From: Marnen Laibow-Koser <marnen@...>
Date: 2010-01-14T00:56:35+09:00
Subject: Re: Ruby Regex

Robert Klemme wrote:
> 2010/1/13 Brian Candler <b.candler@pobox.com>:
>>> irb(main):038:0> a.gsub(/&/,"\\&")
>> => "\\&0\\&1"
> But it's only special when preceded by a backslash, which is special
> in replacement strings.
> 
> irb(main):002:0> "123".gsub(/\d/, '<&>')
> => "<&><&><&>"
> irb(main):003:0> "123".gsub(/\d/, '<\\&>')
> => "<1><2><3>"
> irb(main):004:0> "123".gsub(/\d/, '<\\\\&>')
> => "<\\&><\\&><\\&>"
> 
> Another example - backslash with group index:
> 
> irb(main):011:0> "abc".gsub(/\w(.)\w/, '<1>')
> => "<1>"
> irb(main):012:0> "abc".gsub(/\w(.)\w/, '<\\1>')
> => "<b>"
> irb(main):013:0> "abc".gsub(/\w(.)\w/, '<\\\\1>')
> => "<\\1>"
> 
> So what you basically do here is you escape the escape so it looses
> its special meaning in the replacement string. :-)

...and Ruby's stupid backslash handling strikes again.  This is a 
completely brain-dead way to do it, and is one of the few things I 
really hate about Ruby.

> 
> Kind regards
> 
> robert

Best,
-- 
Marnen Laibow-Koser
http://www.marnen.org
marnen@marnen.org
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