From: Sean O'Halpin <sean.ohalpin@...>
Date: 2006-07-23T21:09:21+09:00
Subject: Re: Symbols vs. strings as hash_keys - interchangeable or not?

On 7/22/06, transfire@gmail.com <transfire@gmail.com> wrote:
> As Ezra points out they are not the same in Ruby. A hash key can be any
> object whatsoever. It could even be a number or another hash:
>
>   { {:a=>1} => 'yep' }
>
Not meaning to be picky ;) but your example is a bit misleading. Consider:

h1 = { {:a => 1} => 'nope'}
p h1[{:a => 1}]
#=> nil
hk = {:a => 1}
h2 = {hk => 'yep'}
p h2[hk]
#=> "yep"

The problems of using hashes as keys has come up a few times - see
e.g. ruby-talk:167185 for one solution. Or you could just use:

class Hash
  def hash
    self.to_a.hash
  end
  def eql?(other)
    hash == other.hash
  end
end

h = {{ :a => 1, :b => 2 } => 'yep'}
p h[:a => 1, :b => 2]
#=> "yep"

though to be honest I'm not sure if this has unpleasant side-effects
on any libs.

Regards,
Sean