[...]
sub content {
    my ($section, $action) = @_;
    my $subs = {
        user_index      => \&user_index,
        user_unew      => \&user_new,
        user_uchange => \&user_change,
        user_udelete   => \&user_delete,
        user_gnew      => \&user_new,
        user_gchange => \&user_change,
        user_gdelete   => \&user_delete,

        project_index  => \&project_index,
        [...]

        section_error   => \&section_error
    };
    $tmp = $section."_".$action;

    if ( exists $subs->{$tmp} ) {
        $tmp = $subs->{$tmp};
    }
    else {
        $tmp = $subs->{'section_error'};
        $action    = $sysmsg{section_error};
    }
    $tmp->( $action );
}

sub section_error {
    $template->param( CONTENT_ERROR => 1 );
    $template->param( ERROR_HEADER => shift );
}
[...]