get qr/(?<greet>hi|hello)/ => sub {
    print $+{greet}, " there!\n";
}

##</code><code>##

$ cat pm_1198334.pl
#!env perl

my @handlers;
sub get {
    my ($key, $action) = @_;
    push @handlers, [ $key, $action ];
}

sub handle {
    my $request = shift;

    for my $rh (@handlers) {
        my ($key, $action) = @$rh;

        if ("Regexp" eq ref $key) {
            return $action->($request) if $request =~ $key;
        }
        elsif ("" eq ref $key) {
            return $action->($request) if $key eq $request;
        }
        else {
            print "How do I handle <", ref($key), ">?\n";
        }
    }

    print "Sorry, I don't know what <$request> means!\n";
}

get foo => sub { print "Pizza time!\n" };
get qr/(?<greet>hi|hello)/ => sub { print $+{greet}, " there!\n" };

handle("foo");
handle("hi robot!");
handle("helloooooooo Nurse!");

Roboticus@Waubli ~
$ perl pm_1198334.pl
Pizza time!
hi there!
hello there!