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From:Graham Reitz Date:August 6 2007 9:48pm
Subject:Re: multiple definitions of symbol linker error using sql_create_#
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Ok I see what is going on now.

 From another post:

 > To fix this, I would put the sql_create_* macro in a separate .h  
file,
 > and #define MYSQLPP_SSQLS_NO_STATICS above all #includes for that  
file
 > except for one.  This ensures that the static members are assigned to
 > only once.  You can see this pattern in action in the examples: the
 > 'stock' SSQLS type is defined in stock.h, and it is included in both
 > util.cpp and in custom*.cpp

That is an unfortunate thing to have to do, especially if you will be  
sharing a library with other developers.  Now they have to 'remember'  
to do this.  Easy enough to do, but when you get busy it can be easy  
to forget or overlook.

Thanks,
Graham


On Aug 6, 2007, at 4:21 PM, William F. Dowling wrote:

> Put something like this in the project .h file (say, projdb.h):
>
> #ifndef PROJ_DB_CPP
> #define MYSQLPP_SSQLS_NO_STATICS
> #endif
>
> and something like this in the one corresponding .cpp file
>
> #define PROJ_DB_CPP
> #include "projdb.h"
> #undef  PROJ_DB_CPP
>
> This caught me up too; search the mail archives for a fuller
> explanation.
>
> Will
>
>
> On Mon, 2007-08-06 at 16:14 -0500, Graham Reitz wrote:
>> I created a header file where I placed all of my sql_create_# macros.
>>
>> I keep getting multiple definition linker errors.
>>
>> /usr/bin/ld: multiple definitions of symbol agencies::names
>> (there are more, but similar)
>>
>> What am I missing?
>>
>> The code looks as follows:
>>
>> // start file my_tables.h
>> #include <mysql++.h>
>> #include <custom.h>
>> #include <string>
>>
>> #ifndef _TABLES_HPP_
>> #define _TABLES_HPP_
>>
>> sql_create_3(agencies, 1, 3,
>>                unsigned int,          agency_id,
>>                std::string,           agency_name,
>>                std::string,           agency_contact)
>>
>> sql_create_3(billing, 1, 3,
>>                unsigned int,         billing_id,
>>                std::string,          billing_agency_name,
>>                std::string,          billing_first_name)
>> #endif // _TABLES_HPP_
>> // end file my_tables.h
>>
>> // start file my_db.h
>> #ifndef _MY_DB_H_
>> #define _MY_DB_H_
>>
>> #include <string>
>> #include <vector>
>>
>> #include <boost/noncopyable.hpp>
>> #include "my_tables.h"
>>
>> class my_db : boost::noncopyable
>> {
>> public:
>>      explicit my_db(std::string tcp_ip_address, unsigned int
>> port_number,
>>                      std::string db_name, std::string db_username,
>>                      std::string db_password);
>> };
>> #endif // _MY_DB_H_
>> // end file my_db.h
>>
>> // start file my_db.cpp
>> #include <mysql++.h>
>> #include "tac_db.h"
>>
>> my_db::my_db(std::string tcp_ip_address, unsigned int port_number,
>>                 std::string db_name, std::string db_username,
>>                 std::string db_password)
>> {
>>      // Connect to the database
>>      mysqlpp::Connection connection(db_name.c_str(),
>> tcp_ip_address.c_str(),
>>          db_username.c_str(), db_password.c_str(), port_number,  
>> false);
>> }
>> // end file my_db.cpp
>>
>>
>>
>>
> -- 
> William F Dowling
> william.dowling@stripped
> www.scientific.thomson.com
>
> -- 
> MySQL++ Mailing List
> For list archives: http://lists.mysql.com/plusplus
> To unsubscribe:    http://lists.mysql.com/plusplus? 
> unsub=grahamreitz@stripped
>


Thread
multiple definitions of symbol linker error using sql_create_#Graham Reitz6 Aug
  • Re: multiple definitions of symbol linker error using sql_create_#William F. Dowling6 Aug
    • Re: multiple definitions of symbol linker error using sql_create_#Graham Reitz6 Aug
  • Re: multiple definitions of symbol linker error using sql_create_#Graham Reitz6 Aug
  • Re: multiple definitions of symbol linker error using sql_create_#Graham Reitz6 Aug
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          • RE: MYSQLPP problem in visual studio : mysqlpp.dll was not found !!!Jim Wallace7 Aug
            • RE: MYSQLPP problem in visual studio : mysqlpp.dll was not found !!!Ian Daysh7 Aug
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