hollowspook schrieb: > def aa(): > global b > b=b+1 > print b > > b=1 > aa() > > The above code runs well in python shell. > > However I have a problem as follows. > > new a file named test.py > ------------------------------------------------------------------------ > > def aa(): > global b > b=b+1 > print b > ------------------------------------------------------------------------- > > Then in python shell, > > from test import * > b=1 > aa() > > The error message is : > Traceback (most recent call last): > File "<interactive input>", line 1, in ? > File "test.py", line 3, in aa > b=b+1 > NameError: global name 'b' is not defined > > Why this happens? Please do me a favor.
Because python does not know "real" globals - globals are always only global on a module level. Now using the "from module import *"-syntax asks for trouble. Because your global b above is global to the __main__-module, not to the module test. But the aa-function expects it to live in tests. To make your example work, do it as this: import test test.b = 1 test.aa() See http://effbot.org/pyfaq/tutor-whats-the-difference-between-import-foo-and-from-foo-import.htm Diez
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