On Jul 2, 2008, at 3:56 AM, Loïc Dardant wrote:
> class User : public database::User
> {
> public:
> User(mysqlpp::sql_varchar a, mysqlpp::sql_varchar b,
> mysqlpp::sql_int c
> );
> ~User();
> void foo();
> };
In C++, if a derived class has a function with the same name as one in
the base class, the derived class's versions always hide those in the
base class. Thus, your single ctor in the derived class hides these
ctors defined in the base SSQLS:
User(); // default ctor, needed by STL containers
User(const mysqlpp::Row& row); // what your error is about
User(const mysqlpp::sql_varchar& a); // for-comparison ctor
You need to define all of these in your derivative for it to be a true
SSQLS. Their implementation can be trivial: just call the base class
ctors of the same signature, passing along the parameters directly.
Technically, the one ctor you do have hides a similar one in the base
SSQLS: the full-initialization ctor takes its parameters by const
reference, not by value. You should redefine your one existing ctor
like so:
User(const mysqlpp::sql_varchar& a, const mysqlpp::sql_varchar& b,
const mysqlpp::sql_int& c);
Failing to match this signature won't prevent good code from
compiling, but taking the parameters by reference is more efficient in
the case of stringish data types. And if you're going to take them by
reference, making them const references is simply a matter of
correctness, since you aren't actually modifying the referents.
