From: Brendan Baldwin <ruby-forum@...>
Date: 2006-07-19T07:13:10+09:00
Subject: How to preserve $~ when extending Regexp#match

Consider the following Regexp/MatchData extension, which pops a copy of 
the original Regexp into the MatchData object resulting from 
Regexp#match.  Forget for a minute *why* anyone might want to do this:

    class Regexp
      alias_method :original_match, :match
      def match(str)
        m=self.original_match(str)
        m.regexp=self unless m.nil?
        m
      end
    end
    class MatchData
      attr_accessor :regexp
    end

Because of the magical nature of the $~ global variable and its 
derivatives $&,$+,$`,$',$1-9, we wind up losing it from scope with this 
extension to the Regexp class:

  /myregexp/.match("test my regexp")
  $~ # <= nil

Is anyone out there aware of any way to set $~ in the "caller's" binding 
from within Regexp#match *without* requiring a manual call_stack to be 
implemented via set_trace_func?

Thanks!

--Brendan Baldwin :: ruby-forum@brendanbaldwin.com

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