From: matt@... (matt neuburg)
Date: 2009-03-16T02:17:42+09:00
Subject: can I tighten this up with block or eval?

I have here a class called ClassMaker whose greeter method returns an
instance of anonymous class containing a hello method:

class ClassMaker
  def initialize(s); @howdy = s; end
  def greeter
    c = Class.new do
      def initialize(s); @hello = s; end 
      def hello
        puts @hello # this is the nub of the matter
      end
    end
    c.new(@howdy)
  end
end

ClassMaker.new("gday").greeter.hello

I would like the anonymous class's hello method to access whatever the
value of my ClassMaker instance's @howdy ivar may be at the moment
greeter is called. I am presently doing this, as you can see, by giving
the anonymous class an initialize method and passing the @howdy ivar's
value into an ivar of the anonymous class's instance.

This works but seems heavy-handed. I feel I should be able to do it
without the anonymous class having any initialize method at all. The
whole situation has "closure" written all over it. So I tried to define
the hello method to accomplish the same thing using evals and blocks and
other tricky stuff, and became hopelessly confused. Could someone
straighten me out? Thx - m.

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