How to make a variable's late binding crosses the module boundary?

[Jach Feng]

Richard Damon 在 2022年8月29日 星期一上午10:47:08 [UTC+8] 的信中寫道：
> On 8/27/22 7:42 AM, Mark Bourne wrote: 
> > Jach Feng wrote: 
> >> I have two files: test.py and test2.py 
> >> --test.py-- 
> >> x = 2 
> >> def foo(): 
> >>      print(x) 
> >> foo() 
> >> 
> >> x = 3 
> >> foo() 
> >> 
> >> --test2.py-- 
> >> from test import * 
> >> x = 4 
> >> foo() 
> >> 
> >> ----- 
> >> Run test.py under Winows8.1, I get the expected result: 
> >> e:\MyDocument>py test.py 
> >> 2 
> >> 3 
> >> 
> >> But when run test2.py, the result is not my expected 2,3,4:-( 
> >> e:\MyDocument>py test2.py 
> >> 2 
> >> 3 
> >> 3 
> >> 
> >> What to do? 
> > 
> > `from test import *` does not link the names in `test2` to those in 
> > `test`.  It just binds objects bound to names in `test` to the same 
> > names in `test2`.  A bit like doing: 
> > 
> > import test 
> > x = test.x 
> > foo = test.foo 
> > del test 
> > 
> > Subsequently assigning a different object to `x` in one module does 
> > not affect the object assigned to `x` in the other module. So `x = 4` 
> > in `test2.py` does not affect the object assigned to `x` in `test.py` 
> > - that's still `3`.  If you want to do that, you need to import `test` 
> > and assign to `test.x`, for example: 
> > 
> > import test 
> > test.x = 4 
> > test.foo() 
> >
> Yes, fundamental issue is that the statement 
> 
> from x import y 
> 
> makes a binding in this module to the object CURRECTLY bound to x.y to 
> the name y, but if x.y gets rebound, this module does not track the changes. 
> 
> You can mutate the object x.y and see the changes, but not rebind it. 
> 
> If you need to see rebindings, you can't use the "from x import y" form, 
> or at a minimum do it as: 
> 
> 
> import x 
> 
> from x import y 
> 
> then later to get rebindings to x.y do a 
> 
> y = x.y 
> 
> to rebind to the current x.y object. 
> 
> -- 
> Richard Damon
Yes, an extra "import x" will solve my problem too! Sometimes I am wondering why "from x import y" hides x? hum...can't figure out the reason:-)

--Jach