sub report { print "Reporting"; };
sub add { print "Adding"; };
sub frobnicate { print "Frobnicating"; };

my %allowed_actions = (
    report     => \&report,
    add        => \&add,
    frobnicate => \&frobnicate,
    ...
);

sub handle_form {
    my $query = CGI->new();
    my $default_action = 'report';
    my $action = $query->param('action') || $default_action;

    # Sanity check
    if (not exists $allowed_actions{$action}) {
        warn "Unknown action >>$action<< attempted. Forcing to '$default_action' instead.";
        $action = $default_action;
    };
    my $code = $allowed_actions{$action};

    # Now, call the code
    $code->($query);
};