Message 68937 - Python tracker

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In-reply-to
Author	ncoghlan
Recipients	amaury.forgeotdarc, barry, eikeon, glyph, gvanrossum, jek, ncoghlan, rhettinger, schmir
Date	2008年06月29日.08:34:32
SpamBayes Score	0.0032423593
Marked as misclassified	No
Message-id	<1214728474.72.0.79643113404.issue2235@psf.upfronthosting.co.za>

Content
Well, I think I figured out why the __hash__ changes were backported from Py3k: without them, the existence of object.__hash__ makes the Hashable ABC completely useless (every newstyle class meets it). I see two options here. Option 1 is to revert the changes so __hash__ behave entirely as it did in 2.5 and also delete collections.Hashable from 2.6 (which may break other backported Py3k items). Doesn't seem like a particularly good idea. Option 2 is what I have implemented locally (and will be uploading soon): changing typeobject.c to allow Py_None to be stored in type method slots, and have it convert correctly to None at the Python level. Classes that don't want to inherit the default object.tp_hash implementation can then write "__hash__ = None" or "(hashfunc)Py_None" to block the inheritance.

Content

Well, I think I figured out why the __hash__ changes were backported
from Py3k: without them, the existence of object.__hash__ makes the
Hashable ABC completely useless (every newstyle class meets it).
I see two options here. Option 1 is to revert the changes so __hash__
behave entirely as it did in 2.5 and also delete collections.Hashable
from 2.6 (which may break other backported Py3k items). Doesn't seem
like a particularly good idea.
Option 2 is what I have implemented locally (and will be uploading
soon): changing typeobject.c to allow Py_None to be stored in type
method slots, and have it convert correctly to None at the Python level.
Classes that don't want to inherit the default object.tp_hash
implementation can then write "__hash__ = None" or "(hashfunc)Py_None"
to block the inheritance.

History
Date	User	Action	Args
2008年06月29日 08:34:35	ncoghlan	set	spambayes_score: 0.00324236 -> 0.0032423593 recipients: + ncoghlan, gvanrossum, barry, rhettinger, amaury.forgeotdarc, schmir, jek, eikeon, glyph
2008年06月29日 08:34:34	ncoghlan	set	spambayes_score: 0.00324236 -> 0.00324236 messageid: <1214728474.72.0.79643113404.issue2235@psf.upfronthosting.co.za>
2008年06月29日 08:34:33	ncoghlan	link	issue2235 messages
2008年06月29日 08:34:32	ncoghlan	create

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