From: Kornelius Kalnbach <murphy@...>
Date: 2010-04-15T07:16:50+09:00
Subject: [ruby-core:29524] Re: [Bug #3147] gsub evaluates the passed in replacement string making results unpredictable when replacement string is dynamically generated

I use the pattern str.gsub(pattern) { replacement } when I'm not sure
about the replacement. In this case:

  'Y'.gsub(/(Y)/) { '\\' + $1 }

This specific example could also be written as:

  'Y'.gsub(/(?=Y)/, '\\')

Both avoid the backslash issue.

Escaping rules in replacement strings are indeed confusing. If you want
a single backslash in the output, you need four of them in the literal.

Adding Wayne's examples to the documentation would certainly help to
understand this.

[murphy]