From: transfire@...
Date: 2006-07-07T03:17:27+09:00
Subject: Achieving Equality

I have this fancy class:

  # Read from one and write to another.

  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

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?

T.