Re: Link to C++ library

[Yen-Ju Chen]

 Which version of GCC are you using ? I use 3.0.4.
 How can you compile .c using g++ and .m using gcc
 in the same GNUmakefile ?
 If I use CC=gcc++ at the beginning,
 it will complain that g++ unrecognize option '-MP'
 and cc1obj invalide option '-fconstant-string-class=NSConstantString'
 Here is what I have:

 g++ main.m -c \
      -MMD -MP -DGNUSTEP -DGNUSTEP_BASE_LIBRARY=1 ...
      -o shared_objc/ix86/freebsd/gnu-gnu-gnu/main.o
       ...

 So I use CC=gcc to get the .o file first.
 Then use CC=g++ again, I got the error in previous message...

 So weird... need to look into it....

 Yen-Ju

> From: Pascal Bourguignon <pjb@informatimago.com>
> Reply-To: <pjb@informatimago.com>
> To: yjchenx@hotmail.com
> CC: help-gnustep@gnu.org
> Subject: Re: Link to C++ library
> Date: Tue, 10 Sep 2002 23:28:28 +0200 (CEST)
>
> > From: "Yen-Ju Chen" <yjchenx@hotmail.com>
> > Date: Tue, 10 Sep 2002 16:55:52 -0400
> >
> >
> >   Thanx a lot. It helps.
> >   But can I directly link Objective-C to C++ throught
> >   the C interface which the C++ library offers ?
> >
> >   After apply the CC=g++, the error message becomes
> >
> >   .../libgnustep-base.so: undefined reference to '__objc_msg_forward'
> >   .../libgnustep-base.so: undefined reference to '__objc_msg_thread_add'
> >   .../libgnustep-base.so: undefined reference to 
> '__objc_msg_thread_remove'
> >
> >   Or do I need to write a C library as the bridge between Objective-C 
> and
> > C++ ?
>
> You seem to be missing the  Objective-C runtime. I still use a GNUstep
> some months old,  but it's makefiles automatically cite  -lobjc on the
> link line.  I have something like:
>
>  g++ -rdynamic \
>       -o MyApp.app/ix86/linux-gnu/gnu-gnu-gnu/MyApp \
>       shared_obj/ix86/linux-gnu/gnu-gnu-gnu/MyObjects.o ... \
>       -L/home/pascal/GNUstep/Libraries/ix86/linux-gnu/gnu-gnu-gnu \
>       -L/home/pascal/GNUstep/Libraries/ix86/linux-gnu \
>       -L/local/gnustep/Local/Libraries/ix86/linux-gnu/gnu-gnu-gnu \
>       -L/local/gnustep/Local/Libraries/ix86/linux-gnu \
>       -L/local/gnustep/Network/Libraries/ix86/linux-gnu/gnu-gnu-gnu \
>       -L/local/gnustep/Network/Libraries/ix86/linux-gnu \
>       -L/local/gnustep/System/Libraries/ix86/linux-gnu/gnu-gnu-gnu \
>       -L/local/gnustep/System/Libraries/ix86/linux-gnu \
>       -L/local/gnustep/System/Libraries/ix86/linux-gnu \
>       -lgnustep-gui -lgnustep-base -lobjc \
>       -lz -lcallback -lavcall -lxml2 -lz -lm -lgmp -lpthread -ldl -lm \
>       $(MyApp_OTHER_LIBRARIES)
>
>
> >   Thanx again.
> >
> >   Yen-Ju
> >
> > >From: Pascal Bourguignon <pjb@informatimago.com>
> > >Date: Tue, 10 Sep 2002 22:38:13 +0200 (CEST)
> > > > From: "Yen-Ju Chen" <yjchenx@hotmail.com>
> > > > Date: Tue, 10 Sep 2002 15:52:52 -0400
> > > >
> > > >   I try to use the id3lib (http://www.id3lib.org), which is a
> > > >   C++ library, but offer the C interface.  But I met a problem
> > > >   about linking between id3lib and standard C++  library.  Is it
> > > >   possible to use such C++ library with C interface in GNUstep ?
> > >
> > >I  do  link  routinely   C++  libraries  into  GNUstep  /  Objective-C
> > >applications without any problem, passing thru a C interface.
> > >
> > >Here  is an example  of GNUmakefile  I used  lately. The  only notable
> > >thing  is  the  use  of  the  g++ compiler  (CC=g++)  to  compile  the
> > >MyCppLibCalls.c  file, which  contains  only simple  C functions  each
> > >sending  a message  to a  C++ object  from libMyCppLib.a,  which  is a
> > >library of C++ objects.
>
>
> --
> __Pascal_Bourguignon__                   http://www.informatimago.com/
> ----------------------------------------------------------------------
>  The name is Baud,...... James Baud.




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