[Python-Dev] Assignment to None (original) (raw)

Benjamin Peterson musiccomposition at gmail.com
Mon Jun 9 05:10:12 CEST 2008

On Sun, Jun 8, 2008 at 9:24 PM, Curt Hagenlocher <curt at hagenlocher.org> wrote:

My apologies if this is one of those "dead horse" issues. The following seems a little inconsistent to me:

c = C() c.None Traceback (most recent call last): File "", line 1, in AttributeError: C instance has no attribute 'None' c.None = 'foo' File "", line 1 SyntaxError: assignment to None setattr(c, 'None', 'foo') c.None 'foo'

So, it's okay to setattr the attribute name "None" but not okay to set it directly? Is this deliberate or is it an unintentional side effect of parser changes to prevent assignment to None?

I believe that runtime checks like the one needed for setattr would be too much of a performance hit to be practical. The syntax changes are meant to avoid mistakes and confusion rather than completely prevent something from ever happening.

-- Cheers, Benjamin Peterson "There's no place like 127.0.0.1."

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