On Wed, Sep 11, 2013 at 10:50 PM, chandan kumar <chandan_...@yahoo.co.in> wrote:
> In Test2.py file I wanted to print the global value ,Debug_Value as 10.I'm
> not getting expected result.Please can any one point where exactly i'm doing
> wrong.
>
> Similarly , how can i use global variable inside a class and use the same
> value of global variable in different class?Is that possible?if Yes please
> give me some pointers on implementing.
Python simply doesn't have that kind of global. What you have is
module-level "variables" [1] which you can then import. But importing
is just another form of assignment:
# Test1.py
Debug_Value = " "
# Test2.py
from Test1 import *
# is exactly equivalent to
Debug_Value = " "
It simply sets that in Test2's namespace. There's no linkage across.
(By the way, I strongly recommend NOT having the circular import that
you have here. It'll make a mess of you sooner or later; you actually,
due to the way Python loads things, have two copies of one of your
modules in memory.) When you then reassign to Debug_Value inside
Test1, you disconnect it from its previous value and connect it to a
new one, and the assignment in the other module isn't affected.
Here's a much simpler approach:
# library.py
foo = 0
def bar():
global foo
foo += 1
# application.py
import library
library.bar()
print(library.foo)
This has a simple linear invocation sequence: you invoke the
application from the command line, and it calls on its library. No
confusion, no mess; and you can reference the library's globals by
qualified name. Everything's clear and everything works.
ChrisA
[1] They're not really variables, they're name bindings. But close
enough for this discussion.
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