[ruby-talk:14246] converting some 'eval's from perl

I'm converting some Perl code to Ruby and for the most part it's gone 
well, until I hit this problem...

I've got some files full of regex expressions that are read in by a Perl 
program and eval'ed (actually the eval is doing a pattern match against 
$_) in order to determine if a particular file matches the criteria in the 
regex.  It works like this (warning, Perl code ahead :) :

$expression = "!(/Error/ || /Abort/ || /[1-9] error/ || /fatal/)"
#actually $expression was read from one of many (thousands) of files
open(RPT,"reportfile) or die ;
while (<RPT>) {
   if(eval "$expression") {
      $found = 1;
      #other stuff....
   }
}

So 'eval "$expression"' returns a true value if $expression evaluates to 
true (in the Perl sense of truth).

Now, I'm finding that something like:

if (line =~ !(/Error/ || /Abort/ || /[1-9] error/ || /fatal/) )

just isn't going to work in Ruby for various reasons.  Technically, the 
strings in $expression (above) are not regular expressions, they are 
formulas that contain regular expressions.  

Is there any way to do this in Ruby - I really don't want to have to 
change potentially thousands of files which contain:
!(/Error/ || /Abort/ || /[1-9] error/ || /fatal/) 
to:

!/Error|Abort|[1-9] error|fatal/

(and actually, I think the '!' would still be a problem)

Phil