You may use (?{ code }), with the perlre-warning in mind:
WARNING: This extended regular expression fea­ ture is considered highly experimental, and may be changed or deleted without notice.

An example:

#!/usr/bin/perl
package Test;

sub test {
    return 'test_1';
}

package main;
if ( 'test_1' =~ m/(?{ Test::test() })/) {
    print "ok\n";
} else {
    print "not ok\n";
}
__END__
ok
[download]

regards,
tomte

Hlade's Law:

If you have a difficult task, give it to a lazy person --
they will find an easier way to do it.