Weird import behavior

[Duncan Booth]

Tommytrojan wrote:

> import string
> import os
> 
> class T:
>     def __init__(self):
>         try:
>             print 'xxx nothing to do'
>         except ImportError:
>             print 'got an import error'
>             import os as string
> 
>         print 'xxxx string module', string
> 
> t=T()
> 
> 
> The import clause in the except statement (although never executed)
> removes the reference to the string module imported at the beginning of
> the script. Any idea why this is the case? 

Quoting the error message would have made the answer instantly clear to 
everyone, including probably yourself:

   UnboundLocalError: local variable 'string' referenced before assignment

Assigning to the variable 'string' anywhere in the function makes it a 
local variable throughout the function. Use 'global string' if you want the 
import to affect the global variable.