From: Gunther Diemant <g.diemant@...>
Date: 2011-12-29T23:52:19+09:00
Subject: Re: What’s the standard way of implementing #hash for value objects in Ruby?

I think you can't access instance variables from a class method, so
both methods are kinda useless.

2011/12/29 Nikolai Weibull <now@bitwi.se>:
> Hi!
>
> What’s the standard way of implementing #hash for value objects in Ruby?
>
> For
>
> class A
>  def initialize(a, b, c)
>    @a, @b, @c = a, b, c
>  end
> end
>
> is it
>
> def A.hash
>  self.class.hash ^ @a.hash ^ @b.hash ^ @c.hash
> end
>
> or
>
> def A.hash
>  self.class.hash ^ [@a, @b, @c].hash
> end
>
> or is it something else?
>
> No classes in the standard library use self.class.hash, but I think it
> makes sense to use it.
>