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library-combo(7)	     GNUstep System Manual	      library-combo(7)

NAME
       library-combo - GNUstep Make support for	cross-compilation.

DESCRIPTION
       This manual page	is about cross-compilation and fat binaries. Fat bina-
       ries are	packages that you can supply which contain more	the one	binary
       of  your	 program  (e.g.	your application). So you can support multiple
       platforms with a	single package.

       To support this your system has to be built  in	a  non-flattened  way.
       Meaning	that  during  the installation of gnustep-make you should have
       selected	--disable-flattened and	the types of library combinations  you
       want  to	support, through the --with-library-combo option. With library
       combinations we mean the	Objective-C runtime,  the  Foundation  library
       and  the	 Application  library. For more	details	about this see the LI-
       BRARY-COMBO section.

       If you installed	your GNUstep system in a non-flattened way all	system
       dependend binaries are installed	in subdirectories with cpu/os/library-
       combo information. That means for instance that	the  gnustep-base  li-
       brary  will  be	installed in Library/Libraries/ix86/linux/gnu-gnu-gnu/
       when you	are on an Intel	x86 system, running linux with the GNU runtime
       for Objective-C and you installed GNUstep.

       For  each  and  every library-combo that	you want to support you	should
       create the environment through gnustep-make, because it installs	a dif-
       ferent config.make to support its own CC, OPTFLAGS, etc.	flags.

   LIBRARY-COMBO
       An important issue is to	let to a package the ability to	deal with var-
       ious libraries and configurations available now:

       Objective-C runtimes
	      In the Objective-C world there are  three	 major	runtimes:  the
	      GNUstep runtime, the Apple runtime and the GNU runtime. They are
	      different	in several respects and	 a  program  or	 library  that
	      works at the runtime level should	be aware of them.

       Foundation libraries
	      There  are different Foundation libraries	an application or tool
	      can be written on	top of:	gnustep-base, libFoundation and	 Apple
	      Cocoa system.

       Graphical interfaces
	      Until  now  three	 libraries  provide or try to provide OpenStep
	      compliant	systems: the AppKit from NeXT, gnustep-gui  and	 Cocoa
	      from Apple.

       If  a  program wants to work with all the possible combinations it will
       have to provide different binaries for each  combination	 because  it's
       not possible to have a tool compiled for	NeXT Foundation	that runs with
       gnustep-base or vice-versa. To summarize, a program can be compiled for
       these combinations:

       Objective-C runtime
	      ng (for GNUstep Next Generation with nonfragile API and ARC sup-
	      port etc), gnu (for GNU ,	or for GNUstep without latest language
	      features), apple (for Apple), nx (for NeXT)

       Foundation library
	      gnu (for gnustep-base), fd (for libFoundation), apple (for Apple
	      Cocoa), nx (for NeXT Foundation)

       GUI library
	      gnu (for gnustep-gui), apple (for	Apple  Cocoa),	nx  (for  NeXT
	      GUI)

       We'll  denote  the  fact	that an	application was	compiled for a certain
       combination of the above	values by using	the abbreviations of the  dif-
       ferent  subsystems  and placing dashes between them. For	example	an ap-
       plication compiled for NeXT Foundation using NeXT AppKit	will have  the
       compile	attribute  nx-nx-nx.  An  application compiled for Apple Cocoa
       with the	GNU compiler for Objective-C gnu-apple-apple and  another  one
       compiled	 for gnustep-base using	gnustep-gui under Unix will be denoted
       by gnu-gnu-gnu. Here is a list of some of the possible combinations:

	  Runtime     Foundation     GUI
	    nx		  nx	     nx
	    nx		  fd	     gnu
	    gnu		  gnu	     gnu
	    ng		  gnu	     gnu
	    gnu		  fd	     gnu
	   apple	 apple	     apple
	   apple	  gnu	     gnu

       Note that one can choose	his/her	own packages to	build; it is  not  re-
       quired to have all the packages installed on the	system.	Not having all
       of them installed limits	only the ability to build and distribute bina-
       ries for	those missing combinations.

