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[Python-Dev] Compiler treats None both as a constant and variable

Guido van Rossum guido@python.org
Sun, 30 Mar 2003 14:02:38 -0500 
> >>> def f():
>  None  
> 
> >>> dis(f)
> 2           0 LOAD_GLOBAL              0 (None)
>               3 POP_TOP             
>               4 LOAD_CONST               0 (None)
>               7 RETURN_VALUE 
> 
> >>> None = 1
> <stdin>:1: SyntaxWarning: assignment to None
> >>> f() == None
> False
> 
> 
> Is this a bug?

Yes, assigning to None is a bug. :-)

> Should the compiler use the GLOBAL in both places?

No, not until we've officially changed the rules.

> Or, is it reasonable to use CONST in both places?

No, not until assigning to None is an error rather than a warning.
This will have to wait until at least 2.4 -- the warning is new in
2.3.

--Guido van Rossum (home page: http://www.python.org/~guido/)