[Python-ideas] Nonlocal oddness

Carl Johnson carl at carlsensei.com
Mon Oct 6 08:26:59 CEST 2008

I noticed something based on some code in the other thread, but it's  
not really related to it. Is there a reason for this not working:

 >>> i = 0
 >>> def f():
...     nonlocal i
...     i += 1
...     return lambda: i
SyntaxError: no binding for nonlocal 'i' found


 >>> i = 0
 >>> def f():
...     global i
...     i += 1
...     return lambda: i

This was probably already discussed at the time "nonlocal" was  
invented, but is there a specific reason that "nonlocal" can't be used  
in cases where the next scope out is the same as "global"? I naively  
assumed that you could use them almost interchangeably if you were at  
the top level of a module. ("Almost" because "global" adds the  
variable to the module namespace if it's not already there, whereas  
"nonlocal" doesn't blithely add variables to other scopes, but just  
goes looking for existing ones.) Why force me to switch to "global"  
when I cut and paste a function out of a class or whatever and put it  
at the top level of my module? Is it just so that TOOOWTDI? Or was it  
an oversight?  Or is there some other reason?


-- Carl

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