   DIRECTORY STRUCTURE
       For  cross-compilation in a non-flattened directory structure is	recom-
       mended, so that you can store on	the same directory structure  binaries
       for different machines.	The standard GNUstep filesystem	layout is nor-
       mally used when a non-flattened directory structure is being used; this
       is  obtained  with  the	--with-layout=gnustep  option when configuring
       gnustep-make.  The entire GNUstep installation is then  created	inside
       /usr/GNUstep  (or another directory if you use the --prefix=...	option
       when configuring	 gnustep-make).	  Directories  that  contain  binaries
       (such  as  the Libraries	directory) inside /usr/GNUstep are then	set up
       to support fat binaries as follows:

       Libraries/
	 ix86/
	   linux-gnu/
	     gnu-gnu-gnu/
		 libgnustep-base.so
		 libgnustep-gui.so
	     gnu-fd-gnu/
		 libFoundation.so
		 libgnustep-gui.so

       To allow	the right libraries to be found, you need to source GNUstep.sh
       before  using GNUstep, and you need to start up your application	by us-
       ing openapp, which will locate the right	binary for your	library	combo.

   BUILDING FOR	A LIBRARY-COMBO
       The makefile package will allow the user	to  choose  between  different
       library	combinations. To specify a combination you want	to compile for
       just type:

	 $ make	library_combo=library-combo

       For instance if you want	to choose to compile using the GNUstep's Foun-
       dation  implementation  and  use	the GNUstep GUI	library	on a GNU/Linux
       machine you can do like this:

	 $ make	library_combo=gnu-gnu-gnu

       If your project requires	running	configure before compiling  there  are
       two  issues  you	have to	keep in	mind. 'configure' is used to determine
       the existence of	particular header files	and/or of some specific	 func-
       tionality  in  the  system  header files. This thing is usually done by
       creating	a config.h file	 which	contains  a  couple  of	 defines  like
       HAVE_...	which say if the checked functionality is present or not.

       Another	usage  of configure is to determine some specific libraries to
       link against to and/or some specific tools. A typical  GNUstep  program
       is  not required	to check for additional	libraries because this step is
       done by the time	the makefile package  is  installed.  If  the  project
       still  needs to check for additional libraries and/or tools, the	recom-
       mended way is to	output a config.mak file which is included by the main
       GNUmakefile,  instead  of using Makefile.in files which are modified by
       configure.  The reason for not doing this is to avoid having the	 make-
       files contain target dependencies like above, this way keeping only one
       makefile	instead	of several for each target machine.

       The makefile package is written for GNU make because it	provides  some
       very  powerful  features	that save time both in writing the package but
       also at runtime,	when you compile a project.

   BUILDING FOR	AN ARCHITECTURE
       In order	to build a project for multiple	architectures you'll need  the
       development  environment	 for  the target machine installed on your ma-
       chine. This includes a cross-compiler together with all the  additional
       tools  like  the	 assembler and linker, the target header files and all
       the libraries you need.

       The GNUstep makefile package should be able to compile and link an  ap-
       plication for another machine just by typing

	 $ make	target=target-triplet

       where  target-triplet  is the canonical system name as reported by con-
       fig.guess.

   USING A LIBRARY-COMBO
       When you	use library-combos, you	must always source  GNUstep.sh.	  That
       allows you to switch library paths on the fly. If you want to switch to
       a different library-combo in your shell,	and if	you  are  using	 bash,
       it's  common  to	first source GNUstep-reset.sh to reset all shell vari-
       ables, then to source GNUstep.sh	again. Let's assume we use gnu-gnu-gnu
       as  our current LIBRARY_COMBO and we want to switch to ng-gnu-gnu, then
       we would	use:

	 . /usr/GNUstep/System/Library/Makefiles/GNUstep-reset.sh
	 export	LIBRARY_COMBO=ng-gnu-gnu
	 . /usr/GNUstep/System/Library/Makefiles/GNUstep.sh

SEE ALSO
       debugapp(1), GNUstep(7),	gnustep-config(1), openapp(1)

HISTORY
       Work on gnustep-make started in 1997 by	Scott  Christley  <scottc@net-
       community.com>.

       Version 2.0.0 of	gnustep-make introduced	many changes with previous re-
       leases, which was mainly	the work of Nicola Pero	 <nicola.pero@meta-in-
       novation.com>

AUTHORS
       This man-page was written by Dennis Leeuw <dleeuw@made-it.com> based on
       the DESIGN document from	the gnustep-make source	tree.

CREDITS
       The DESIGN document was written by Ovidiu Predescu.

       This work could only be as is due to the	notes and corrects from	Nicola
       Pero <nicola.pero@meta-innovation.com>.

COPYRIGHT
       Copyright (C) 2007 Free Software	Foundation, Inc.

       Copying	and  distribution  of this file, with or without modification,
       are permitted in	any medium without royalty provided the	copyright  no-
       tice and	this notice are	preserved.

gnustep-make			  20/12/2007		      library-combo(7)

NAME | DESCRIPTION | SEE ALSO | HISTORY | AUTHORS | CREDITS | COPYRIGHT

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