Message 110423 - Python tracker

Message110423

Author	pitrou
Recipients	alexandre.vassalotti, belopolsky, eric.araujo, grubert, jackdied, pitrou, rhettinger, schmir, zzzeek
Date	2010-07-16.09:51:50
SpamBayes Score	1.6701617e-05
Marked as misclassified	No
Message-id	<1279273913.77.0.546482512706.issue9269@psf.upfronthosting.co.za>
In-reply-to

Content
> The test case in cycle.py tricks set into accepting mutable objects by > creating a class with default __hash__. This falls into a category of > "don't do it". I beg to differ. There is a reason we allow people to define __hash__ and that's to define arbitrary hashable types (not only immutable ones). Furthermore, the default __hash__ (equivalent to id()) is also perfectly useful in some cases. And in object-oriented designs it is very common to have reference cycles.

Content

> The test case in cycle.py tricks set into accepting mutable objects by > creating a class with default __hash__.  This falls into a category of > "don't do it".

I beg to differ. There is a reason we allow people to define __hash__ and that's to define arbitrary hashable types (not only immutable ones).
Furthermore, the default __hash__ (equivalent to id()) is also perfectly useful in some cases.
And in object-oriented designs it is very common to have reference cycles.

History
Date	User	Action	Args
2010-07-16 09:51:54	pitrou	set	recipients: + pitrou, rhettinger, belopolsky, grubert, jackdied, alexandre.vassalotti, schmir, eric.araujo, zzzeek
2010-07-16 09:51:53	pitrou	set	messageid: <1279273913.77.0.546482512706.issue9269@psf.upfronthosting.co.za>
2010-07-16 09:51:51	pitrou	link	issue9269 messages
2010-07-16 09:51:50	pitrou	create