From: matz@... (Yukihiro Matsumoto)
Date: 2003-08-18T16:47:47+09:00
Subject: Re: Bug when rerouting String#gsub with a block using $1?

Hi,

In message "Re: Bug when rerouting String#gsub with a block using $1?"
    on 03/08/18, Mauricio Fern�ndez <batsman.geo@yahoo.com> writes:

|  "hello world".gsub(/(\w+)/) { print $1; $1 }; print "\n"
|
|Is this just impossible to do in Ruby?

In pure Ruby, yes.

Ah, wait.  If you don't need thread safety, you can do it as:


  "hello world".gsub(/(\w+)/) { print $1; $1 }; print "\n"
  class String
    alias :old_gsub :gsub
    def gsub(*args, &block)
      if block
        old_gsub(*args) {
          $match = $~
          eval("$~ = $match", block)    # the trick here.
          yield $&
        }
      else
        old_gsub(*args, &block)
      end
    end
  end
  "hello world".gsub(/(\w+)/) { print $1; $1 }; print "\n"

							matz.