From: "Hal E. Fulton" <hal9000@...>
Date: 2003-05-14T03:32:22+09:00
Subject: Re: Regexp: why does (re)* return only last repetition?

----- Original Message ----- 
From: <dblack@superlink.net>
To: "ruby-talk ML" <ruby-talk@ruby-lang.org>
Sent: Tuesday, May 13, 2003 1:21 PM
Subject: Re: Regexp: why does (re)* return only last repetition?


> I'm not sure what you mean by "interpolate again" (or reinterpolate).
> I think everything is happening just once: you've created a string
> ([a-z\]), and you're interpolating it into a regex.
> 
> > Frankly, /#{a}/ for the above string should be no different than
> > /[a-z\\]/.
> 
> Except... a is a 6-char string ([a-z\]), and the contents of the regex
> there is 7 characters :-)  There's no way for Ruby to backtrack and
> know that, when you created the string, you typed \ twice.  You might
> have produced the string this way:
> 
>   a = [91, 97, 45, 122, 92, 93].map {|c| c.chr}.join   # [a-z\]

I think what he wants is reasonable in a way...
it would be nice if there were a way to specify
a string (or a regex) that did not expand
backslashes. If there were, that would solve his
minor dilemma.

"Interpolate" is not the right word here... but
there are definitely two levels of processing
going on. For example: The sequence of characters 
"\\\\n" gets mapped internally to "\\n" and if that
in turn were used in a regex, it would be collpsed
again into \n. Correct?

What about a naive solution like this?

  class String
    def raw
      self.inspect[1..-2]
    end
  end

And then /#{myvar.raw}/ or some such. Am I way
off base here? This is untested. :)

Hal