Re: Support for C++ under Win32

[Kevin Atkinson]

On Sun, 1 Apr 2001, Gary V. Vaughan wrote:

> On Friday 30 March 2001  3:54 am, Kevin Atkinson wrote:
> > I was wondering what the status is for supporting C++ on Win32 in the
> > multi-language branch of libtool.
>
> The g++ support for win32 should not be any worse than for other libtool
> supported platforms.

Are you referring to the MAIN branch of libtool or the multi-library
branch?  I am talking about the multi-language branch here.  In
particular the multi-language branch does not seam to support creating a
dll for g++ under Cygwin.

I currently use the multi-library branch so the building C++ libraries
works correctly without having to worry about linking in the C++ standard
library or global constructors being called.

> >  I also need ltdl to work properly under
> > Win32 so that I can dynamically load a dll at run time so that Pspell will
> > work under Win32.
>
> Apart from brokenness in the DLL design, this also more or less works.  It is
> easy if you build your project from scratch knowing you want DLL builds, but
> becomes difficult quite quickly if the package author assumed ELF type libs.

By this do you mean linking with undefined symbols?  My code uses libltdl
to load a single symbol from the module.  This symbol is a function with
C linkage which will return a new Manager class.  From that point on
inheritance is used and I never try to access any other symbols located in
that module directly.  Is this safe?

The relevant code:

  int s = lt_dlinit();
  assert(s == 0);
  PspellString libname;
  libname  = LIBDIR "/libpspell_";
  libname += name;
  libname += ".la";
  lt_dlhandle h = lt_dlopen (libname.c_str());
  if (h == 0)
    return (new PspellCanHaveErrorImpl())
      ->set_error(cant_load_module, name.c_str());
  lt_ptr_t fun = lt_dlsym (h, "new_pspell_manager_class");
  assert (fun != 0);
  PspellCanHaveError * m = (*(NewPspellManagerClass)(fun))(config, h);
  assert (m != 0);
  if (m->error_number() != 0)
    free_lt_handle(h);
  return m;

This is located in the Pspell program which you can find at
http://pspell.sourceforge.net.

---
Kevin Atkinson
kevina at users sourceforge net
http://www.ibiblio.org/kevina/