From: Nikolai Weibull <now@...>
Date: 2011-12-30T19:09:42+09:00
Subject: Re: What’s the standard way of implementing #hash for value objects in Ruby?

On Fri, Dec 30, 2011 at 10:44, Josh Cheek <josh.cheek@gmail.com> wrote:
> On Fri, Dec 30, 2011 at 3:09 AM, Nikolai Weibull <now@bitwi.se> wrote:

>> It would make implementing #hash, which you should/must do
>> if you implement #==, trivial, as there’s then only one way to do so.

> Delegating to the most relevant attribute still seems more trivial.

Trivial – perhaps.  Wrong – most definitely.  That you don’t seem to
understand this is what tells me that you don’t understand how #hash
should be implemented.

> I suppose one reason I take this view could be that the only viable
> scenarios I can think of for making some arbitrary object into a hash key
> are for sets and Array#uniq. For me, these scenarios are exceedingly rare,
> and have always been trivially replaced with alternative keys.

How about having them as keys in an actual Hash (which is how Sets and
Array#uniq are currently implemented)?