> On Jan 30, 2016, at 6:04 AM, Geert Janssens <geert.gnuc...@kobaltwit.be>
> wrote:
>
> Hi,
>
> I'm adding c++ code to the csv-importer. Various classes have been defined so
> far,
> though they aren't really in use yet. They are compiled and linked into the
> csv-import
> shared lib.
>
> When running gnucash in this setup, I get this warning:
>
> WARN <gnc.module> Failed to dlopen()
> '/home/janssege/Lokaal/installs/gnucash/master/lib/gnucash/libgncmo
>
> And the csv import functionality is skipped.
>
> I understand this has to do with dlopen not understanding c++ name mangling,
> but don't
> know how to avoid it.
>
> The classes I have introduced so far don't need to be exposed to the rest of
> gnucash. They
> are intended for internal use in the csv importer only.
>
> How can I shield them from dlopen, or otherwise put, mark them as not
> exportable ?
I'm a bit puzzled about how exactly the C++ bits are integrated with the rest
of the importer, but I think your problem is that you're including C-linkage
headers into C++ without declaring them as such. For example in
gnc-csv-imp-trans.hpp, you have
#include "config.h"
#include "Account.h"
#include "Transaction.h"
#include <vector>
#include <memory>
it needs to be
extern "C"
{
#include "config.h"
#include "Account.h"
#include "Transaction.h"
}
#include <vector>
#include <memory>
to tell the compiler to use unmangled names for the symbols from those headers.
That lack of mangling is called C linkage. You need to do that in both headers
and implementations. If a header will be included in a C file, wrap the 'extern
"C" {' and closing } with #ifdef __cplusplus … #endif so that the C compiler
doesn't see it.
Any C++ functions called from C need to also have C linkage, and obviously must
be free functions, not class members. Only the declarations need be wrapped in
extern "C" {…}. The definitions shouldn't be and can be as C++-y as you want.
You can look at qof/gnc-numeric to see an example.
Regards,
John Ralls
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