* GNUstep Backend
Each of these packages needs to be built and installed on your Linux system in order to gain access to the full power of Objective-C and to be able to work with the examples in the remainder of this book. Fortunately a single package called ''GNUstep Startup'' is provided that contains the source code for all four of the above packages. This package can be downloaded from the [http://wwwmain.gnustep.org/resources/downloads.php?site=ftp%3A%2F%2Fftp.gnustep.org%2Fpub%2Fgnustep%2F#core GNUstep.org website download page]. be Be sure to download the latest ''stable'' release of the ''GNUstep StarterStartup'' software.
Once the package has been download to a suitable work folder it can be unpacked as follows (where <version> is replaced by the version number of the package you downloaded):
</pre>
Exception encountered, of type "Error"
[6075021c] /index.php/Special:MobileDiff/8464 Error from line 434 of /var/www/techotopia/includes/diff/DairikiDiff.php: Call to undefined function each()
Backtrace:
#0 /var/www/techotopia/includes/diff/DairikiDiff.php(544): DiffEngine->diag()
#1 /var/www/techotopia/includes/diff/DairikiDiff.php(344): DiffEngine->compareSeq()
#2 /var/www/techotopia/includes/diff/DairikiDiff.php(227): DiffEngine->diffLocal()
#3 /var/www/techotopia/includes/diff/DairikiDiff.php(721): DiffEngine->diff()
#4 /var/www/techotopia/includes/diff/DairikiDiff.php(859): Diff->__construct()
#5 /var/www/techotopia/includes/diff/DairikiDiff.php(980): MappedDiff->__construct()
#6 /var/www/techotopia/extensions/MobileFrontend/includes/diff/InlineDiffFormatter.php(99): WordLevelDiff->__construct()
#7 /var/www/techotopia/includes/diff/DiffFormatter.php(140): InlineDiffFormatter->changed()
#8 /var/www/techotopia/includes/diff/DiffFormatter.php(82): DiffFormatter->block()
#9 /var/www/techotopia/extensions/MobileFrontend/includes/diff/InlineDifferenceEngine.php(117): DiffFormatter->format()
#10 /var/www/techotopia/includes/diff/DifferenceEngine.php(797): InlineDifferenceEngine->generateTextDiffBody()
#11 /var/www/techotopia/includes/diff/DifferenceEngine.php(728): DifferenceEngine->generateContentDiffBody()
#12 /var/www/techotopia/extensions/MobileFrontend/includes/specials/SpecialMobileDiff.php(241): DifferenceEngine->getDiffBody()
#13 /var/www/techotopia/extensions/MobileFrontend/includes/specials/SpecialMobileDiff.php(135): SpecialMobileDiff->showDiff()
#14 /var/www/techotopia/extensions/MobileFrontend/includes/specials/MobileSpecialPage.php(53): SpecialMobileDiff->executeWhenAvailable()
#15 /var/www/techotopia/includes/specialpage/SpecialPage.php(384): MobileSpecialPage->execute()
#16 /var/www/techotopia/includes/specialpage/SpecialPageFactory.php(553): SpecialPage->run()
#17 /var/www/techotopia/includes/MediaWiki.php(281): SpecialPageFactory::executePath()
#18 /var/www/techotopia/includes/MediaWiki.php(714): MediaWiki->performRequest()
#19 /var/www/techotopia/includes/MediaWiki.php(508): MediaWiki->main()
#20 /var/www/techotopia/index.php(41): MediaWiki->run()
#21 {main}