Op 2005-12-16, Peter Otten schreef <[EMAIL PROTECTED]>:
> Antoon Pardon wrote:
>
>> I have the following little piece of code:
>>
>> class Cfg:pass
>> #config = Cfg()
>>
>> def assign():
>> setattr(config, 'Start' , [13, 26, 29, 34])
>>
>> def foo():
>> config = Cfg()
>> dct = {'config':config, 'assign':assign}
>> exec "assign()" in dct
>> print config.Start
>>
>> foo()
>>
>>
>> When I execute this I get the following error:
>>
>> Traceback (most recent call last):
>> File "mod1.py", line 13, in ?
>> foo()
>> File "mod1.py", line 10, in foo
>> exec "assign()" in dct
>> File "<string>", line 1, in ?
>> File "mod1.py", line 5, in assign
>> setattr(config, 'Start' , [13, 26, 29, 34])
>> NameError: global name 'config' is not defined
>>
>> Now I don't understand this. In the documentation I read the following:
>>
>> If only the first expression after in is specified, it should be a
>> dictionary, which will be used for both the global and the local
>> variables.
>>
>> I provided a dictionary to be used for the global variables and it
>> contains a 'config' entry, so why doesn't this work?
>
>
> If you have a module
>
> v = 42
> def f(): return v
>
>
> and call f in another module
>
> print f()
>
> where no global variable v is defined, would you expect that call to fail?
> Of course not, but how can f look up the variable v then?
But I am not just calling. I'm using exec. And from the documentation
from exec I get the impression you can use it so that a function
will have temporarily a different reference to global namespace.
--
Antoon Pardon
--
http://mail.python.org/mailman/listinfo/python-list
