From: Robert Klemme <bob.news@...>
Date: 2004-03-01T23:44:47+09:00
Subject: Re: UnboundMethod#hash apparently broken in 1.8.1


"Tim Sutherland" <timsuth@ihug.co.nz> schrieb im Newsbeitrag
news:slrnc43f2p.j1r.timsuth@europa.zone...
> In article <m3ad33mpjr.fsf@wobblini.net>, David Alan Black wrote:
> >Hi --
> >
> >"Robert Klemme" <bob.news@gmx.net> writes:
> >
> >> Hi all,
> >>
> >> one can't use UnboundMethod as a hash key:
> >>
> >> irb(main):001:0> class Foo; def bar;end; end
> >> => nil
> >> irb(main):002:0> Foo.instance_method( :bar )
> >> => #<UnboundMethod: Foo#bar>
> >> irb(main):003:0> a = Foo.instance_method( :bar )
> >> => #<UnboundMethod: Foo#bar>
> >> irb(main):004:0> b = Foo.instance_method( :bar )
> >> => #<UnboundMethod: Foo#bar>
> >> irb(main):005:0> a == b
> >> => true
> >> irb(main):006:0> b == a
> >> => true
> >> irb(main):007:0> a.hash == b.hash
> >> => false
> >> irb(main):008:0> a.id
> >> => 135052720
> >> irb(main):009:0> a.hash
> >> => 135052720
> >> irb(main):010:0> b.id
> >> => 135044800
> >> irb(main):011:0> b.hash
> >> => 135044800
> >>
> >> UnboundMethod#hash is broken in
> >> $ ruby --version
> >> ruby 1.8.1 (2003-12-25) [i386-cygwin]
> >>
> >> Is that fixed in a later version?
> >
> >I'm not sure why you describe it as broken.  Can you explain
> >a little further?
>
> I think he means because "a == b" but "!a.eql?(b)" and "a.hash != b.hash".

Exactly.

> It's not a bug, just a lack of a feature.

I regard it rather as a bug than a lack of a feature - but I'd agree that
it's debatable.  My point is that you can't use UnboundMethod as hash key
because of this although it would make pretty much sense.  (See the other
thread about attaching meta data to methods and classes)

Regards

    robert