Class を使わないでオブジェクト指向っぽいことをする

class.rb

module Kernel

  def object &definition
    # binding
    attrs = {}
    # object
    obj = proc { |attr_name|
      { :self => obj,
        :dict => function(obj) { |this| this.dict },
        :set => function(obj) { |this, attr_name, value| this.dict[attr_name.to_sym] = value }, 
        :get => function(obj) { |this, attr_name| this.dict[attr_name.to_sym] },
        :define => function(obj) { |this, func_name, &func| this.dict[func_name.to_sym] = function(this, &func) }
      }.each do |k, v|
        next if attrs.key? k
        attrs[k] = v
      end
      attrs[attr_name.to_sym]
    }
    obj.instance_eval {
      @value = self
      @attrs = attrs
      def value; @value; end
      def dict; @attrs; end
      def method_missing attr_name, *args
        attr = call(attr_name.to_sym)
        return nil unless attr
        attr.value
      end
    }
    obj.instance_eval &definition
    obj
  end
  
  def string str
  object {
      @str = str
      def to_s
        @str
      end
    }
  end
  
  def function this, &proc
    object {
      @proc = proc
      @this = this
      def apply this, *args, &blk
        @proc.call this, *args, &blk
      end
      def [] *args, &blk
        @proc.call @this, *args, &blk
      end
    }
  end

end

if __FILE__ == $PROGRAM_NAME
  require "test/unit"
  class TestBlsObjects < Test::Unit::TestCase

    def setup
    end

    def test_set
      obj = object {}
      obj.set[:hello, string("hello")]
      assert_equal obj.hello.to_s, "hello"
      assert_equal obj.get[:hello].to_s, "hello"
    end

    def test_define
      obj = object {}
      obj.define[:hello, &proc { |this, your_name|
        string "hello #{your_name}."
      }]
      assert_equal obj.hello['pasberth'].to_s, 'hello pasberth.'
    end

    def test_apply
      obj1 = object {}
      obj2 = object {}
      obj1.set[:hello, string("hello")]
      assert_equal obj2.get.apply(obj1, :hello).to_s, "hello"
    end

  end
end