From: Mark Probert <probertm@...>
Date: 2003-01-11T05:13:34+09:00
Subject: regexp question


Hi, again, Rubyists.

Below is code that does multiple substitutions on a block of
text, using a recursive call to a regexp.  The output is like:

   s1 = {\aa TEXT:}  It is {\bb amazing} what a {\xx regexp} can do
   s2 = <alpha>TEXT:</alpha>  It is <beta>amazing</beta> what a 
<xx>regexp</xx> can do


The trouble is I am getting the following warning (repeated 3 times)

   warning: string pattern instead of regexp; metacharacters no longer 
effective

when I run the code. The warning comes from the line in the code that reads

   s = str.sub(match[0], ssub)

This expression works (no warnings) outside the function.  Any ideas as to
why this is happening and how I can get around the warning?

BTW, is the a better way of doing this task?

Regards,

-mark.

---< code >----

def rformat(rfmt,str)
   fmt = rfmt.slice(-2, 2)  # take the last 2 characters only
   s = ''
   case fmt
   when "aa" then s = "<alpha>#{str}</alpha>"
   when "bb" then s = "<beta>#{str}</beta>"
   else          s = "<#{fmt}>#{str}</#{fmt}>"
   end
   return s
end

$re = Regexp.compile(/(\{\\[a-z]+)\s([^\}]*)(\})/)

def rexp(str)
   match = $re.match(str)
   return str if match.nil?

   ssub = rformat(match[1], match[2])
   s = str.sub(match[0], ssub)

   rexp(s)   # recurse to find more patterns
end


s1 = '{\aa TEXT:}  It is {\bb amazing} what a {\xx regexp} can do'
puts "s1 = #{s1}"
s2 = rexp(s1)
puts "s2 = #{s2}"