From: Daniel Harple <dharple@...>
Date: 2006-04-11T20:07:37+09:00
Subject: Re: Duplicity in Set

On Apr 11, 2006, at 12:28 PM, Radek Skokan wrote:

> I have a Set which should contains elements of my object Component.  
> The
> component class implements method hash. I'm gathering data, createing
> Componets from them and storing it into the Set. It's a Set just to  
> prevent
> duplicates. But finally the Set contains duplicate elemets -- with  
> the same
> hash value.

You must implement #eql? and #hash --

require 'set'

class Component
   attr_accessor :attributes
   attr_reader :name, :subcomponents
   def initialize(name)
     @name = name
     @attributes = {}
     @subcomponents = []
   end
   def inspect() %{<%s hash=%#x @name=%s>} % [self.class.name,  
self.hash, @name.inspect] end
   def eql?(other) @name.eql?(other.name) end
   def hash() @name.hash end
end

components = Set.new
components << Component.new("foo")
components << Component.new("bar")
components << Component.new("foo")
components.each { |c| puts c.inspect }

-- Daniel