[Tutor] Python Function Doubt

[Christian Witts]

nikhil wrote:
> Hi,
>
> I am learning Python and came across this example in the Python Online 
> Tutorial 
> (http://docs.python.org/tutorial/controlflow.html#default-argument-values)
> for Default Argument Values.
>
> ex:
>
> def  func(a, L=[ ]):
> L.append(a)
> return L
>
> print func(1)
> print func(2)
> print func(3)
>
> _O/P_
> [1]
> [1,2]
> [1,2,3]
>
> Now my doubt is,
>
> 1)  After the first function call, when ' L' (Reference to List 
> object) goes out of scope, why isn't it  destroyed ?
>
> 2) It seems that this behavior is similar to static variable logic in 
> C language.  Is it something similar ? OR
>     Is it related to scope rules in Python ?
>
>  
>  
> ------------------------------------------------------------------------
>
> _______________________________________________
> Tutor maillist  -  Tutor at python.org
> http://mail.python.org/mailman/listinfo/tutor
>   
It is a well known Python gotcha.  Take a read through the "Mutable 
defaults for function/method arguments" section of 
http://www.ferg.org/projects/python_gotchas.html#contents_item_6

Hope that helps your understanding.

-- 
Kind Regards,
Christian Witts