From: Tanaka Akira <akr@...>
Date: 2009-08-02T14:07:59+09:00
Subject: [ruby-core:24682] Re: [Bug #1852] Enumerable's #hash Raises 	ArgumentError When Recursive Values are Present

In article <67e307490908010125r6fa76654pa8e2224f714588fc@mail.gmail.com>,
  Run Paint Run Run <runrun@runpaint.org> writes:

> Yes. Even if it simply returned a constant for the degenerate case.
> (I'd rather a collision than an exception). To me, #hash is an
> integral part of Ruby objects. Having it raise with specific instances
> of a couple of classes just feels broken to me.
>
> Again, though, I'd prefer that the policy question be addressed before
> a fix is determined. Is it desirable that recursive values be allowed
> yet raise when standard methods are called on their container?

I think #hash can return a constant value if
* several real applications are found
* O(n) behavior by constant hash value is not a problem for the applications
* someone write a patch
* the overhead of the patch is not a problem.

Until above condition is met, I prefer the policy is undefined.
-- 
Tanaka Akira