Re: Link to C++ library

[Yen-Ju Chen]

 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++ ?

 Thanx again.

 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 22:38:13 +0200 (CEST)
>
>
> > From: "Yen-Ju Chen" <yjchenx@hotmail.com>
> > Date: Tue, 10 Sep 2002 15:52:52 -0400
> >
> > Hi,
> >
> >   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 ?
> >
> >   Yen-Ju
>
>
> 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.
>
> ------------------------------------------------------------------------
> include $(GNUSTEP_SYSTEM_ROOT)/Makefiles/common.make
> #GNUSTEP_INSTALLATION_DIR = $(GNUSTEP_USER_ROOT)
> GNUSTEP_INSTALLATION_DIR=$(INSTALLDIR)
>
> OBJCFLAGS += -g -Wall -DUNIX #-DSTRICT_OPENSTEP
> CFLAGS    += -g -Wall -DUNIX #-DSTRICT_OPENSTEP
> # (For now, the compilation on GNUstep with STRICT_OPENSTEP is broken).
>
> ADDITIONAL_INCLUDE_DIRS = \
>         -I. \
>         -IUtilities.subproj \
>         -I$(INSTALLDIR) \
>         -I$(INSTALLDIR)/MyCppLib/interfaces
>
> CC=g++
>
> -include GNUmakefile.preamble
>
>
> SUBPROJECTS=\
>         Utilities.subproj
>
> include $(GNUSTEP_SYSTEM_ROOT)/Makefiles/aggregate.make
>
>
> APP_NAME=YyyyTest
> YyyyTest_PRINCIPAL_CLASS=YyyyTest
> YyyyTest_APPLICATION_ICON=icon.tiff
> YyyyTest_RESOURCE_FILES=$(YyyyTest_APPLICATION_ICON)
> YyyyTest_RESOURCE_DIRS=
> YyyyTest_SUBPROJECTS=$(SUBPROJECTS)
> YyyyTest_OTHER_LIBRARIES=\
>         $(INSTALLDIR)/MyCppLib/libraries/libMyCppLib.a \
>         /usr/lib/libmcheck.a
> YyyyTest_TOOL_LIBS=$(YyyyTest_OTHER_LIBRARIES)
> YyyyTest_LIB_DIRS=
> YyyyTest_C_FILES=\
>         MyCppLibCalls.c
> YyyyTest_OBJC_FILES=\
>         YyyyTest_main.m \
>         YyyyTest.m \
>         YyyyCLog.m \
>         YyyyCTree.m \
>         YyyyVTree.m \
>         YyyyDictionary.m \
>         YyyyObject.m \
>                 YyyyLogToCallBack.m \
>                 YyyyFileDS.m \
>                 YyyyReference.m \
>                 YyyyElement.m \
>                 YyyyTree.m
>
>
> include $(GNUSTEP_SYSTEM_ROOT)/Makefiles/application.make
>
> -include GNUmakefile.postamble
>
> #END#
> ------------------------------------------------------------------------
>
> --
> __Pascal_Bourguignon__                   http://www.informatimago.com/
> ----------------------------------------------------------------------
>  The name is Baud,...... James Baud.




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