my %actions = (
	ADD = \&add,
	DELETE = \&delete,
	REMOVE = \&remove,
);

# ...

if($action =~ /$monitoredActions/) {
	$_ = uc($action);
	if(exists $actions{$_}) {
		$actions{$_}->();
	} else {
		# undefined action. die/warn whatever
	}
}

sub add { ... }
sub delete { ... }
sub remove { ... }