From: andrew.oxenburgh@...
Date: 2007-12-12T00:07:03+09:00
Subject: Set and Object equivilence

Hi,

I've just started with Ruby from Java, and am having trouble getting a
set to recognise equivalence between objects. Basically it is adding
multiple equal objects to the set.

I have created a class and overridden all of the operators <=> , ==,
<, >, eqls?, equals?, hash to indicate that it should use an internal
variable to compare.

Please find enclosed a unit test, the object, and the output from the
test. Cool language BTW. Really enjoying it up until this moment. I'm
probably missing some subtlety of the language.

Any help greatly appreciated.
-------- source starts --------

require "test/unit"
require "set"

class JunkTest < Test::Unit::TestCase
    def test_arraysMuckingAroundWith
        a = Thingy.new(1)
        b = Thingy.new(2)
        c = Thingy.new(1)
        d=Set.new
        d << a
        d << b
        d << c
        puts "output set, with duplicates - the first 2 object should
be equivilent" + d.sort.to_s
    end
end

class Thingy

    attr_accessor :value

    def <=> (thing)
        self.value <=> thing.value
    end

    def == (thing)
        self.value == thing.value
    end

    def > (thing)
        self.value > thing.value
    end

    def < (thing)
        self.value < thing.value
    end

    def eqls? (thing)
        self.value.eqls?(thing.value)
    end

    def equals? (thing)
        self.value.equals?(thing.value)
    end

    def initialize(val)
        @value = val
    end

    def hash
        puts "hash " + @value.hash.to_s
        @value.hash
    end

    def to_s
        value.to_s + ", "
    end
end
-------- source ends --------

-------- output starts --------

C:\dev\ruby\bin\ruby.exe -e
"STDOUT.sync=true;STDERR.sync=true;load($0=ARGV.shift)" C:/projects/
SearchJars/test/JunkTest.rb --name test_arraysMuckingAroundWith
Loaded suite C:/projects/SearchJars/test/JunkTest
Started
hash 3
hash 5
hash 3
output set, with duplicates - 1, 1, 2,
.
Finished in 0.0 seconds.

1 tests, 0 assertions, 0 failures, 0 errors

Process finished with exit code 0

-------- output ends --------

Regards



Andrew Oxenburgh