From: Martin DeMello <martindemello@...>
Date: 2003-05-21T17:36:29+09:00
Subject: Re: How do I get a variable into a gsub?

Dave Oshel <dcoshel@elide.spambaffler.mac.com> wrote:
> Pardon the newbie question, but I can't seem to find how to place the 
> contents of a variable into the regexp field of a gsub.
> 
> That is:
> 
> A = "There is an N such that all such N should be in parentheses, so 
> replace any N with (N)."
> 
> 
> Ok, the specific case is trivial:
> 
> A.gsub( / N /, " (N) " )
> 
> 
> But the general case is maddening.  Obviously, I am missing something.
> 
> 
> 
> If I try:
> 
> B = "x"  # the current thing I want to match and replace
> 
> Then:
> 
> A.gsub( Regexp.compile(B), " (#{B}) " )  ==> error!

What error? All the following worked under 1.7.3:

a.gsub(/#{b}/, "(#{b})")
a.gsub(Regexp.compile(b), "(#{b})")
a.gsub(Regexp.compile(b)) {|match| "(#{match})"}

martin