From: dblack@...
Date: 2003-05-30T07:04:35+09:00
Subject: Re: substitution weirdness

Hi --

On Fri, 30 May 2003, Ian Macdonald wrote:

> Hi,
>
> Here's some behaviour I don't immediately understand:
>
> irb(main):119:0> foo = "'123"
> => "'123"
> irb(main):120:0> foo.gsub(/'/, "\\'")
> => "123123"
>
> Why does the apostrophe get replaced with a copy of the text that
> follows it?

What you're hitting is a special meaning of \' -- namely, the
post-match part of the match.  It's similar to the $`, $&, $'
variables (pre-match, match, post-match).

> I'm trying to replace every instance of ' with \' but it's proving very
> tricky. Nothing I can come up with seems to work, no matter how many
> backslashes I use, whether I use single or double quotes, whether or not
> I use gsub with a block, etc.

Try this:

  "'123".gsub(/'/, "\\\\'")


David

-- 
David Alan Black
home: dblack@superlink.net
work: blackdav@shu.edu
Web:  http://pirate.shu.edu/~blackdav