From: Sebastian Hungerecker <sepp2k@...>
Date: 2009-04-26T20:37:52+09:00
Subject: Re: Overriding eql? and hash

César Díaz wrote:
> def hash
>     StringUtils.nice_slug(self.name, "false").hash
>
>   end
>
>   def eql?(other)
>     equal = false
>     if StringUtils.nice_slug(self.name, "false").downcase.eql?
> StringUtils.nice_slug(other.name, "false").downcase
>       equal = true
>     end
>     equal
>   end

If two strings are equal except for case your eql? method will return true. Or 
at least it would if it ever got called. But since you don't call downcase in 
the hash method, those two objects will have different hash values and Set 
will never bother to call eql? on them.
In other words: call downcase in the hash method as well and you'll be fine.

HTH,
Sebastian