From: Paul Lutus <nospam@...>
Date: 2006-12-15T09:05:06+09:00
Subject: Re: Restricted capture in Regexp

Benjohn Barnes wrote:

/...

> I would like gsub's block or second parameter to
> provide an array, and for this to replace the captured parts of the
> regexp, so:
> 
> "axb".gsub(/(.)x(.)/, ['A', 'B'])
> 
> would return:
> 
> "AxB"
> 
> gsub doesn't behave like this, but I imagine it would be possible to
> build a gsub like function that did. :)

result = "axb".gsub(/(.)(x)(.)/, "A\\2B" ) # gets what you want.

> It would probably need to 
> inspect the regular expression given to it with a regular expression.

Not really. Each of sub(), gsub() and scan() have their niche. It is more a
matter of learning how to use them.

And, now that I think about it, your example using a provided array of
replacement values can be implemented like this:

rep = ['A', 'B']

result = "axb".gsub(/(.)(x)(.)/, "#{rep[0]}\\2#{rep[1]}")

And, I am sure, in many other ways.

-- 
Paul Lutus
http://www.arachnoid.com