From: nobuyoshi nakada <nobuyoshi.nakada@...>
Date: 2005-10-27T17:46:17+09:00
Subject: Re: Cleaner syntax for .map (is there already a way, or ruby2 idea?)

Hi,

At Thu, 27 Oct 2005 15:05:41 +0900,
Ron M wrote in [ruby-talk:162876]:
> That sure beats C, but wouldn't it be nice if there
> were a shorthand for doing so.  I think something
> like this would be very nice:
> 
>    people[*].email_addr

What about:

  module Mappable
    class Mapper
      def initialize(obj)
        @obj = obj
      end
      def method_missing(meth, *args, &block)
        @obj.map {|i| i.send(meth, *args, &block)}
      end
    end
    def self.included(klass)
      super
      aref = klass.instance_method(:[])
      klass.module_eval do
        define_method(:[]) do |*idx|
          if idx.empty?
            Mapper.new(self)
          else
            aref[*idx]
          end
        end
      end
    end
  end

  class Array
    include Mappable
  end

  a = %w[a b c]
  p a[].upcase

-- 
Nobu Nakada