From: Jacob Fugal <lukfugl@...>
Date: 2006-07-07T03:42:40+09:00
Subject: Re: Achieving Equality

On 7/6/06, Chris Hulan <hulachr@hotmail.com> wrote:
> > I'm can't achieve equlity when:
> >
> >   a, b = 1, 1
> >   r, w = lambda{ a }, lambda{ b }
> >   rwd = RWDelegator.new( r, w )
> >   rwd == a   #=> true
> >   a == rwd   #=> false
> >
> > Any hope?
>
> I get a == rwd #=> true ?

As do I:

  $ cat test.rb
  class RWDelegator
    def initialize( read, write )
      @read = read
      @write = write
    end

    def inspect
      "#{@read.call.inspect}*"
    end

    def ==( other )
      @read.call == other
    end

    def method_missing( meth, *args, &blk )
      read = @read.call
      ditto = read.dup
      result = ditto.send( meth, *args, &blk )
      if ditto != read
        result = @write.call.send( meth, *args, &blk )
      end
      result
    end
  end

  a, b = 1, 1
  r, w = lambda{ a }, lambda{ b }
  rwd = RWDelegator.new( r, w )
  puts rwd == a
  puts a == rwd

  $ ruby -v test.rb
  ruby 1.8.4 (2005-12-24) [i386-linux]
  true
  true

Jacob Fugal