Igor Pechtchanski <pechtcha <at> cs.nyu.edu> writes: > The newer versions of gcc apparently allow you to link directly to a .dll > file. The .def and .a are needed for older versions of gcc, and possibly > for some other tools. > > [...] > > The reason you want an 'extern "C"' for DLL functions in general is that > g++ and the Windows C++ compilers (notably VC++) use different name > munging schemes, so a DLL built with C++ symbols won't be usable from > other applications that try to call those functions. The reason you want > it for DllMain is that the Windows loader will be looking for the unmunged > name "DllMain". Are you sure that it's really invoked when the DLL is > loaded?
Actually I found something quite interesting on a "Tcl extensions in Windows" wiki website, where a poster says that DllMain, __decl... import export, windows.h etc are no longer needed with g++. Sure enough, the following example works: 1) create a dll.h file that contains a class definition, just like you would on Unix (i.e. no __decl... macros, no extern etc) 2) create a dll.cc file that contains some of your class definition methods 3) then create the dll with g++ -c dll.o g++ -shared dll.o -otestdll.dll 4) create a testMain.cc file with a main() that #includes dll.h and uses some things defined in dll.cc 5) build with g++ -o testMain testMain.cc -L. -ltestdll 6) run testMain.exe to make sure it works Note that extern, gcc, import/export macros and declarations, DllMain etc were NOT needed. Gcc seems to export everything, like it would on *nix (except, presumably, functions declared static and things in anonymous namespace -- exercise left to the reader ;). You can tell the linker to generate a .def file by adding "-Wl,--output- def=testdll.def" when creating the testdll.dll. This shows all symbols exported. Running nm on testdll.dll also shows 67488220 T [EMAIL PROTECTED] 67481000 T [EMAIL PROTECTED] which means that gcc auto-generated it, and did not mangle for C++ use. Does anyone know if testdll.dll, created this way, would be linkable from a VC++ program? I don't have access to VC++. Oliver -- Unsubscribe info: http://cygwin.com/ml/#unsubscribe-simple Problem reports: http://cygwin.com/problems.html Documentation: http://cygwin.com/docs.html FAQ: http://cygwin.com/faq/
