In the following code (web CGI app), I enable users to define some text and a search+replace regex that they wish to run. It's important to be able to include backreferences in the replacement text. I've been able to accomplish this with the use of eval(), but unfortunately it is a performance problem. I also tried using the /e (evaluation) switch, but that did not permit variable interpretation in the replacement text.

So my big question is: how do I do this *without* eval()?

Here's my code sample: 
$user_defined_string = "abcabcabc";
$user_defined_search = '(a)';
$user_defined_replace = '---$1---';

print "before: $user_defined_string\n";
eval("\$user_defined_string =~ s/$user_defined_search/$user_defined_re
+place/gs;");
print "after: $user_defined_string\n";

[download]
Note that $user_defined_string, $user_defined_search, and $user_defined_replace change for each invocation.

thanks!
-Nept

In reply to How to do regex backreferences within $variable replacement text? by ManFromNeptune

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