From: "Shot (Piotr Szotkowski)" <shot@...>
Date: 2008-05-12T08:20:28+09:00
Subject: Re: Array#uniq with Hash elements... can't remove duplicates

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andrea:

> I've read on the pickaxe book that Array#uniq detects duplicates using
> the eql? method on the elements, but it doesn't seem to work even if
> I monkeypatch the Hash class:

> class Hash
>   def eql? other
>     self =3D=3D other
>   end
> end

Hashes of the objects must also match:

shot@devielle:~$ irb
>> class Hash
>>   def hash
>>     to_a.hash
>>   end
>>   alias eql? =3D=3D
?> end
=3D> nil
>> a =3D {:foo =3D> 'bar'}
=3D> {:foo=3D>"bar"}
>> b =3D {:foo =3D> 'bar'}
=3D> {:foo=3D>"bar"}
>> [a,b].uniq
=3D> [{:foo=3D>"bar"}]

That said, monkeypatching Hash in this way is a (very) bad idea.

-- Shot
--=20
Perl is more an attempt to prove strong AI by making a language so ambiguous
that humans can't parse it, yet sufficiently unambiguous that computers
*can*. The day after they succeed, the human era will be ended.       -- Nix

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