Re: Gtk2::MozEmbed + DOM

["muppet" <scott asofyet org>]

Torsten Schoenfeld said:
> Gtk2::MozEmbed registers custom GTypes for the enums and the flags.

ah.  wasn't sure it registered all of them.  never mind.


> If you
> change CodeGen.pm to cast the value to the proper enum/flags type, it
> works.  Patch attached.

doesn't hurt at all to do this in C, so i'd say it's a good thing in general.
should go into both HEAD and stable-1-08.


> /usr/bin/perl5.8.6: symbol lookup error:
> blib/arch/auto/Gtk2/MozEmbed/MozEmbed.so: undefined symbol:
> _Z21gperl_register_objectmPKc
>
> I've no idea what this is about.  Does the C++ linker need Glib.so to be
> linked in explicitly?  And what about this weird symbol name?  Glib
> doesn't define it.  Do you need to compile every module with c++ to make
> it work?

that's a C++ versus C linkage issue.

in C++, all symbols are mangled to include information about their argument
lists.  this is to support overloading -- more than one function with the same
name but different parameters.

however, C functions are not mangled this way.

the C++ compiler is thinking that the function is the C++ function
::gperl_register_object, when it's actually a C function.

that's where C linkage comes in.

  extern "C" void foo ();

tells the C++ compiler to look for foo as foo, not ::foo.

the G_BEGIN_DECLS and G_END_DECLS macros in all of the gnome headers do this
wrapping for you.  looks like we need it in the gtk2-perl headers, as well.

the workaround, for now, is:

  /* this XS file will be compiled with a C++ compiler: */
  extern "C" {
    #include <gtk2perl.h>
  };



-- 
muppet <scott at asofyet dot org>