Hi,

isn't it possible to create several
mysqlpp::Connections? Both of them use same db, host,
user. Code below doesn't work.

class A {
A() {
mysqlpp::Connection con;
con= mysqlpp::Connection::Connection(...);
}
};

class B {
B() {
mysqlpp::Connection con;
con= mysqlpp::Connection::Connection(...);
}
};

int main() {
A a;
B b;
return 0;
}

Using g++ 4.0.4
mysql++: Version: 2.0.7-2+b1 (Debian).

It doesn't matter if con are objects or pointers.

Best regards,
Tomas.


gdb trace-back:
#0 0x080498e9 in
mysqlpp::Connection::OptionInfo:perator= ()
#1 0x08049974 in std::__copy<false,
std::random_access_iterator_tag>::copy<std::_Deque _iterator<mysqlpp::Connection::OptionInfo,
mysqlpp::Connection::OptionInfo const&,
mysqlpp::Connection::OptionInfo const*>,
std::_Deque_iterator<mysqlpp::Connection::OptionIn fo,
mysqlpp::Connection::OptionInfo&,
mysqlpp::Connection::OptionInfo*> >
()
#2 0x08049a4c in
std::__copy_aux<std::_Deque_iterator<mysqlpp::Conn ection::OptionInfo,
mysqlpp::Connection::OptionInfo const&,
mysqlpp::Connection::OptionInfo const*>,
std::_Deque_iterator<mysqlpp::Connection::OptionIn fo,
mysqlpp::Connection::OptionInfo&,
mysqlpp::Connection::OptionInfo*> > ()
#3 0x08049af0 in std::__copy_normal<false,
false>::copy_n<std::_Deque_iterator<mysqlpp::Conne ction::OptionInfo,
mysqlpp::Connection::OptionInfo const&,
mysqlpp::Connection::OptionInfo const*>,
std::_Deque_iterator<mysqlpp::Connection::OptionIn fo,
mysqlpp::Connection::OptionInfo&,
mysqlpp::Connection::OptionInfo*> > ()
#4 0x08049b9c in
std::copy<std::_Deque_iterator<mysqlpp::Connection ::OptionInfo,
mysqlpp::Connection::OptionInfo const&,
mysqlpp::Connection::OptionInfo const*>,
std::_Deque_iterator<mysqlpp::Connection::OptionIn fo,
mysqlpp::Connection::OptionInfo&,
mysqlpp::Connection::OptionInfo*> > ()
#5 0x0804c8ed in
std::deque<mysqlpp::Connection::OptionInfo,
std::allocator<mysqlpp::Connection::OptionInfo>
#7 0x0804caf2 in A::A ()
#8 0x08048afb in main ()


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------=_Part_22477_4758657.1149363889863
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Content-Disposition: inline

It would appear that the issue isn't so much multiple mysqlpp::Connections
coexisting, but an issue with the assignment operator. The stack trace you
provided indicates that your program isn't even getting to your declaration
of b. I tried running the code you provided with a few modifications to get
it to compile, and the code hung. However, by commenting out the two
assignment lines (con=3D ...) it ran and exited fine.

It appears to me that using an assignment operator on mysqlpp::Connection i=
s
a behavior which hasn't been accounted for. A few minutes of poking around
leads me to suspect that the issue is actually with Lockable (which is
inherited by Connection). In any case, I think the most expedient thing for
you to do is not use the =3Doperator. You should be able to supply whatever
arguments you need directly to the constructor.

-Drew


On 6/2/06, Tomas Fischer < tomas_fischer99 (AT) yahoo (DOT) de> wrote:
------=_Part_22477_4758657.1149363889863--

Hi,

now I using a singleton pointer and it seems to work.
But I don't understand following code:

struct A {
A() {
mysqlpp::Connection con(mysqlpp::use_exceptions);
}
};

int main() {
A a;
}

Again, a segmention fault occurs, why?
If I use con to connect to a database with
connect(...) it works.

Best regards,
Tomas

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Drew M. wrote:
Yes. The problem is that it doesn't exist.

With no defined assignment operator, you just get a bitwise copy, which
is not the right thing with Connection. You don't want a clone of the
existing connection down to the bit level, you want a new connection
with the same parameters. I've added such semantics to Connection.
This will appear in the next release of MySQL++.

Tomas, I hope you can find the time to play with the version of MySQL++
in the Subversion repository, to see if this works for you, before it
gets into a release version.

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