From: "Vincent L." <like.space@...>
Date: 2008-06-04T06:09:34+09:00
Subject: instance_eval, regexp with block : losing $1

To build a wiki-like engine (or DSL) with dynamically generated
methods, I do the following :

class Base
  def self.match(name, regexp, &block)
    define_method(name) do |text|
      text.gsub!(regexp) do
        puts "$1 in match method : #{$1}"
        #block.call
        instance_eval(&block)
      end
    end
  end
end

class Foo < Base
  match :g, /(.)g$/i do
    puts "$1 in passed block : #{$1}"  #Unfortunately $1 is lost !
    'ggg'                              #so only hardcoded values :-(
  end
end

f = Foo.new
f.g('bla')   #bla
f.g('doing') #doiggg ; problem is I cannot use $1 in block

After some research I found these 2 links
http://eigenclass.org/hiki/binding.of_caller+substitute
http://blade.nagaokaut.ac.jp/cgi-bin/scat.rb/ruby/ruby-talk/202600
(BTW I am trying to avoid any third-party libraries)

But I don't manage to get these to work...
I need to get $1, $2, etc. special values
in the block I pass in Base subclasses.
How can I do that ?

Thanks,

Vincent
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