This bit of code has been in the R bindings for a few months...I use it to make a few throwaway test drivers that make it easier to write self-contained tests in the adbcdrivermanager package. I'm wondering if moving it into c/common could help us move towards a common code base for the Postgres and SQLite drivers and lower the barrier for others to contribute drivers (or just copy driver_base.h and write/maintain it themselves somewhere else).

ADBC drivers are beautifully simple things: if you can turn an std::string into an ArrowArrayStream, you have an ADBC driver. Unfortunately, there are a lot of boring details that are easy to get wrong between a would-be driver contributor and a fully functional ADBC driver. I see the "boring details that are easy to get wrong" are (1) remembering how to initialize the C callables in a drive, (2) options set/get (particularly with ADBC 1.1), and (3) error handling.

The draft I've included here lets you implement the minimal driver I described above as:

class SimpleDatabase : public adbc::common::DatabaseObjectBase {};

class SimpleConnection : public adbc::common::ConnectionObjectBase {};

class SimpleStatement : public adbc::common::StatementObjectBase {
 public:
  AdbcStatusCode SetSqlQuery(const char* query, AdbcError* error) {
    sql_query_ = std::string(query);
    return ADBC_STATUS_OK;
  }

  AdbcStatusCode ExecuteQuery(ArrowArrayStream* stream, int64_t* rows_affected,
                              AdbcError* error) {
    // Use sql_query_ to go do something
    return ADBC_STATUS_NOT_IMPLEMENTED;
  }

 private:
  std::string sql_query_;
};

using SimpleDriver =
    adbc::common::Driver<SimpleDatabase, SimpleConnection, SimpleStatement>;

AdbcStatusCode SimpleDriverInitFunc(int version, void* raw_driver, AdbcError* error) {
  return SimpleDriver::Init(version, raw_driver, error);
}

I'm happy to redo anything about this (including refactor the Postgres/SQLite drivers to use it) but wanted to pause before going further to make sure we actually want to do this!