Library combos
Library combos are compile-time decisions about which libraries and runtimes to use. Since the only other major libraries are from Apple, this applies only to Darwin and Mac OS X.
There are three libraries that can be linked to. The Objective-C runtime, the Foundation implementation, and the AppKit implementation.
Specifying which libraries to use is done with ./configure --with-library-combo=objcruntime-foundation-applicationkit. Each of the three could have either the value gnu or apple, but not all of these are implemented.
The following options are supported:
| Runtime | Foundation | AppKit |
|---|---|---|
| GNU | GNU | GNU |
| Apple | GNU | GNU |
| Apple | Apple | GNU |
| Apple | Apple | Apple |
Of these, the first and last options are recommended (all GNU or all Apple). The default when building on Darwin and OS X is apple-apple-apple. Even when GNUstep apps use the all Apple option, GNUstep extensions are available to the app.