|In the Objective-C world there are three major runtimes: the NeXT runtime, the Apple runtime and the GNU runtime (both with and without garbage collection enabled). They are different in several respects and a program or library that works at the runtime level should be aware of them.|
|There are several Foundation libraries an application or tool can be written on top of: NeXT Foundation library which runs on NeXTStep/OPENSTEP systems, gnustep-base, libFoundation and Apple Cocoa system.|
|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 its 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:|
|nx (for NeXT), gnu (for GNU without garbage collection), gnugc (for GNU with garbage collection), apple (for Apple)|
|nx (for NeXT), gnu (for gnustep-base), fd (for libFoundation), apple (for Apple Cocoa)|
|nx (for NeXT), gnu (for gnustep-gui), apple (for Apple Cocoa)|
Runtime Foundation GUI
nx nx nx
nx fd gnu
gnu gnu gnu
gnu fd gnu
gnugc gnu gnu
gnugc fd gnu
apple apple apple
apple gnu gnu
Note that one can choose his/her own packages to build; it is not required to have all the packages installed on the system. Not having all of them installed limits only the ability to build and distribute binaries for those missing combinations.
For cross-compilation in a non-flattened directory structure is recommended, so that you can store on the same directory structure binaries for different machines. The standard GNUstep filesystem layout is normally 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:
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 using openapp, which will locate the right binary for your 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 GNUsteps Foundation 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 functionality 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 recommended 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 makefiles 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.
In order to build a project for multiple architectures youll need the development environment for the target machine installed on your machine. 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 application for another machine just by typing
$ make target=target-triplet
where target-triplet is the canonical system name as reported by config.guess.
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, its common to first source GNUstep-reset.sh to reset all shell variables, then to source GNUstep.sh again. Lets assume we use gnu-gnu-gnu as our current LIBRARY_COMBO and we want to switch to gnugc-gnu-gnu, then we would use:
Work on gnustep-make started in 1997 by Scott Christley <email@example.com>.
Version 2.0.0 of gnustep-make introduced many changes with previous releases, which was mainly the work of Nicola Pero <firstname.lastname@example.org>
This man-page was written by Dennis Leeuw <email@example.com> based on the DESIGN document from the gnustep-make source tree.
The DESIGN document was written by Ovidiu Predescu.
This work could only be as is due to the notes and corrects from Nicola Pero <firstname.lastname@example.org>.
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 notice and this notice are preserved.