package Foo;

sub new {
    my $class    = shift;
    my $dbh      = ...
    my $subclass = "$class::$dbh->{Driver}{Name}";

    eval "use $subclass; 1;"
        or croak "$dbh->{Driver}{Name} is unsupported";
    
    bless { dbh => $dbh }, $subclass;
}

sub dbh {
    $_[0]->{dbh};
}

##</code><code>##

package Foo::mysql;

sub insert_id {
    my $self = shift;
    $self->dbh->{mysql_insertid};
}

###########
package Foo::Pg;

## notice how Pg requires the table and column, while the
## other DBDs ignore these args

sub insert_id {
    my ($self, $table, $col) = @_;
    my $id;

    eval {
        my $seq = $table . '_' . $col . '_seq';
        my $sth = $self->dbh->prepare( "select currval('$seq')" );
        $sth->execute;
        ($id) = $sth->fetchrow_array;
        $sth->finish;
        1;
    } or die;
    
    return $id;
}

##########
package Foo::SQLite;

sub insert_id {
    my $self = shift;
    $self->dbh->func('last_insert_rowid');
}