[Python-Dev] __eq__ vs hash

[Guido van Rossum]

On Fri, Apr 4, 2008 at 2:46 AM, Ralf Schmitt <schmir at gmail.com> wrote:
> the news file for python 2.6 does not mention that you need to define
> __hash__ in case you define __eq__ for a class.
> This breaks some code (for me: mercurial and pyparsing).
> Shouldn't this be documented somewhere (I also cannot find it in the
> whatsnew file).

Well, technically this has always been the requirement.

What specific code breaks? Maybe we need to turn this into a warning
in order to be more backwards compatible?

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