import config, nor import .config works. First complains "no module config", second complains "Invalid syntax"