[Python-Dev] [Python-checkins] cpython (3.2): don't use a slot wrapper from a different special method (closes #14658) (original) (raw)

Mark Shannon mark at hotpy.org
Tue Apr 24 17:36:31 CEST 2012

Benjamin Peterson wrote:

2012/4/24 Mark Shannon <mark at hotpy.org>:

I'm not happy with this fix. It's not perfect, but it's an improvement.

Admittedly code like:

class S(str): getattr_ = str._add s = S('a') print(S.b)

My typo, should be: print(s.b) (Instance not class) This doesn't work.

is a little weird. But I think it should work (ie print 'ab') properly. This works without the patch. class S(str): getattribute_ = str._add s = S('a') print(S.b)

Same typo, this does work (with correct spelling :) )

Does it? $ cat > x.py class S(str): getattribute_ = str._add s = S('a') print(S.b)

$ python3 x.py Traceback (most recent call last): File "x.py", line 4, in print(S.b) AttributeError: type object 'S' has no attribute 'b'

(Prints 'ab')

Also "slot wrapper" is a low-level implementation detail and shouldn't impact the language semantics. dict.getitem is a slot wrapper; dict.getitem is not. str.getitem is a slot wrapper; list.getitem is not. If any of these change then the semantics of the language changes.

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