Perl Regex Question

I've been using /e to execute code with something I've captured in regular expressions. Like so:

$string =~ s{(tExT)}
            { do_something($1) }eg;

However, I've been wondering if there's anything else I can do in there. Like for example, could I use if-statements in there?

>>3
Well if it didn't work then it doesn't work I guess.

Gee did you ever learn the Scientific Method when you went to school or didn't you go at all?