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[ANN] GNUstep Objective-C Runtime 1.5

From: David Chisnall
Subject: [ANN] GNUstep Objective-C Runtime 1.5
Date: Wed, 20 Jul 2011 15:28:37 +0100

Hi Everyone,

I've just pushed the 1.5 release of libobjc2 (yes, I said I would do this a 
week ago, but PyObjC uncovered a couple of bugs that I wanted to fix first).  
Thanks to Niels, Quentin, Sebastian, Wolfgang, Ludovic, and everyone else who 
helped me find and fix bugs and test new features.

This is an important release for GNUstep, because it's one of the few times 
when we're not playing catchup with Apple.  This release of the runtime 
supports all of the Objective-C language features supported by the compiler 
that Apple ships for OS X 10.7 and iOS 5 under the brand Apple's LLVM Compiler 

This includes support for automatic reference counting, which is now the 
default development mode for OS X and is fully supported by the runtime, in 
combination with LLVM / Clang trunk.


[1] Actually a snapshot of LLVM / Clang trunk from between 2.9 and 3.0.  LLVM 
releases don't always happen at convenient times for Apple, so the use their 
own release numbers.  

GNUstep Objective-C Runtime 1.5

This is the sixth official release of the GNUstep Objective-C runtime (a.k.a.
libobjc2).  This runtime was designed to support the features of Objective-C 2
for use with GNUstep and other Objective-C programs.  Highlights of this
release include:

- Support for Apple-compatible garbage collection APIs, along with extensions
  to support CoreFoundation-style explicit reference counting in a garbage
  collected environment.  This uses the Boehm garbage collector and is enabled
  by specifying boehm_gc=yes when building.  This requires version 7.1 or later
  of libgc.  Code compiled with -fobjc-gc can be mixed with code that
  implements normal reference counting and with code compiled with
  -fobjc-gc-only.  The runtime supports both GC and non-GC code when compiled
  with GC support and will automatically select the correct behavior depending
  on the loaded code.

- The runtime will now use Boehm GC for several internal data structures, if it
  is built with GC enabled.  This avoids the need for defensive programming
  with respect to thread safety in several places.

- This is the first release to provide a superset of the functionality provided
  by the Mac Objective-C runtime, as shipped with OS X 10.6.

- Full support for Automatic Reference Counting (ARC), compatible with OS X
  10.7 and iOS 5, including support for __weak references.

- The LLVM optimisation passes have been improved and better tested.  Code
  compiled with them now passes the EtoileFoundation test suite.

You may obtain the code for this release from subversion at the following
subversion branch:


Alternatively, a tarball is available from:


The runtime library is responsible for implementing the core features of the
object model, as well as exposing introspection features to the user.  The
GNUstep runtime implements Apple's Objective-C Runtime APIs, and a small number
of GCC APIs for legacy compatibility.

This library is based on the Étoilé Objective-C Runtime, an earlier research
prototype, and includes support for non-fragile instance variables,
type-dependent dispatch, and object planes.  It is fully compatible with the
FSF's GCC Objective-C ABI and also implements a new ABI that is supported by
Clang and Étoilé's LanguageKit and is required for some of the newer features.

Although the runtime has been tested by several people, and is being used
extensively by the Étoilé project, it is entirely new (MIT licensed) code and
may still contain bugs.  If you come across any problems, please report them to
the GNUstep Developer mailing list <address@hidden>.  

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